Follicular fluid is the liquid bath inside each ovarian follicle, and it is far more than a passive ultrafiltrate of blood plasma. It is a dynamic biological compartment formed through selective transfer of circulating constituents across the blood-follicle barrier together with secretory products generated locally by the oocyte, cumulus cells, granulosa cells and theca cells. Its composition integrates systemic endocrine inputs with bidirectional oocyte-somatic cell communication, steroidogenesis, metabolic coupling, extracellular-matrix remodeling, periovulatory inflammation, redox homeostasis, mitochondrial function and angiogenesis. In effect, follicular fluid is a molecular record of the follicle’s physiological state, and because it is aspirated during every IVF cycle, it offers a minimally invasive window into the microenvironment that shaped each egg.

The review, led by researchers at China Medical University Hospital in Taiwan, synthesizes mechanistic and clinical evidence on follicular-fluid biomarkers associated with oocyte maturity, fertilization, embryo development, blastocyst formation, implantation and live birth. Particular attention goes to granulosa cell-associated signaling networks involving epidermal growth factor-like ligands, pentraxin 3, transforming growth factor-beta and bone morphogenetic protein family members, activins and follistatin, cytokines, steroid hormones, metabolic intermediates, lipids, oxidative-damage markers and extracellular-matrix components. Among these candidates, the steroid hormones progesterone and anti-Müllerian hormone measured in individual follicles have the most direct observational evidence, with associations reported for fertilization, embryo morphology, blastocyst development and even live birth after fresh single-embryo transfer.

Yet the review’s central conclusion is sobering: no single molecule in follicular fluid has demonstrated sufficient reproducibility, discrimination and calibration to support routine clinical prediction. The reasons are deeply rooted in follicular biology. Growth factors are pleiotropic and context-dependent, so the biological significance of one concentration cannot be interpreted independently of related ligands, receptors, binding proteins and downstream signaling activity. Functional redundancy within the transforming growth factor-beta superfamily means that alterations in one molecule may be compensated for by changes elsewhere in the network, so an apparently normal value does not necessarily indicate normal pathway activity. Follicular signaling is also temporally and spatially organized, meaning that concentrations measured at retrieval represent a time-specific composite influenced by follicle size, maturation status, ovarian stimulation, trigger regimen and the interval between triggering and aspiration.

Methodological heterogeneity compounds the problem. Patient phenotype, ovarian-stimulation regimen, follicular stage, sampling strategy, preanalytical handling, analytical platform and outcome definition all influence measured concentrations. Follicular heterogeneity and the statistical non-independence of multiple oocytes obtained from the same patient further complicate biomarker evaluation, because several follicles from one woman are biologically correlated rather than independent observations. Within-patient variability in follicular-fluid estradiol has been reported to be approximately twice the between-patient variability, underscoring how pooling fluid from multiple follicles obscures follicle-specific signals and prevents reliable linkage between a biochemical measurement and its corresponding oocyte or embryo.

The authors therefore propose a decisive transition from single-analyte measurements toward mechanism-informed, outcome-specific multianalyte panels that integrate follicular-fluid measurements with cumulus-cell or granulosa-cell transcriptomic, proteomic, metabolomic and lipidomic features. Phenotype-specific models, particularly for polycystic ovary syndrome, may further improve biological interpretation. Advanced mass-spectrometry approaches such as SWATH, a data-independent acquisition method that sequentially isolates and fragments precursor ions across predefined mass-to-charge windows, can improve analytical coverage and reproducibility for low-abundance endogenous metabolites that traditional techniques miss. A preliminary SWATH-based study identified elevated free fatty acids, 3-hydroxynonanoyl carnitine, eicosapentaenoic acid, deoxycorticosterone, phenylalanine and leucine, together with reduced lysophosphatidylcholines and phytosphingosine, in follicular fluid from women with polycystic ovary syndrome, suggesting disturbances in fatty-acid oxidation, phospholipid turnover, amino-acid metabolism and steroidogenesis.

Several biologically coherent modules emerge as promising panel foundations. Periovulatory epidermal growth factor signaling, captured by amphiregulin, reflects luteinizing hormone-induced activation of cumulus expansion and prostaglandin synthesis. Pentraxin 3, an essential structural component of the cumulus extracellular matrix, integrates stimulatory EGF-like signaling with inhibitory inputs from BMP4, BMP7, BMP6, activin A, GDF8 and TGF-beta1, making it a downstream convergence point rather than a readout of a single pathway. The activin-follistatin balance, the progesterone-to-estradiol ratio, redox markers such as glutathione and 8-hydroxy-2′-deoxyguanosine, cell-free mitochondrial DNA, acylcarnitines and lysophosphatidylcholines each represent complementary biological domains. An integrated blastocyst panel could combine metabolic function, mitochondrial or oxidative injury, and follicular-cell support in a single signature.

Clinical translation, however, demands far more than biological plausibility. The review specifies that progress will require standardized individual-follicle sampling, one-to-one linkage between biomarkers and oocyte or embryo outcomes, targeted assay development with documented accuracy, precision, linearity, recovery, stability and matrix effects, multilevel statistical modeling that accounts for follicles nested within women, independent prospective validation across different populations and laboratory platforms, and demonstration of incremental clinical utility beyond established patient and embryological variables. Mechanistic plausibility, clinical association and predictive utility must be regarded as distinct levels of evidence, because experimental changes in gene or protein expression in cultured granulosa-lutein cells do not necessarily produce corresponding changes in follicular-fluid concentrations.

The ultimate goal is a parsimonious and reproducible biomarker panel that complements, rather than replaces, conventional embryological assessment and supports more individualized IVF decision-making. Because follicular fluid is obtained only after follicular aspiration, its most plausible near-term role is research, prognostic assessment or prioritization of sibling oocytes and embryos rather than modification of the ongoing stimulation cycle. Until analytical validity, external reproducibility, clinical utility, feasibility and cost-effectiveness are demonstrated, the proposed combinations should remain investigational. Still, the vision is compelling: a small, interpretable, clinically scalable molecular readout of each follicle’s inner life, finally giving embryologists a way to see not just what an egg looks like, but what it is made of.

Subject of Research: Follicular fluid biomarkers for IVF outcome prediction

Article Title: Integrative follicular fluid biomarkers for oocyte competence and IVF outcomes: from molecular networks to multianalyte panels

Article References: Chen, C.-Y., Lu, Y.-T., Chang, P.-H., Chen, H.-J., Hsueh, Y.-W., Chang, C.-W., Hsu, H.-C., Yang, T.-C., Chang, Y.-Y., & Chang, H.-M. (2026). Integrative follicular fluid biomarkers for oocyte competence and IVF outcomes: from molecular networks to multianalyte panels. Frontiers in Endocrinology, 17, Article 1962631. https://doi.org/10.3389/fendo.2026.1962631

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1962631

Keywords: IVF, follicular fluid, biomarkers, oocyte competence, reproductive medicine, embryology, omics, Integrative, follicular, fluid, oocyte, competence

The factorial architecture is the trial’s defining technical feature. Rather than comparing a single combined treatment against a control, the investigators treat acupuncture and moxibustion as two independent randomized factors, each present or absent. Every participant receives standard oral estradiol/dydrogesterone therapy, marketed as Femoston, following a sequential 28-day regimen: one milligram of estradiol daily for the first 14 days, then one milligram of estradiol plus 10 milligrams of dydrogesterone daily for the following 14 days, providing both hormone replacement and endometrial protection. On top of this common hormonal background, women are assigned in a 1:1:1:1 ratio to Femoston alone, acupuncture plus Femoston, moxibustion plus Femoston, or combined acupuncture and moxibustion plus Femoston, with 36 participants in each group.

This design allows statisticians to estimate the main effect of acupuncture by pooling the two groups that receive it, 72 participants, against the 72 who do not, and to do the same for moxibustion. The acupuncture × moxibustion interaction, whether the two modalities amplify or interfere with one another, will also be estimated but is explicitly exploratory, because the trial was not powered specifically for that question. The investigators argue that this structure resolves an ambiguity that plagues conventional three-arm comparisons: if a combined treatment outperforms a control, it is often unclear whether the benefit arises from one component, the other, or their synergy. The factorial design disentangles those possibilities within a single trial.

The primary outcome is the change from baseline to week 12 in antral follicle count, or AFC, the total number of 2 to 9 millimeter antral follicles visible in both ovaries on transvaginal ultrasound. AFC provides a direct ultrasound-based estimate of the recruitable follicle pool and is a clinically recognized marker of ovarian reserve. The 12-week window was chosen on empirical grounds: a prior randomized study in women with POI reported measurable increases in both AFC and anti-Müllerian hormone after a comparable three-month estradiol/dydrogesterone regimen with or without adjunct acupuncture, and a recent 12-week sham-controlled trial in women with diminished ovarian reserve found that acupuncture three times weekly produced significantly greater AFC improvement than sham, although the between-group AMH difference was not statistically significant. Importantly, the protocol cautions that a biomarker change at 12 weeks should not be interpreted as restoration of the primordial follicle pool or of fertility.

Secondary outcomes span the multidimensional clinical burden of POI. Serum anti-Müllerian hormone will be measured in a central laboratory using the Roche Elecsys AMH assay on a cobas e 602 electrochemiluminescence platform, with fasting blood samples processed within two hours, centrifuged, aliquoted, stored at minus 80 degrees Celsius, and transported on dry ice from the three recruitment centers to minimize inter-laboratory variability. Follicle-stimulating hormone, luteinizing hormone, and estradiol will be measured by chemiluminescent immunoassay. Transvaginal color Doppler ultrasound will capture ovarian hemodynamic parameters, including peak systolic velocity, resistance index, and pulsatility index. Patient-reported measures include the modified Kupperman Scale for hypoestrogenic symptoms, the Self-Rating Anxiety Scale for psychological distress, Traditional Chinese Medicine syndrome scores, and menstrual status, all assessed at baseline and week 12.

Clinical pregnancy, defined as an intrauterine gestational sac with fetal cardiac activity confirmed by ultrasound, will be analyzed as an exploratory reproductive outcome recorded during treatment and at follow-up visits at weeks 24 and 48. The trial was not powered for pregnancy endpoints, and the investigators emphasize that conception during follow-up may be strongly influenced by subsequent ovulation induction, in vitro fertilization and embryo transfer, or other assisted reproductive technology. Post-randomization summaries of spontaneous conceptions versus conceptions following ART will be regarded as exploratory rather than randomized causal comparisons. Participants who become pregnant will discontinue acupuncture and moxibustion immediately and transfer to pregnancy follow-up.

The intervention protocol is standardized in unusual technical detail. The acupuncture prescription comprises two alternating treatment sets: set A, performed in the supine position, includes abdominal points CV12, CV6, CV4, bilateral ST25, ST29, EX-CA1, and leg points ST36, SP6, and LR3; set B, performed prone, includes bilateral BL23, BL32, and KI3. Needles of 0.25 by 40 millimeters and 0.30 by 75 millimeters are inserted to prespecified depths, with BL32 advanced obliquely toward the second posterior sacral foramen to 60 to 75 millimeters. Gentle lifting, thrusting, and twirling elicit Deqi, the characteristic sensation of soreness, numbness, distension, or heaviness, and needles are retained for 30 minutes. The moxibustion arm applies self-adhesive moxa column patches, each burning roughly 10 minutes, to the identical acupoints without needle insertion, three columns per session for approximately 30 minutes. In the combined group, moxibustion is applied during needle retention after Deqi is achieved. Both external therapies are delivered three times weekly for 12 weeks, totaling 36 sessions.

Because acupuncture and moxibustion are physical interventions, participants and practitioners cannot be blinded, so the trial adopts an assessor-blinded design. Recruitment and screening personnel are separated from treatment practitioners, who play no role in outcome assessment. Outcome assessors, ultrasound physicians, laboratory technicians, data-entry staff, and statisticians remain blinded to allocation throughout. To minimize measurement variability, all baseline and week-12 AFC examinations, regardless of recruitment center, will be performed centrally in the ultrasound department of the First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine using a GE HealthCare LOGIQ Fortis system with an RIC5-9-D transvaginal volume probe, and the same blinded physician will examine the same participant whenever feasible. Adverse events, including vasovagal reactions, hematomas, burns, and hormone-related symptoms such as breast tenderness and abnormal bleeding, will be recorded with a four-level severity grading scheme, and serious events reported to the ethics committee within 24 hours.

The sample size was planned from prior literature in which post-treatment AFC was 3.97 plus or minus 1.15 in the Femoston-only group and 5.14 plus or minus 1.33 in the acupuncture plus Femoston group, a between-group difference of 1.17 corresponding to Cohen’s d of approximately 0.94. G*Power calculations with 90 percent power and a two-sided alpha of 0.05 indicated 26 participants per group, increased to 36 per group to allow for roughly 20 percent dropout, for a total of 144. Within the factorial framework, each factor level includes up to 72 participants, yielding greater than 99 percent power to detect a main effect of that magnitude, with a minimum detectable standardized effect of approximately 0.54 at 90 percent power. The investigators stress that the planning benchmark derived from an acupuncture comparison does not imply the true moxibustion effect equals d of 0.94.

The trial’s eligibility criteria deliberately define a selected subgroup: women aged 22 to 40 with reproductive needs, basal FSH between 25 and 40 U/L confirmed on two occasions at least four weeks apart, and recruitment during the pretreatment phase before assisted reproduction. The investigators acknowledge that these criteria limit generalizability to adolescents, women with more advanced ovarian failure, those without fertility intentions, or patients with substantial comorbidity. The absence of sham controls means subjective outcomes such as anxiety and TCM syndrome scores may reflect treatment expectations and practitioner attention as well as specific physiological effects, although more objective biomarkers like AFC and AMH are less directly susceptible to such contextual influences. Registered with the International Traditional Medicine Clinical Trial Registry under identifier ITMCTR2025002408 and approved by the ethics committee of the First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, the trial may clarify whether either modality is associated with changes in ovarian reserve markers when added to standard hormone therapy, and may generate preliminary evidence on their potential interaction, providing a methodological basis for future larger trials designed around definitive reproductive outcomes such as live birth.

Subject of Research: Adjunctive effects of acupuncture and moxibustion in women with premature ovarian insufficiency receiving hormone replacement therapy: protocol for a multicenter, assessor-blinded, 2 × 2 factorial randomized controlled trial

Article Title: Adjunctive effects of acupuncture and moxibustion in women with premature ovarian insufficiency receiving hormone replacement therapy: protocol for a multicenter, assessor-blinded, 2 × 2 factorial randomized controlled trial

Article References: Lu, C., Ye, T., Cui, J., & Chen, B. (2026). Adjunctive effects of acupuncture and moxibustion in women with premature ovarian insufficiency receiving hormone replacement therapy: protocol for a multicenter, assessor-blinded, 2 × 2 factorial randomized controlled trial. Frontiers in Endocrinology, 17, Article 1952726. https://doi.org/10.3389/fendo.2026.1952726

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1952726

Keywords: acupuncture, moxibustion, premature ovarian insufficiency, hormone replacement therapy, factorial randomized controlled trial, reproductive medicine, Adjunctive, effects, women, premature, ovarian, insufficiency

The research team summarized outcomes from 60 uterus transplants performed between 2016 and 2025 at the four U.S. centers that have offered the procedure. Unlike smaller single-center reports, this analysis captured surgical, reproductive, neonatal, and early childhood developmental data across the full national cohort, providing an unusually complete picture of how the technique has evolved since its American debut. The results demonstrate a steep learning curve: as surgeons refined their methods and perioperative care improved, both graft survival and live birth rates climbed steadily over the ten-year window.

Senior study author Kathleen E. O’Neill, MD, MSTR, an assistant professor of Obstetrics and Gynecology at Penn and director of the Penn Uterus Transplant Program, said the data speak directly to patients weighing their options. One of the reasons she went into obstetrics, she explained, was to help give more women opportunities to start a family, and she expressed pride in the work her colleagues have done at Penn to advance the treatment. According to O’Neill, the analysis shows that uterus transplant is an effective way for women to achieve pregnancy and have children, and it should be part of the conversation alongside adoption and gestational surrogacy, giving patients and their doctors the information they need to decide whether it is the right path for them.

The medical need is substantial. Absolute uterine factor infertility—the absence of a uterus either from birth or following hysterectomy—affects roughly 3 percent of women. Most transplant recipients in the study had Mayer-Rokitansky-Küster-Hauser syndrome, a congenital condition in which the uterus does not develop, while others had undergone hysterectomy or carried a uterus unable to support pregnancy. Before transplantation became viable, these patients had no biological path to carrying a child; their only routes to parenthood were adoption or gestational surrogacy, both of which carry legal, financial, and emotional complexities of their own.

Penn Medicine has played a central role in the field’s development. Under O’Neill’s leadership, Penn’s first birth from a uterus transplant occurred in November 2019 with the arrival of baby Benjamin Gobrecht, whose mother had been born without a uterus and received her new organ from a deceased donor through the Gift of Life program as part of Penn’s UNTIL uterus transplant trial. Since that landmark delivery, Penn has recorded eight babies born from seven transplants, most of them sourced from living donors. Notably, three of those transplant recipients, all of whom have already delivered a healthy baby, are now trying to become pregnant again, a testament to the durability of the transplanted organs and the possibility of repeated successful pregnancies.

The quantitative gains documented in the review are striking. Researchers found that 51 of the 60 transplanted uteruses survived beyond the critical first 30 days after surgery, the period during which vascular complications and immune rejection most often claim the graft. Among the women who received those surviving organs, more than 82 percent ultimately achieved at least one live birth or were still pregnant at 20 weeks or later when the study closed. Even more telling is the trajectory of surgical failure: since 2020, only one graft failure has occurred among 31 transplants performed nationwide, reflecting major improvements in surgical technique, donor selection, and postoperative management that have transformed the procedure’s risk profile.

Cumulatively, 48 babies were born to uterus transplant recipients in the United States across the study period. Nine recipients delivered two children each, demonstrating that a single transplanted uterus can support multiple full pregnancies before the organ is removed. This pattern matters clinically because the procedure is intentionally temporary: recipients typically keep the graft only long enough to complete their family, after which the uterus is removed to allow discontinuation of immunosuppressive drugs. The ability to achieve repeated pregnancies within that window multiplies the value of each transplant and reduces the total immunological burden on the patient.

Donor safety has improved in parallel with recipient outcomes. Among living donors, major complications requiring additional intervention declined from 33 percent in 2016 and 2017 to just 8 percent in 2024 and 2025, a dramatic reduction over the study period. Across the entire cohort, no recipient and no living donor experienced a life-threatening complication or death related to the procedure. These figures address one of the most serious ethical concerns surrounding uterus transplantation from the outset, namely the exposure of healthy donors to major abdominal surgery for the benefit of another person, and they strengthen the case for expanding the practice under carefully monitored protocols.

Reproductive success, however, has not eliminated the obstetric challenges inherent to pregnancy with a transplanted organ. More than half of the babies, 58 percent, were born prematurely, and complications such as preeclampsia, gestational diabetes, and hypertension were relatively common among recipients. Researchers also tracked the health and development of the children born after transplantation. All children demonstrated normal development at hospital discharge and at six months of age. Among 29 children evaluated at age 3, investigators observed normal growth and no cases of failure to thrive. Two children had been diagnosed with autism spectrum disorder, while no other developmental disorders were identified. O’Neill said both recipients and babies will continue to be followed, and research is underway to better understand why the pregnancy complications are occurring, work that could eventually inform strategies to reduce preterm birth and hypertensive disorders in this population.

Despite the encouraging outcomes, the authors identified access as the field’s greatest remaining barrier. Uterus transplantation is available at only a handful of centers nationwide, including Penn, and it is generally not covered by insurance, leaving the treatment financially out of reach for many eligible patients. O’Neill expressed hope that the analysis will show insurance companies, and those who can invest in making the procedure more widely available, that there is now a technique allowing more women to become mothers, adding that women deserve access and options when it comes to how to start a family. As the decade of data continues to accumulate, uterus transplantation stands poised to move from a pioneering handful of programs toward a recognized standard of care for absolute uterine factor infertility, provided that the systems of coverage and referral catch up with the science.

Subject of Research: Outcomes of uterus transplantation for absolute uterine factor infertility in the United States

Article Title: New analysis shows that uterus transplants help women achieve successful pregnancies

Article References: New analysis shows that uterus transplants help women achieve successful pregnancies. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: uterus transplant, uterine factor infertility, MRKH syndrome, Penn Medicine, live birth outcomes, organ transplantation, preterm birth, living donors, immunosuppression, reproductive medicine, preeclampsia, Obstetrics and Gynecology

The study, published in the Journal of Ovarian Research, comes from the Institute for Maternal and Child Health IRCCS Burlo Garofolo and the University of Trieste. First author Alessandro Biscontin and colleagues tackled a problem that has long frustrated embryologists: morphology-based assessment of metaphase II oocytes, the mature eggs used in intracytoplasmic sperm injection, is a cornerstone of ICSI workflows but suffers from inter-operator variability and limited reproducibility. Two experts looking at the same microscopic image can disagree on where one structure ends and another begins, and purely data-driven deep learning models inherit a different version of the same problem, generating anatomically implausible segmentations when the training data does not cover every visual contingency.

The researchers’ answer is a neurosymbolic architecture, a design philosophy that pairs the pattern-recognition power of neural networks with the explicit, human-readable constraints of symbolic artificial intelligence. In their system, a transformer-based segmentation model called SegFormer first predicts regions of interest in a microscopic image of a denuded MII oocyte. A logic score, derived from a set of knowledge-driven anatomical constraints, is then computed on those predicted regions. The constraints encode structural facts that embryologists know by heart: the zona pellucida forms a coherent ring around the cell, the perivitelline space lies between the oolemma and the zona pellucida, the first polar body sits within or adjacent to that space, and the cytoplasm occupies the interior. When the network’s predictions violate these relationships, the logic score drops.

What makes the approach technically elegant is how the logic score is used. During training, it functions as an auxiliary loss, computed alongside the standard segmentation loss, so that parameter updates are guided not only by pixel-level agreement with ground-truth annotations but also by whether the emerging segmentation is morphologically coherent. At inference time, the same score becomes a continuous measure of morphological reliability, a number that tells the user how anatomically plausible the model’s output is for a given image. The framework is model-agnostic in spirit: the authors also applied the logic loss to a convolutional backbone, showing that the benefit is not tied to the transformer architecture alone.

The dataset behind the study is substantial. The team retrospectively analyzed 1,243 microscopic images acquired at 200× magnification from 218 patients undergoing ICSI at a single reproductive medicine center. Written informed consent was obtained from all participants, and the study received ethical approval from the institutional review board under protocol IRB-BURLO 05/2022. Each image was annotated for the structures that matter in oocyte assessment: the zona pellucida, the perivitelline space, the first polar body, the cytoplasm, and the background, along with the holding and injection pipettes visible in the ICSI setup.

The quantitative results are striking. The neurosymbolic model achieved a macro-average intersection over union of 0.84 and a Dice similarity score of 0.91, outperforming an architecturally identical SegFormer baseline that reached an IoU of 0.80 and a Dice of 0.88. Classic convolutional architectures trained on the same dataset and split fared worse still: U-Net reached an IoU of 0.76, while DeepLabV3+ managed 0.81. In semantic segmentation, where IoU measures the overlap between predicted and true regions for each anatomical class, a four-point gain over an identical baseline is a meaningful improvement, and the gain came without any change to the network architecture or the amount of training data.

Perhaps the most important part of the study is the set of controls the authors designed to prove that the improvement comes from the content of the logical rules rather than from the mere presence of an auxiliary term. They trained two controls with identical loss form and weight but no anatomical meaning: a non-structural auxiliary loss and a scrambled rule set. The non-structural auxiliary loss of equal weight did not reproduce the gain, reaching an IoU of 0.81 and a Dice of 0.88, essentially matching the baseline. Scrambling the semantics of the rules degraded performance dramatically, dropping the IoU to 0.61. The message is unambiguous: the improvement is driven by what the constraints say, not by how they are mathematically packaged.

This control design addresses a subtle criticism that has dogged auxiliary-loss approaches in machine learning. It is easy to add a term to a loss function and observe a performance bump, but harder to demonstrate that the bump reflects genuine knowledge rather than a generic regularization effect. By showing that a meaningless auxiliary term of the same weight produces no benefit, and that scrambling the rules actively harms performance, the authors provide evidence that domain knowledge, when formalized as logical constraints, is a real and transferable ingredient of model training. The scrambled-rule result also hints at the framework’s sensitivity: constraints that contradict anatomy do not merely fail to help, they mislead the network.

The implications reach beyond oocyte imaging. Assisted reproductive technologies are increasingly supported by automated image analysis, from sperm selection to embryo grading, and the field faces the same twin challenges everywhere: deep learning models are powerful but opaque, and their predictions can fail in ways that clinicians cannot easily anticipate. A neurosymbolic layer offers a partial remedy. Because the constraints are explicit and human-readable, an embryologist can inspect them, verify that they match clinical understanding, and even modify them as knowledge evolves. Because the logic score is computed at inference time, it can serve as a continuous quality indicator, flagging predictions that are statistically plausible but anatomically suspect before they reach a decision-support workflow.

The authors are careful to position the framework as an image-analysis component for future decision-support systems in ICSI workflows rather than as a standalone clinical tool. The study was retrospective, single-center, and focused on denuded MII oocytes at a fixed magnification, so external validation across centers, magnifications, and imaging setups remains future work. Still, the demonstration that anatomical knowledge can be embedded as logical constraints and measurably improve both accuracy and morphological coherence marks a promising direction for artificial intelligence in reproductive medicine. As the authors conclude, embedding domain knowledge as logical constraints yields more accurate and morphologically coherent segmentations of MII oocyte images than a purely neural baseline, and that hybrid recipe, logic guiding learning, may prove just as valuable wherever medical image analysis meets clinical anatomy.

Subject of Research: Neurosymbolic deep learning with anatomical logical constraints for semantic segmentation of metaphase II human oocyte microscopy images

Article Title: Neurosymbolic approach improves robustness of deep learning models for semantic segmentation of MII human oocyte images

Article References: Biscontin, A., Ajčević, M., Luppi, S., Giolo, E., Miladinović, A., Bottega, R., De Rocco, D., Martinelli, M., Accardo, A., Skerk, K., Zito, G., & Ricci, G. (2026). Neurosymbolic approach improves robustness of deep learning models for semantic segmentation of MII human oocyte images. Journal of Ovarian Research. https://doi.org/10.1186/s13048-026-02286-5

Image Credits: AI Generated

DOI: 10.1186/s13048-026-02286-5

Keywords: neurosymbolic AI, deep learning, semantic segmentation, oocyte, ICSI, zona pellucida, transformer, medical image analysis, reproductive medicine, Journal of Ovarian Research, Neurosymbolic, approach

The research team built their framework around two public datasets. The first was a global fertility rate time series spanning 1960 to 2020, drawn from Kaggle, which captures decades of demographic change across countries. The second was an electronic health record-derived male fertility dataset containing 100 participants and 10 features, originally sourced from the UCI Machine Learning Repository. Each participant’s sperm concentration had been assessed against World Health Organization 2010 standards, and the features ranged from age and season of assessment to childhood diseases, surgical history, alcohol consumption frequency, smoking habits, and daily sitting duration. The diagnosis column, classifying each man as having normal or altered fertility, served as the prediction target.

Before any modeling began, the researchers put both datasets through a rigorous preprocessing pipeline. Missing years were removed from countries with incomplete temporal sequences in the fertility rate data, and values were normalized using Min-Max scaling before being converted into fixed-length sliding windows of ten years. For the male fertility dataset, categorical variables such as season and alcohol frequency were one-hot encoded, binary variables were label encoded, and numerical features like age and sitting hours were standardized. The team also checked for multicollinearity using Pearson’s correlation, retaining only features below a threshold of 0.85, and addressed class imbalance through random undersampling to preserve generalizability.

With the data prepared, the researchers deployed an unusually broad arsenal of Long Short-Term Memory (LSTM) architectures. LSTMs are a type of recurrent neural network designed to model sequential data while sidestepping the vanishing gradient problem through memory cells and gating mechanisms. The team tested unilateral LSTMs, which process sequences in a single forward direction; bidirectional LSTMs, which read data from both past and future contexts; hierarchical and attention-based LSTMs, which layer recurrent processing and dynamically weight the most informative time steps; convolutional LSTMs, which replace fully connected operations with convolutions inside the gating mechanism; LSTM autoencoders, which compress and reconstruct sequences; grid LSTMs, which extend recurrence across multiple dimensions; and cross-modal and associative LSTMs, which integrate information from multiple data types. Each variant was configured with 64 hidden units, tanh activation, sigmoid gates, a dropout rate of 0.2, the Adam optimizer, a learning rate of 0.001, and a batch size of 32, trained for 20 epochs with early stopping.

The centerpiece of the study, however, was a novel Quantum LSTM that embeds a Variational Quantum Circuit (VQC) directly within the LSTM’s input gating mechanism rather than using it as a postprocessing feature extractor, as most prior hybrid quantum-classical models have done. The quantum component used eight qubits with angle encoding via RX and RY rotations, two variational layers with CNOT entanglement gates, and a circuit depth of 18 gates per forward pass, yielding 64 trainable quantum parameters. The circuit replaced the input-to-hidden weight matrix in the LSTM’s input gate only, leaving the forget, output, and cell gates entirely classical. This architectural choice allows quantum superposition and entanglement to directly influence temporal memory updates, a distinction the authors argue sets their approach apart from earlier designs that treat quantum circuits as bolt-on feature enhancers.

To establish a fair baseline, the team also ran four conventional machine learning algorithms on both datasets: logistic regression, random forest, support vector machine, and XGBoost. XGBoost emerged as the strongest classical baseline, achieving 89.4 percent accuracy on the fertility rate data and 89.7 percent on the male fertility data, with random forest close behind at 88.3 and 89.2 percent respectively. These results confirmed that ensemble-based methods remain formidable competitors on small, structured datasets, but they also underscored the value of LSTM architectures for capturing sequential and temporal patterns that tree-based models cannot easily represent.

Among the classical LSTM variants, the unilateral LSTM proved the most consistent performer, reaching 91.2 percent accuracy on the fertility rate dataset in 79 seconds and 92.1 percent on the male fertility dataset in 82 seconds. The Quantum LSTM outperformed all classical models on both datasets, achieving 92.6 percent accuracy on the fertility rate data with a training time of 74 seconds and 93.8 percent on the male fertility data in 79 seconds. The absolute improvement over the best classical baseline was modest, roughly one to two percentage points, but the team validated it through three independent strategies: fivefold cross-validation to reduce bias, ten repeated random train-test splits to measure variance and stability, and 1,000 iterations of bootstrap resampling to quantify uncertainty through confidence intervals.

Statistical testing confirmed that the Quantum LSTM’s advantage was real rather than an artifact of sampling noise. The Friedman non-parametric test, applied across repeated validation runs, revealed significant differences among the LSTM architectures on both datasets, with P-values of 0.0009 for the fertility rate data and 0.0012 for the male fertility data. Pairwise Wilcoxon signed-rank tests comparing the Quantum LSTM against the unilateral LSTM across fivefold cross-validation yielded P-values of 0.031 and 0.024, both below the conventional 0.05 threshold, with small to moderate effect sizes (Cohen’s d of 0.42 and 0.48). The Quantum LSTM also exhibited narrower bootstrap confidence intervals and lower standard deviations than its classical counterpart, suggesting greater stability under repeated resampling even with limited data.

To make the model’s decisions transparent, the researchers applied SHAP (SHapley Additive exPlanations), an interpretability framework rooted in cooperative game theory that assigns each feature an importance value based on its marginal contribution to predictions. On the male fertility dataset, daily sitting duration emerged as the single most influential predictor, with a mean absolute SHAP value of approximately 0.22, followed closely by age at roughly 0.18. Season of assessment and frequency of alcohol consumption ranked third and fourth with importance scores of about 0.13 and 0.12 respectively. Clinical history variables, including smoking habits, childhood diseases, accidents or serious trauma, high fevers in the last year, and surgical intervention, contributed comparatively less, with SHAP values ranging from approximately 0.07 to 0.08. On the fertility rate dataset, SHAP analysis revealed that the most recent years, particularly 2019, carried the greatest predictive weight, while observations from earlier decades such as 1985 and 2001 contributed far less, indicating that the model relies on both short-term and long-term temporal dependencies.

The authors are careful to frame their findings as hypothesis-generating rather than clinically conclusive. The male fertility dataset contained only 100 participants from a single source, the quantum circuit was executed on a simulator rather than real quantum hardware, and all observed associations between fertility outcomes and lifestyle or clinical variables are correlational, not causal. The study also lacked genetic, hormonal, imaging, and longitudinal data, and the models are not intended for direct clinical deployment. Nevertheless, the work establishes a reproducible benchmarking framework that combines classical LSTM variants, a quantum-enhanced LSTM, and SHAP-based explainability for exploratory male infertility risk stratification. The researchers call for future validation on larger, multi-center electronic health record cohorts and on real quantum hardware, where gate noise, decoherence, and qubit connectivity constraints will test whether the modest gains observed in simulation translate into meaningful clinical advantage.

Subject of Research: A hybrid quantum-classical deep learning framework for interpretable male infertility risk prediction using electronic health record data

Article Title: A data-driven and interpretable hybrid quantum-classical model for male infertility risk assessment

Article References: Sarath, T., & Brindha, K. (2026). A data-driven and interpretable hybrid quantum-classical model for male infertility risk assessment. Frontiers in Medical Technology, 8, Article 1853728. https://doi.org/10.3389/fmedt.2026.1853728

Image Credits: AI Generated

DOI: 10.3389/fmedt.2026.1853728

Keywords: male infertility, quantum machine learning, LSTM, variational quantum circuit, electronic health records, SHAP, deep learning, fertility prediction, quantum computing, risk assessment, healthcare AI, reproductive medicine

CAH is a group of autosomal recessive disorders caused by defects in the enzymes that manufacture cortisol in the adrenal glands. In roughly 90 percent of cases, the culprit is a mutation in the gene encoding 21-hydroxylase. When cortisol production falls short, the pituitary gland responds by pumping out adrenocorticotropic hormone, or ACTH, which chronically stimulates the adrenals and drives them to overproduce androgens. The severity of the resulting disease depends on how much residual enzyme activity remains. The classic salt-wasting form typically announces itself in the newborn period, the simple virilizing form preserves partial cortisol production, and the milder non-classic form often goes undetected until adolescence or adulthood, sometimes only surfacing during an infertility work-up. Diagnosis hinges on measuring 17-hydroxyprogesterone, the steroid precursor that accumulates when 21-hydroxylase is deficient, with newborn screening now enabling early detection of classic disease.

For girls and women with classic CAH, the endocrine obstacles to reproduction are formidable. Adrenal androgen excess disrupts follicular maturation and ovulation, while elevated 17-hydroxyprogesterone acts much like a contraceptive progestin: it binds the progesterone receptor or is converted to progesterone itself, thickening cervical mucus, impairing endometrial development and suppressing ovulation. Elevated androgens and progesterone can also disturb the pulsatile secretion of luteinizing hormone, further scrambling menstrual cycles. The clinical data are sobering. In a Swedish population-based cohort of 272 women with CAH, only 25.4 percent had at least one child, and affected women had fewer children and were older at the birth of their first child than controls. Menstrual disturbances occur in more than 30 percent of women with classic CAH who are not using hormonal contraception, and more severe genotypes are consistently associated with poorer reproductive outcomes.

Yet the picture is far from hopeless, and the review emphasizes that biology is only part of the story. Adequate glucocorticoid replacement can restore hormonal balance, and in well-controlled patients fecundity can approach that of the general population. In a multicenter study of 72 adult women with different CAH phenotypes, time to pregnancy was often prolonged, with a median ranging from 8 to 24 months, and about a quarter of the women required fertility-enhancing medication or assisted reproductive techniques. Despite that, live birth numbers per woman and miscarriage rates were broadly comparable to the general population. Intriguingly, lower birth rates in women with classic CAH may partly reflect a reduced desire for parenthood rather than absolute infertility: only 23.6 percent of women with classic disease in one study expressed a wish for pregnancy, compared with nearly half of women with non-classic CAH, a gap that points squarely at psychosocial influences.

Those psychosocial influences run deep. Psychosexual development in girls with classic CAH is shaped by prenatal androgen exposure, chronic endocrine imbalance, genital reconstructive surgery and body image concerns, factors that accumulate from early childhood onward. Females with CAH report higher rates of sexual dysfunction than controls, including vaginal stenosis, reduced lubrication, diminished genital sensitivity and painful intercourse, and in one cohort more than one-third of women with CAH had never engaged in vaginal intercourse at all. Repeated surgical procedures in childhood and adolescence carry significant psychological burden, and women with null mutations report lower sexual satisfaction and more surgical complications. Gender identity presents additional complexity: reviews suggest roughly 94.8 percent of 46,XX individuals raised as girls maintain a female gender identity, with about 4 to 5 percent experiencing gender identity difficulties, rates that rise substantially in those raised as males. Factors associated with later gender dysphoria include marked virilization, delayed diagnosis and poor hormonal control, underscoring the need for repeated, developmentally appropriate psychological assessment.

Non-classic CAH tells a subtler story in girls. Because the enzyme defect is milder, most affected girls have normal external genitalia and become symptomatic only in late childhood or adolescence, when hyperandrogenic features emerge. Premature pubarche is often the first sign, with one study finding that 92 percent of girls under ten presented this way. During adolescence, hirsutism, acne, alopecia and menstrual disturbances become prominent: in a cohort of 220 adolescents, 56 percent had irregular menses and 9 percent had primary amenorrhea. The phenotype closely resembles polycystic ovary syndrome, including polycystic ovarian morphology. Fertility is generally less affected than in classic disease and most women conceive spontaneously, but reduced fertility is still reported in 10 to 30 percent of women of reproductive age, primarily through anovulation. The stakes of early diagnosis are vivid: live birth rates were 86 percent in women diagnosed before conception versus 69 percent in those diagnosed only after pregnancy, and miscarriage rates fell from about 25 percent before diagnosis to roughly 10 percent after treatment began.

For males with classic CAH, the reproductive threats are different but equally serious. Hypogonadotropic hypogonadism, in which adrenal-derived steroids suppress the hypothalamic-pituitary-gonadal axis through negative feedback, is observed in 20 to 52 percent of men with 21-hydroxylase deficiency, and impaired semen quality or reduced sperm concentrations have been described in up to two-thirds of affected individuals. Multiple steroids contribute to this suppression, including testosterone acting through the androgen receptor, androstenedione after aromatization to estradiol, and 17-hydroxyprogesterone and progesterone through the progesterone receptor. Recently, 11-oxygenated adrenal androgens such as 11-ketotestosterone have emerged as potent contributors whose androgenic activity rivals that of classical androgens, potentially explaining why some men with low circulating testosterone show few obvious symptoms of deficiency. Because adrenal and testicular testosterone are biologically indistinguishable, clinicians can use the androstenedione-to-testosterone ratio, with values of 0.5 or higher suggesting significant adrenal contribution, to identify the source of hormonal disruption.

The most distinctive threat to male fertility, however, is the testicular adrenal rest tumor, or TART, a benign lesion that histologically resembles adrenocortical tissue and typically originates in the rete testis. Prevalence is estimated at 30 to 50 percent in adolescent boys and adult men with classic CAH, with bilateral occurrence in about 80 percent of cases. Tumors smaller than two centimeters cannot be detected by palpation, making scrotal ultrasound the diagnostic modality of choice, while magnetic resonance imaging offers no meaningful advantage. Current evidence suggests TARTs may arise not from embryonic adrenal rests, as long assumed, but from pluripotent steroidogenic cells, possibly fetal Leydig cell precursors, whose proliferation is driven by chronic ACTH excess and, during puberty, possibly by luteinizing hormone. Larger tumors can mechanically obstruct seminiferous tubules, damage Sertoli cells and germ cells, and produce azoospermia, and because they retain adrenal-like enzymatic machinery they can locally manufacture androgens, including 11-oxygenated varieties, that may further impair spermatogenesis through paracrine effects. Encouragingly, biochemical hypogonadism appears to be a stronger determinant of impaired spermatogenesis than tumor bulk alone, and intensifying glucocorticoid therapy to suppress ACTH can shrink tumors and sometimes restore fertility, an approach that works best in younger patients before fibrosis sets in.

The review’s practical recommendations follow from these findings. Boys with classic CAH should begin annual scrotal ultrasound screening for TARTs around age eight, and sperm cryopreservation should be offered when tumors are detected even if paternity is not yet desired. Preliminary evidence suggests a modified-release hydrocortisone formulation can improve sperm quality and gonadal function without increasing overall glucocorticoid exposure, while testis-sparing surgery has not been shown to improve fertility and should be reserved for pain. For women planning pregnancy, endocrine optimization is the cornerstone: hydrocortisone is preferred for its short half-life, adequate mineralocorticoid replacement may improve fertility even without overt salt wasting, and dexamethasone should be avoided during pregnancy because it crosses the placenta. Genetic counseling should be offered to all patients, beginning in adolescence, since classic 21OHD occurs in roughly 1 in 10,000 to 15,000 newborns and the carrier frequency is estimated at about 1 in 55 in the general population. Prenatal dexamethasone treatment, which must begin before gestational week eight to prevent virilization of affected female fetuses, remains controversial and is limited to specialized centers and research settings given unnecessary fetal exposure and uncertain long-term effects. Above all, the authors insist, structured transition care, beginning in early adolescence and tailored to readiness rather than age, with counseling on sexuality, fertility, contraception, inheritance and pregnancy planning delivered by multidisciplinary teams, is the single most powerful tool for converting these reproductive risks into manageable, and often reversible, challenges.

Subject of Research: Reproductive and fertility challenges in adolescents with congenital adrenal hyperplasia

Article Title: Reproductive and fertility challenges in adolescents with congenital adrenal hyperplasia

Article References: Tschaidse, L., Auer, M. K., Nowotny, H. F., & Reisch, N. (2026). Reproductive and fertility challenges in adolescents with congenital adrenal hyperplasia. Frontiers in Adolescent Medicine, 4, Article 1878713. https://doi.org/10.3389/fradm.2026.1878713

Image Credits: AI Generated

DOI: 10.3389/fradm.2026.1878713

Keywords: congenital adrenal hyperplasia, fertility, adolescence, 21-hydroxylase deficiency, testicular adrenal rest tumors, hyperandrogenism, psychosexual development, genetic counseling, transition care, endocrinology, pregnancy, reproductive medicine

The research team, led by Shasha Liu and Fuping Li of the hospital’s Human Sperm Bank together with colleagues in pediatric hematology-oncology nursing, surveyed parents of boys aged zero to twelve years who were being treated for cancer. The study followed the STROBE guidelines for cross-sectional research and divided participants into two distinct groups: those whose sons had not yet started cancer treatment and those whose sons had already undergone therapy. This pre- and post-treatment stratification is more than a methodological nicety. It captures two fundamentally different decision windows. Before treatment, parents face an urgent, often overwhelming choice with a hard deadline, because many fertility preservation options must be pursued before gonadotoxic therapy starts. After treatment, the window has largely closed, and the decision landscape changes entirely.

In total, 134 patients were enrolled, with a mean age of just 6.0 years and a standard deviation of 2.9—meaning most of the boys were far too young to make or even understand reproductive decisions themselves. The responsibility fell entirely on their parents. When asked, 64.9 percent of parents—87 of the 134—expressed willingness to pursue fertility preservation for their sons. That roughly two-thirds figure is notable in itself, but the study’s real analytical power comes from its multivariable logistic regression models, which were run separately for each treatment group to identify which factors independently predicted parental willingness.

The results split cleanly along the treatment timeline. Among parents whose sons had not yet begun cancer therapy, the single significant predictor was a democratic parenting style. Parents who reported involving their children in decisions, listening to their views, and sharing authority were more than three and a half times as likely to be willing to pursue fertility preservation, with an odds ratio of 3.557 and a 95 percent confidence interval running from 1.094 to 11.567. The authors suggest that this parenting orientation reflects a broader openness to considering the child’s future personhood—including his eventual capacity to have his own family—even when that future cannot be discussed with the child directly.

In the post-treatment group, the picture changed. Here, two factors emerged as significant. The first was parental education: parents with higher educational attainment were roughly four times as willing to pursue fertility preservation (odds ratio 4.054, 95 percent confidence interval 1.021 to 16.094). The second was health belief: for each unit increase in parents’ scores on the health belief measures used in the study, willingness rose by 17 percent (odds ratio 1.170, 95 percent confidence interval 1.045 to 1.309). In other words, once treatment was underway or complete, what mattered was no longer how parents parented, but how much they knew and how strongly they believed that cancer treatment threatens fertility and that preservation offers a genuine benefit.

That second finding aligns with the Health Belief Model, the theoretical framework the researchers used to structure their inquiry. Developed in the 1950s to explain why people fail to use preventive health services, the model proposes that health behavior depends on perceived susceptibility to a threat, perceived severity of its consequences, perceived benefits of taking action, perceived barriers to doing so, and internal cues that prompt action. Applied to fertility preservation, the model predicts that a parent who understands that gonadotoxic therapy can cause infertility, who views that infertility as a serious harm to their child’s future quality of life, and who believes preservation is effective and feasible, will be far more likely to act. The post-treatment data bear this out: parents who had lived through the treatment experience, and who had absorbed its implications for reproduction, showed willingness that tracked closely with the strength of those beliefs.

The biology underlying the whole enterprise deserves attention. The germ cells in prepubertal testes—spermatogonial stem cells—are exquisitely vulnerable to alkylating chemotherapy agents and to radiation, both of which deplete the stem cell pool that would otherwise drive spermatogenesis after puberty. For adolescent boys who have already begun producing sperm, the standard of care is straightforward: semen cryopreservation before treatment. For prepubertal boys, however, there is no sperm to freeze, and the field relies on experimental approaches, most notably testicular tissue cryopreservation, in which a small biopsy containing spermatogonial stem cells is frozen with the hope of future reimplantation or in vitro maturation. These techniques remain investigational, but the stakes are high, and the decision to bank tissue must be made in the narrow interval between diagnosis and the first chemotherapy cycle—a window that can be measured in days.

This is why the study’s central conclusion is so pointed: parents’ recognition of cancer treatment’s impact on fertility, and their understanding of what fertility preservation can actually offer, are the key drivers of decision-making. Before treatment, when families are reeling from a new cancer diagnosis, those understandings are often incomplete, and the decision may hinge on temperament and family dynamics—hence the prominence of democratic parenting in the pre-treatment model. After treatment, when the emotional fog has partially lifted and parents have had time to learn, knowledge and belief take over. The asymmetry between the two models is itself the finding: the pre-treatment window, the one that matters most biologically, is the one in which parents are least equipped cognitively to make an informed reproductive choice.

The clinical implications follow directly. The authors argue that healthcare providers should initiate timely, clear communication about fertility preservation options before treatment begins, not after. This means that oncologists, nurses, and reproductive medicine specialists need protocols that bring fertility counseling into the earliest moments of pediatric cancer care, alongside consent discussions for chemotherapy itself. In China, where sperm banks exist in major cities but pediatric fertility preservation services remain unevenly distributed, the logistics are formidable. Testicular tissue cryopreservation is available at only a handful of centers, and many families live far from any facility equipped to perform and store such biopsies. Distance, cost, and the simple scarcity of counseling time during a medical crisis all act as barriers that the Health Belief Model would predict will suppress uptake.

At the policy level, the study’s recommendations are equally concrete: integrate fertility preservation counseling into standard oncology care and provide accessible educational resources for parents. In practice, that could mean decision aids in local languages, standardized counseling scripts for pediatric oncology teams, and formal referral pathways from oncology units to reproductive medicine services. The study was supported by the Sichuan Science and Technology Program, and its authors span the sperm bank, pediatric nursing, and pediatrics departments of the same hospital—an institutional arrangement that itself models the kind of collaboration the recommendations require. For the roughly two-thirds of Chinese parents who already say yes to fertility preservation, and for the third who hesitate, the message from Chengdu is clear: the conversation about a child’s future family should start on the day of diagnosis, not when the treatment is over and the options have narrowed to memory.

Subject of Research: Parental decision-making about fertility preservation for male children and adolescents undergoing cancer treatment in China

Article Title: Fertility preservation in young male adolescents and children before and after treatment with cancer in China: factors influencing the decision of parents

Article References: Liu, S., Ma, J., Yuan, J., Zhou, J., Luo, B., Lu, X., & Li, F. (2026). Fertility preservation in young male adolescents and children before and after treatment with cancer in China: factors influencing the decision of parents. BMC Cancer. https://doi.org/10.1186/s12885-026-17108-6

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17108-6

Keywords: fertility preservation, pediatric oncology, parental decision-making, China, spermatogonial stem cells, testicular tissue cryopreservation, Health Belief Model, chemotherapy-induced infertility, hematologic malignancies, health communication, reproductive medicine, childhood cancer survivors

Follitropin delta is a recombinant follicle-stimulating hormone, or FSH, produced in a human cell line, which gives it higher biopotency than earlier recombinant products derived from hamster cells. Because of this increased potency, the drug is measured in micrograms rather than the international units used for other gonadotrophins. When regulators approved it, they endorsed an individualised dosing algorithm that takes a patient’s anti-Müllerian hormone level and body weight into account. That algorithm, however, was validated in gonadotrophin-releasing hormone antagonist protocols culminating in fresh embryo transfer. In freeze-all cycles, where ovarian stimulation is deliberately decoupled from embryo transfer to reduce the risk of ovarian hyperstimulation syndrome and to allow endometrial preparation on the patient’s own timetable, the algorithm’s assumptions no longer hold neatly, and many clinics have found it cumbersome to apply.

The progestin protocol has emerged as an increasingly adopted alternative for freeze-all IVF cycles. Instead of using a GnRH agonist or antagonist to prevent the premature surge of luteinising hormone that could trigger ovulation before egg retrieval, clinicians administer a progestin, a synthetic progesterone-like compound, which suppresses the surge effectively and inexpensively. Combined with the freeze-all strategy, in which all embryos are cryopreserved and transferred in a later, physiologically calmer cycle, the progestin protocol has expanded access to IVF in many settings. Yet no evidence existed on how follitropin delta’s simplified dosing regimens, which had shown promise in antagonist protocols, would perform in this context. The new study set out to fill that gap.

Researchers led by Tien Khac Le of IVFMD Phu Nhuan, My Duc Phu Nhuan Hospital, and colleagues across several Vietnamese institutions conducted a multicentre retrospective cohort study spanning May 2023 to September 2024 at three tertiary hospitals: My Duc Hospital and My Duc Phu Nhuan Hospital in Ho Chi Minh City, and the Family Hospital in Da Nang. They included women undergoing their first IVF or intracytoplasmic sperm injection cycle with a progestin protocol and a freeze-all indication. Patients received either follitropin delta at one of three fixed starting doses of 9, 12, or 18 micrograms per day, or follitropin alfa at 150, 225, or 300 international units per day, with the dose in both groups selected according to the woman’s anti-Müllerian hormone level. This stratified, fixed-dose approach deliberately bypasses the complex individualised algorithm, trading mathematical precision for bedside simplicity.

Because the study was observational rather than randomised, the investigators faced the familiar challenge of confounding: women prescribed one drug might differ systematically from those prescribed the other in age, weight, or ovarian reserve. To address this, they used propensity score matching, a statistical technique that pairs patients from the two treatment groups who share similar baseline characteristics. Matching was performed on age, body mass index, anti-Müllerian hormone, and antral follicle count, the ultrasound-based measure of resting follicles. After matching, 342 women per group were analysed for stimulation and laboratory outcomes, and 315 women in the follitropin alfa group and 314 in the follitropin delta group completed the analysis of their first frozen embryo transfer. The primary outcome was live birth following that first frozen transfer.

The headline result was reassuring equivalence. The live birth rate after the first frozen embryo transfer was 40.1 percent in the follitropin delta group compared with 41.6 percent in the follitropin alfa group, a difference captured by a relative risk of 0.97 with a 95 percent confidence interval of 0.8 to 1.2 and a p value of 0.8. In plain terms, the two regimens produced essentially indistinguishable chances of a baby from the first transfer, and the statistical interval comfortably spans the possibility of no difference at all. For a drug whose potency and dosing logic differ fundamentally from the long-standing standard, that finding carries considerable clinical weight.

Where the regimens diverged was in efficiency. Women receiving follitropin delta completed ovarian stimulation in a median of eight days, compared with nine days in the follitropin alfa group, a difference that was highly statistically significant. Crucially, the shorter stimulation did not come at the cost of follicular yield: the number of follicles measuring at least 14 millimetres and the number of oocytes retrieved were similar between the groups. The authors report that other embryological outcomes, pregnancy outcomes, and neonatal outcomes were also comparable, suggesting that the more potent hormone compressed the stimulation timeline without degrading the quality of the eggs, embryos, or eventual pregnancies that resulted.

Safety findings were equally notable. Not a single case of ovarian hyperstimulation syndrome occurred in either arm of the matched cohort, an outcome that reflects both the freeze-all strategy itself, which removes the pregnancy-driven amplification of the syndrome, and careful dose stratification by ovarian reserve. Ovarian hyperstimulation syndrome remains one of the most feared complications of IVF, and any regimen that maintains live birth rates while keeping that risk at zero in a large cohort will attract attention from clinicians seeking safer stimulation protocols, particularly in settings where high-responder populations are common.

The study’s design does impose limits on how far the conclusions can travel. As a retrospective propensity-matched cohort, it cannot eliminate residual confounding the way a randomised trial would, and the fixed-dose stratification was applied according to local clinical practice rather than a pre-specified protocol. The authors themselves are explicit on this point: while the findings suggest that the pragmatic follitropin delta regimen may offer clinical efficiency in progestin-protocol freeze-all cycles, well-designed prospective randomised controlled trials are required before it can be routinely recommended in clinical practice. The research received no external funding, and the authors declare no competing interests, with ethics approval granted by the Institutional Review Board of My Duc Hospital and patient consent waived given the anonymised, retrospective nature of the data.

Even with those caveats, the study marks a meaningful step in the evolution of personalised ovarian stimulation. Follitropin delta’s individualised algorithm, elegant on paper, has proven difficult to deploy in the protocols that now dominate modern IVF practice, especially freeze-all cycles built on progestin suppression. Demonstrating that a simple three-tier dosing scheme keyed to anti-Müllerian hormone can match the standard drug on live birth while shaving a day off stimulation offers clinics a practical, evidence-grounded option. If randomised trials confirm these results, the microgram-dosed hormone could move from a niche product constrained by its own dosing software to a mainstream tool for ovarian stimulation across the full spectrum of contemporary IVF protocols.

Subject of Research: Follitropin delta dosing for ovarian stimulation in IVF freeze-all cycles using a progestin protocol

Article Title: Novel follitropin delta dosing regimen during in vitro fertilisation using a progestin protocol and freeze-all strategy: a propensity score matching cohort study

Article References: Le, T. K., Nguyen, D. L., Pham, T. D., Le, H. L., Ho, V. N. A., Le, X. T. H., Vo, C. V., Nguyen, T. T. L., Ha, A. N., Ly, T. T., Huynh, B. G., Ho, T. M., & Vuong, L. N. (2026). Novel follitropin delta dosing regimen during in vitro fertilisation using a progestin protocol and freeze-all strategy: a propensity score matching cohort study. Journal of Ovarian Research. https://doi.org/10.1186/s13048-026-02292-7

Image Credits: AI Generated

DOI: 10.1186/s13048-026-02292-7

Keywords: follitropin delta, follitropin alfa, IVF, progestin protocol, freeze-all strategy, frozen embryo transfer, ovarian stimulation, anti-Müllerian hormone, live birth rate, ovarian hyperstimulation syndrome, propensity score matching, reproductive medicine

Ovarian stimulation is the engine of modern in vitro fertilization. For decades, the standard approach has been to start injectable gonadotrophins early in the menstrual cycle, typically on day two or three, and to co-administer a GnRH antagonist partway through the stimulation to prevent a premature surge of luteinizing hormone (LH). Such a surge would otherwise trigger ovulation before the eggs could be retrieved, ruining the cycle. The antagonist acts as a chemical clamp on the pituitary gland, blocking the receptors through which GnRH from the hypothalamus would normally instruct the release of LH and follicle-stimulating hormone. It is an effective safeguard, but it adds injections, cost, and monitoring complexity to an already demanding process.

Late follicular phase stimulation emerged as an alternative concept in the context of freeze-all strategies, in which no fresh embryo transfer takes place. Instead, all embryos are cryopreserved and transferred in a later, unstimulated or artificially prepared cycle. Because the transfer is decoupled from the stimulation, clinicians have more flexibility in how the stimulation itself is conducted. In a late stimulation protocol, gonadotrophins are not started at the beginning of the cycle but later, after a dominant follicle has already been selected by the body’s own hormonal signals. The idea is to recruit the cohort of antral follicles that is naturally available in that cycle while working with, rather than against, the endocrine rhythm of the ovary.

Until now, however, even late stimulation protocols have relied on exogenous pituitary modulators, usually a GnRH antagonist added once stimulation begins, to guard against a premature LH surge. Whether the antagonist could be dropped altogether in late stimulation was an open question, and robust randomized evidence was lacking. The new trial, led by Xiuxian Zhu, Jingwen Lang, and colleagues at Shanghai First Maternity and Infant Hospital affiliated with Tongji University School of Medicine, was designed to answer precisely that question using a non-inferiority framework, the appropriate statistical design when the goal is to show that a simpler treatment is not meaningfully worse than the standard one.

The researchers enrolled 300 infertile women with normal ovulatory function and randomized them one-to-one between February 2022 and October 2023. Half received the conventional GnRH antagonist protocol, with stimulation initiated in the early follicular phase and antagonist co-administration. The other half received the antagonist-free late stimulation protocol, in which gonadotrophin injections began later in the follicular phase without any pituitary-blocking drug. All participants were undergoing IVF or intracytoplasmic sperm injection (ICSI) with a freeze-all strategy, meaning every viable embryo was frozen for later transfer. The trial was registered with the Chinese Clinical Trial Registry (ChiCTR2200055972) and approved by the hospital’s ethics committee, with all participants providing written informed consent.

The primary outcome was the number of usable embryos, a measure that captures the clinically meaningful yield of a stimulation cycle better than raw egg counts alone. In the late stimulation group, the median number of usable embryos was 3 (interquartile range 1 to 5), while in the antagonist group it was also 3 (interquartile range 1 to 4). The median difference between groups was 0, with a 95 percent confidence interval of minus 1 to 0. The prespecified non-inferiority margin was set at the lower bound of that interval, and because the lower bound of minus 1 met the margin, the investigators concluded that the antagonist-free late protocol was non-inferior to the antagonist regimen. In practical terms, women who skipped the antagonist did not end up with fewer embryos fit for freezing and later transfer.

Several secondary outcomes added nuance to this headline result. The total number of oocytes retrieved did not differ significantly between the two groups, but the late stimulation group produced significantly more mature oocytes, with a median of 7 (interquartile range 4 to 10.25) compared with 5.5 (interquartile range 3 to 8) in the antagonist group, a difference that reached statistical significance at P equals 0.018. Maturity matters because only mature oocytes, those that have completed the first meiotic division, can be fertilized. A protocol that yields a higher proportion of mature eggs may therefore translate the same number of retrieved eggs into more embryos, which is consistent with the comparable usable embryo counts observed despite any differences in retrieval totals.

Pregnancy outcomes from the subsequent frozen embryo transfers leaned in favor of the late stimulation protocol, though not all differences were conclusive. The implantation rate, the proportion of transferred embryos that successfully implanted, was significantly higher in the late stimulation group at 68.15 percent versus 54.86 percent in the antagonist group (P equals 0.013). The clinical pregnancy rate was also numerically higher in the late stimulation group, 66.01 percent versus 55.36 percent, but this difference fell just short of statistical significance at P equals 0.051. Early miscarriage rates were comparable between the groups, at 14.85 percent and 12.9 percent respectively (P equals 0.695), providing reassurance that the simplified protocol did not compromise early pregnancy outcomes.

The biological rationale for these findings is worth unpacking. In a natural cycle, rising estradiol from the developing dominant follicle feeds back on the hypothalamus and pituitary, and the late follicular phase is characterized by a delicate interplay in which follicle-stimulating hormone is restrained while LH remains controlled until the mid-cycle surge. Starting gonadotrophins late, when a dominant follicle has already been selected, may allow the remaining cohort of smaller follicles to be recruited under conditions that more closely mimic natural physiology. The higher maturity rate of the retrieved oocytes in the late stimulation group suggests that the follicles developed in a more synchronized hormonal environment, possibly because the endogenous hormonal milieu was not flattened by antagonist administration from the earliest days of the cycle.

The authors caution that their study was a single-center trial conducted in normo-ovulatory women, a population whose regular cycles make them suitable candidates for a protocol that depends on the timing of natural follicular development. Women with irregular ovulation, such as those with polycystic ovary syndrome, may not be appropriate candidates, since the protocol relies on the body’s own selection of a dominant follicle. The investigators themselves state that larger multicenter trials are warranted to confirm the findings before the protocol can be considered for broad clinical adoption. Still, the trial, funded by the hospital, the National Natural Science Foundation of China, and the Science and Technology Commission of Shanghai Municipality, represents the first robust randomized evidence that late follicular phase stimulation can succeed without any exogenous pituitary modulator at all.

For patients, the implications are tangible. Removing the GnRH antagonist from a stimulation cycle means fewer daily injections, lower medication costs, and a simpler monitoring schedule, all without a measurable loss of usable embryos in this study population. For the freeze-all paradigm, which has grown rapidly because it avoids the ovarian hyperstimulation syndrome risk and endometrial asynchrony associated with fresh transfers, the late stimulation protocol offers a physiologically elegant complement: stimulate later, work with the cycle rather than suppressing it, freeze everything, and transfer later. As assisted reproduction continues to move toward personalized, less burdensome protocols, this Shanghai trial provides a data point suggesting that sometimes the best way to control the ovary is to trust it a little more.

Subject of Research: GnRH antagonist-free late follicular phase ovarian stimulation for freeze-all IVF/ICSI in normo-ovulatory women

Article Title: GnRH antagonist‑free late follicular phase ovarian stimulation versus an early follicular GnRH antagonist regimen in normo-ovulatory women undergoing freeze-all IVF/ICSI: a randomized controlled trial

Article References: Zhu, X., Lang, J., Zhi, Y., Wang, Q., & Fu, Y. (2026). GnRH antagonist‑free late follicular phase ovarian stimulation versus an early follicular GnRH antagonist regimen in normo-ovulatory women undergoing freeze-all IVF/ICSI: a randomized controlled trial. Journal of Ovarian Research. https://doi.org/10.1186/s13048-026-02285-6

Image Credits: AI Generated

DOI: 10.1186/s13048-026-02285-6

Keywords: IVF, ICSI, ovarian stimulation, GnRH antagonist, late follicular phase, freeze-all strategy, randomized controlled trial, fertility treatment, oocyte maturity, implantation rate, reproductive medicine, frozen embryo transfer

The study, led by Mohammed Khaled Al Alaili, took an unusually rigorous approach for an overview of this kind. The researchers systematically searched five databases to identify reviews of N-acetylcysteine that met predetermined inclusion and exclusion criteria, ultimately retrieving 140 separate reviews spanning the full breadth of clinical medicine. Rather than simply cataloguing these publications, the team extracted comprehensive data to map the evidence, and then applied two validated appraisal tools to assess methodological quality and risk of bias. This allowed them to stratify the evidence by how much confidence clinicians and researchers should actually place in it, a step that many broader reviews skip entirely.

One of the most striking findings concerns the hierarchy of evidence itself. Of the 140 reviews retrieved, only 63 were systematic reviews with meta-analysis, the design widely regarded as the highest level of synthesized evidence in medicine. The remainder were narrative or other less structured reviews, which are more vulnerable to selective citation and author bias. Among the 63 top-tier syntheses, roughly half supported repurposing N-acetylcysteine for new indications, a proportion that sounds encouraging until it is set against the quality appraisals. The critical appraisal revealed a high prevalence of critically low-quality systematic reviews, even as a notable proportion of reviews showed low risk of bias, a mismatch that underscores how uneven the field really is.

To quantify redundancy, the researchers calculated the corrected covered area, a metric designed to detect when multiple reviews cover the same primary studies, inflating the apparent volume of evidence without adding new information. The CCA analysis demonstrated substantial overlap and redundancy across domains, and particularly within subdomains. In practical terms, many of the 140 reviews were re-analyzing the same small pools of trials, a pattern the authors describe as possible research waste. This finding matters beyond N-acetylcysteine: it illustrates a systemic problem in evidence synthesis, where the incentive to publish reviews outpaces the production of new primary trials capable of settling clinical questions.

The biological case for repurposing N-acetylcysteine rests on its remarkable pleiotropy. Most frequently reported in the literature are its antioxidant properties: the drug replenishes glutathione, the cell’s principal endogenous antioxidant, thereby buffering the oxidative stress implicated in conditions ranging from neurodegeneration to chronic kidney disease. Alongside this, the review catalogued well-supported anti-inflammatory effects and an increasingly studied role in modulating glutamatergic signaling, the neurotransmitter system implicated in compulsive behavior, addiction, and several psychiatric disorders. Beyond these three headline mechanisms, the authors note that several additional mechanisms have been proposed, reflecting the molecule’s involvement in fundamental cellular pathways rather than any single disease-specific target.

The geographic and temporal patterns in the literature are equally revealing. The number of N-acetylcysteine reviews has increased over time, mirroring the broader surge of interest in drug repurposing and oxidative stress as therapeutic frontiers. Most of these reviews originated from China and the United States, a concentration that may shape which questions get asked and which patient populations the evidence reflects. Drug repurposing has become one of the most attractive strategies in pharmaceutical research because established agents come with known safety profiles, existing manufacturing capacity, and often low cost, and N-acetylcysteine exemplifies all three advantages, making the gap between research enthusiasm and clinical implementation all the more conspicuous.

From the mapped landscape, five clinical domains emerged as priorities for future exploration: psychiatry, reproductive medicine, nephrology, pulmonology, and toxicology. Each of these fields has plausible mechanistic rationale for benefit. In psychiatry, glutamatergic modulation offers a testable pathway for disorders of compulsion and mood. In reproductive medicine, oxidative stress is a recognized contributor to fertility problems and pregnancy complications. In nephrology and pulmonology, antioxidant and anti-inflammatory actions align with the pathophysiology of chronic organ injury, while toxicology already has one firmly established use, the treatment of paracetamol poisoning, that demonstrates the drug can change outcomes decisively when the evidence is strong enough.

What holds the field back, according to the review, is not a shortage of hypotheses but a shortage of certainty. The overall inconsistency in review certainty remains a barrier to integrating N-acetylcysteine into clinical guidelines, because guideline committees require consistent, high-quality evidence before recommending a therapy for new indications. A landscape in which half of the top-tier reviews support repurposing while a large share of all reviews are critically low in quality gives committees little to work with. The redundancy documented by the CCA analysis compounds the problem, since overlapping syntheses can create an illusion of consensus where the underlying trial base is thin, heterogeneous, or outdated.

The authors argue that the way forward requires precision medicine approaches to guide future clinical implementation and research. Rather than testing N-acetylcysteine as a one-size-fits-all intervention, future trials could stratify patients by oxidative stress burden, genetic determinants of glutathione metabolism, or disease subtype, identifying the populations most likely to benefit. Such targeting could also resolve some of the heterogeneity that has plagued meta-analyses, in which mixed patient groups and variable dosing regimens make pooled estimates difficult to interpret. By delineating research priorities and highlighting new avenues, the review functions as both a map of what is known and a checklist of what must be done before the drug’s promise can be translated into practice.

For clinicians and patients, the immediate takeaway is one of cautious patience. N-acetylcysteine remains a valuable and well-established therapy in its approved roles, particularly in airway disease and acetaminophen toxicity, and its safety record makes further study attractive. But the new analysis makes clear that the sprawling literature celebrating its potential has outpaced the rigorous trials needed to confirm it. The review’s contribution is to convert that sprawling enthusiasm into an organized agenda: prioritize the five highest-potential domains, replace redundant reviews with well-designed primary trials, and apply the same methodological scrutiny to repurposing evidence that regulators demand for novel drugs. If that agenda is followed, a molecule first synthesized in the nineteenth century may yet find a second, better-evidenced life in twenty-first-century medicine.

Subject of Research: Drug repurposing potential and evidence quality of N-acetylcysteine across clinical domains

Article Title: Repurposing landscape of N-acetylcysteine: A scoping review of reviews toward clinical translation

Article References: Al Alaili, M. K. (2026). Repurposing landscape of N-acetylcysteine: A scoping review of reviews toward clinical translation. PLOS One, 21(10), e0360434. https://doi.org/10.1371/journal.pone.0360434

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360434

Keywords: N-acetylcysteine, drug repurposing, scoping review, oxidative stress, systematic reviews, glutathione, evidence quality, research waste, psychiatry, reproductive medicine, nephrology, toxicology