Mothers and pregnant people with endometriosis face a modestly higher risk of having infants with certain congenital birth defects, according to a new study.

The findings provide critical insight into how chronic maternal conditions may influence fetal development, potentially allowing healthcare providers to offer more targeted prenatal monitoring for affected families.

The research, published Monday, May 8, analyzed a population-based cohort of more than 1.4 million births [1] in Ontario, Canada. The data covered births occurring between April 7, 2006, and March 31, 2021 [2]. Researchers found that endometriosis is associated with a slight increase in the likelihood of specific anomalies, most notably pulmonary artery stenosis, hypospadias, and unspecified cleft palate.

Numerical data from the study indicates a 1.5-fold, or 50%, increase in the risk for pulmonary artery stenosis [3]. The risk for hypospadias was approximately 1.4-fold, or 40% higher [4], while the risk for unspecified cleft palate was approximately 1.3-fold, or 30% higher [4].

"Our findings suggest that endometriosis is associated with a modest increase in the risk of certain congenital anomalies," said lead author Dr. Emily L. McDonald [4].

Despite these findings, experts caution against alarm. Genevieve Beauchemin of CTV National News said women with endometriosis should be aware of the risk, but noted it does not mean they will definitely have a baby with a defect [2].

The study also highlighted a gap in diagnosis. While the expected prevalence of endometriosis in reproductive-aged women is about 10%, the prevalence within this specific cohort was only 2.3% [5]. Dr. Sarah Patel said this discrepancy possibly reflects under-diagnosis of the condition [5].

“Endometriosis is associated with a modest increase in the risk of certain congenital anomalies.”

This research identifies endometriosis as a potential risk factor for specific congenital anomalies, though the absolute risk remains low. The significant gap between the observed 2.3% prevalence in the cohort and the expected 10% prevalence in the general population suggests that many women remain undiagnosed, which may obscure the full scale of these risks in broader clinical settings.