Babies born to women with endometriosis may face a 16% higher relative risk of congenital anomalies, according to a large Canadian population-based study.
A new Canadian observational study analyzing over 1.4 million births in Ontario from 2006 to 2021 has found a statistically significant link between endometriosis and birth defects. The findings, published recently, offer important context for understanding this complex relationship.
Key Findings
- Among infants with congenital anomalies, 6.3% had a parent with endometriosis, compared with 5.4% among those without anomalies. This translates to a relative risk (RR) of 1.16.
- The most common defects associated with endometriosis included cleft palate (RR 1.52), hypospadias (RR 1.47), and pulmonary artery stenosis (RR 1.41).
- Women with endometriosis were significantly more likely to have conceived via IVF (10.6% vs 1.5%), but the study found the association between endometriosis and birth defects was independent of IVF.
Context and Adjustments
Researchers took a rigorous approach, adjusting for a wide range of potential confounding factors, including maternal age, diabetes, high blood pressure, smoking, alcohol and substance use, obesity, and income.
- About 11% of the increased risk was explained by the use of IVF or ICSI. Other fertility treatments did not appear to mediate the relationship.
- The absolute risk remains low, and experts stress that the findings require further investigation rather than immediate alarm.
Expert Commentary
While the study's scale is a major strength, experts caution against over-interpretation.
Dr. Tal Jacobson noted that the study's size is impressive but highlighted limitations: the low prevalence of diagnosed endometriosis in the study (2.3% of mothers, versus an expected ~10%) and potential errors in hospital databases could skew results.
Dr. Kelsi Dodds added that the underdiagnosis of endometriosis could mean the true risk might be lower than reported.
Both experts agreed that the findings should not deter women with endometriosis from having children. Instead, they should encourage more targeted research to better understand the underlying mechanisms.