The study divided participants into three groups. The first comprised 128 women who had undergone surgical multifetal pregnancy reduction, a procedure in which one or more gestational sacs are deliberately interrupted to leave a single developing fetus. The second included 156 women whose pregnancies had undergone spontaneous fetal reduction, the natural loss of one embryo or gestational sac in a multiple pregnancy. The third, and by far the largest, was a control group of 1,167 women whose pregnancies had been singleton from the outset.

The researchers compared baseline characteristics, maternal complications, and neonatal outcomes across the three groups, then used multivariate logistic regression to isolate the independent contribution of each reduction pathway. The statistical models adjusted for maternal age, pre-pregnancy body mass index, embryo type, the number of embryos transferred, and embryo stage.

Unadjusted comparisons showed significant intergroup differences in two key outcomes. Gestational diabetes mellitus was most frequent in the spontaneous reduction group, affecting 26.92 percent of those women, compared with 19.53 percent in the surgical reduction group and 15.94 percent in the initial singleton controls, a difference that reached statistical significance at P = 0.003. Preterm birth followed a similar gradient, occurring in 19.23 percent of spontaneous reduction pregnancies, 14.06 percent of surgical reduction pregnancies, and 11.83 percent of controls, with P = 0.024.

The groups did not differ significantly in the incidence of hypertensive disorders of pregnancy, placental complications, or congenital birth defects.

Once the data were adjusted for confounders, the picture changed in an important way. Neither surgical reduction, with an odds ratio of 1.22 (95 percent confidence interval 0.98 to 1.52, P = 0.069), nor spontaneous reduction, with an odds ratio of 1.39 (95 percent confidence interval 0.98 to 1.98, P = 0.067), was an independent risk factor for gestational diabetes in this cohort.

The only independent predictors of gestational diabetes in this cohort were advanced maternal age, with an odds ratio of 1.12 (95 percent confidence interval 1.01 to 1.23, P = 0.028), and elevated pre-pregnancy body mass index, with an odds ratio of 1.11 (95 percent confidence interval 1.01 to 1.21, P = 0.030).

Preterm birth told a different story. After adjustment, both reduction modalities remained independently associated with higher odds of early delivery. Surgical reduction carried an odds ratio of 1.35 (95 percent confidence interval 1.09 to 1.68, P = 0.007), while spontaneous reduction carried a numerically higher odds ratio of 1.72 (95 percent confidence interval 1.20 to 2.45, P = 0.003). The authors emphasize that although the adjusted estimate was larger for spontaneous reduction, a direct statistical comparison between the two methods showed no significant difference, so the data cannot establish that one pathway is riskier than the other.

The authors conclude that in singleton live births after assisted reproductive technology, a history of fetal reduction, whether surgical or spontaneous, was not independently associated with gestational diabetes, but both reduction modalities were independently associated with higher odds of preterm birth.

As a retrospective single-center cohort, the study cannot prove causation, and its findings may not generalize beyond this population. The results indicate that, among these ART singleton live births, maternal age and pre-pregnancy body mass index predicted gestational diabetes, while a history of either form of fetal reduction predicted preterm delivery.

Subject of Research: Maternal and neonatal outcomes after surgical versus spontaneous fetal reduction in assisted reproductive technology pregnancies

Article Title: Impact of surgical versus spontaneous fetal reduction on maternal and neonatal outcomes after assisted reproductive technology: a single-center cohort study of 1, 451 singleton live births

Article References: Song, J., Zhang, T., Wang, K., Liu, Z., & Li, C. (2026). Impact of surgical versus spontaneous fetal reduction on maternal and neonatal outcomes after assisted reproductive technology: a single-center cohort study of 1, 451 singleton live births. Frontiers in Endocrinology, 17, Article 1923529. https://doi.org/10.3389/fendo.2026.1923529

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1923529

Keywords: assisted reproductive technology, fetal reduction, spontaneous fetal reduction, preterm birth, gestational diabetes mellitus, singleton pregnancy, cohort study, multifetal pregnancy reduction, maternal outcomes, neonatal outcomes, Impact, surgical