One in 4,000 US Infants Diagnosed With Congenital Lung Malformations, National Study Finds

Congenital lung malformations, a family of structural abnormalities that form while a baby’s lungs are still developing in the womb, have long been a familiar sight on prenatal ultrasound screens. Yet despite their prominence in fetal imaging and pediatric surgery, reliable national figures on how often these conditions actually occur, and how often surgeons operate on them, have been surprisingly hard to come by. A new retrospective database study from researchers at Stanford University School of Medicine and Lucile Packard Children’s Hospital, published in BMC Pediatrics, now offers the first contemporary, population-based snapshot of congenital lung malformations among infants in the United States, and its findings are already prompting clinicians to rethink patterns of diagnosis and treatment across the country.

The research team, led by pediatric surgeons Madeline Adams, Stephanie D. Chao, and Marisa E. Schwab, turned to the MarketScan Commercial Database, a large insurance claims repository that captures detailed billing records from privately insured patients across all fifty states. Using the International Classification of Diseases, Tenth Revision diagnostic codes assigned to congenital lung malformations between 2017 and 2023, the investigators identified affected patients and then required confirmation through cross-sectional chest imaging billed under the corresponding Current Procedural Terminology codes. This two-step approach, pairing a diagnostic code with objective imaging evidence, was designed to filter out coding noise and ensure that the cases counted in the analysis represented genuinely identified malformations rather than administrative artifacts.

The headline number that emerged from the analysis was a prevalence of 2.15 cases per 10,000 patients, which translates roughly into one diagnosed congenital lung malformation for every 4,650 infants in the commercially insured population. That figure may sound modest, but in a nation with roughly 3.6 million annual births it implies thousands of new diagnoses each year, making congenital lung malformations an important index condition for pediatric surgical services. The study also traced how detection changed over the study window: prevalence climbed from 1.80 per 10,000 in 2017 to a peak of 2.67 per 10,000 in 2020 before settling back in subsequent years. Intriguingly, when the researchers built a multivariate model adjusting for other factors, the year of birth itself was no longer a statistically significant predictor of diagnosis, suggesting that the apparent rise and fall may reflect shifting screening practices, coding conventions, or the disruptions of the COVID-19 pandemic era rather than a true change in the underlying biology.

One of the most striking findings in the adjusted model concerned geography. Infants living in the Southern United States were significantly less likely to be diagnosed with a congenital lung malformation than infants elsewhere in the country, with an adjusted prevalence ratio of 0.72 and a 95 percent confidence interval of 0.53 to 0.97, a difference the authors reported as statistically significant at p equals 0.03. In practical terms, this means that after accounting for other variables, babies in the South were diagnosed at roughly 28 percent lower rates than their counterparts in other regions. The study did not identify the mechanism behind this disparity, but the possibilities are consequential: differences in prenatal screening uptake, access to high-resolution fetal ultrasound and fetal magnetic resonance imaging, referral patterns to pediatric surgical centers, or variation in insurance coverage and healthcare-seeking behavior could all contribute. Whatever the cause, the authors note that such regional variation carries clear equity implications for which infants get identified and treated early.

Congenital lung malformations encompass several distinct entities, the most commonly discussed being congenital pulmonary airway malformation, formerly known as congenital cystic adenomatoid malformation, along with bronchogenic cysts, pulmonary sequestration, and hybrid lesions that combine features of more than one type. These malformations arise from errors in early embryonic lung development, when the branching airway tree is forming, and they can range from tiny, asymptomatic lesions discovered incidentally to large masses that compress surrounding lung tissue, shift the mediastinum, and cause respiratory distress in newborns. Many are now caught before birth, because routine second-trimester prenatal ultrasound frequently visualizes echogenic or cystic lung lesions, and specialized centers follow suspicious findings with fetal MRI and serial ultrasound measurements. Specialists sometimes calculate a CPAM volume ratio, a measurement that compares the size of the lesion to the fetal head circumference, to stratify the risk of hydrops and guide the intensity of prenatal surveillance.

What happens after diagnosis, however, has been the subject of genuine clinical debate. Some malformations cause trouble immediately, producing breathing difficulty, recurrent infections, or air trapping that demands prompt surgical resection. Others remain silent for years, and for those lesions the question of whether to operate prophylactically, to prevent future infection or, more controversially, to address a small reported risk of malignant transformation, versus pursuing watchful waiting with serial imaging, remains unsettled in the literature. The new study provides a valuable dose of national data on what actually happens in practice: among infants diagnosed with a congenital lung malformation, 47.72 percent underwent surgical resection. In other words, just under half of diagnosed infants had their lesion removed, while the other half were apparently managed without an operation during the observation window, a split that mirrors the ongoing tension between operative and nonoperative management strategies.

Timing of surgery emerged as another clear pattern. Of the infants who did undergo resection, 96.18 percent had their operation during the first year of life, underscoring that when American pediatric surgeons decide to operate on these lesions, they overwhelmingly do so early rather than deferring intervention into later childhood. This preference for early resection reflects several practical considerations: lesions are often easier to remove before they have caused repeated infections or scarring, compensatory lung growth in infancy may be more robust after lobectomy, and families and clinicians alike often prefer to resolve uncertainty while the child is young. Yet the study also detected a trend over the study period toward decreasing resection rates, hinting that the pendulum may be swinging, at least modestly, toward more conservative management as clinicians gain confidence in surveillance protocols for asymptomatic lesions and as shared decision-making with families becomes more common.

Perhaps the most unexpected finding concerned where the operations took place. Among infants who underwent resection, 21.21 percent received their surgical care in a state different from their home state, meaning that more than one in five families crossed state lines for their child’s lung surgery. This migration of care is a powerful signal of how concentrated specialized pediatric surgical expertise has become. Congenital lung resection, whether performed open or thoracoscopically, demands pediatric anesthesiologists, neonatal intensive care capacity, and surgeons with specific thoracic experience, resources that exist at a limited number of children’s hospitals. Families who live far from such centers may travel hundreds of miles, absorbing significant costs and logistical burdens, and the authors point out that this migration may reshape healthcare utilization patterns in ways that policy makers have not fully accounted for. It also raises equity questions, because families with the means, flexible jobs, and insurance networks to travel may access high-volume expert centers while others may not.

The study’s methodology deserves attention from anyone interpreting its numbers. MarketScan captures commercially insured patients, which means the findings may not generalize perfectly to infants covered by Medicaid or the uninsured, populations that skew differently demographically and geographically. Claims data also cannot capture the full clinical picture: the study cannot distinguish reliably among malformation subtypes, cannot measure lesion size or the presence of symptoms, and cannot reveal why any individual family or surgeon chose surgery or surveillance. The prevalence figure of 2.15 per 10,000 is best understood as a diagnosed prevalence within a privately insured population rather than a true birth prevalence of the underlying malformations, since some lesions likely go undetected and some affected pregnancies do not result in live birth. Still, by requiring imaging confirmation and analyzing seven years of national data, the study sets a firmer baseline than the small single-center series that have dominated the literature.

For clinicians, the takeaways are concrete. The declining resection trend suggests that nonoperative management is gaining real-world traction, which should prompt continued development of evidence-based surveillance protocols and longer-term outcome data on children managed without surgery. The regional diagnostic gap in the South is a call to examine prenatal screening access and referral pathways, because a malformation that goes undiagnosed in infancy may still declare itself later with infection or other complications. And the substantial interstate migration for surgery highlights the need for thoughtful regionalization of pediatric thoracic care, paired with support systems that make expert care reachable for families regardless of zip code. As the first contemporary population-based study of its kind in the United States, this analysis does not settle the clinical debates around congenital lung malformations, but it gives the field something it has lacked: a national map of where things stand today, drawn from the real-world experiences of thousands of infants and their families.

Subject of Research: National prevalence and surgical management of congenital lung malformations among US infants

Article Title: A database study of contemporary diagnosis and management among infants with congenital lung malformations in the United States

Article References: Adams, M., Chao, S. D., & Schwab, M. E. (2026). A database study of contemporary diagnosis and management among infants with congenital lung malformations in the United States. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07785-4

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07785-4

Keywords: congenital lung malformations, pediatric surgery, prenatal diagnosis, CPAM, MarketScan database, epidemiology, healthcare disparities, thoracic surgery, infant health, insurance claims data, regionalization of care, BMC Pediatrics