A major new study published in Canadian Medical Association Journal has found that infants born to patients with endometriosis may face a slightly higher risk of congenital anomalies compared with infants born to patients without the condition.
The research, titled Risk of congenital anomalies among infants of patients with endometriosis: a population-based cohort study, analyzed more than 1.4 million births in Ontario, Canada, over a 15 year period. Researchers discovered that while the overall risk remains relatively low, endometriosis was associated with a statistically significant increase in several birth defects, particularly cardiovascular and genital anomalies.
This study adds to growing evidence that endometriosis affects more than fertility and pelvic pain. It may also influence pregnancy outcomes and fetal development.
Endometriosis is a chronic inflammatory condition where tissue similar to the uterine lining grows outside the uterus. It commonly affects the ovaries, fallopian tubes, and pelvic tissue.
Symptoms may include:
According to previous estimates, endometriosis affects roughly 1 in 10 reproductive age women worldwide. Many patients experience years of delayed diagnosis because symptoms are often misunderstood or normalized.
The population based cohort study reviewed 1,460,564 births between 2006 and 2021. Among these pregnancies, 33,619 patients had a diagnosis of endometriosis.
Researchers found:
After adjusting for factors such as maternal age, obesity, diabetes, smoking, hypertension, and socioeconomic status, researchers found a 16% increased relative risk of congenital anomalies among infants exposed to maternal endometriosis.
The study also identified increased risks for several specific conditions.
Researchers observed higher rates of several congenital anomalies, including:
Infants had increased risks of:
Male infants showed higher rates of:
The study also found an increased risk of unspecified cleft palate.
Although the relative risks increased, researchers emphasized that congenital anomalies remained uncommon overall.
One of the most important findings involved fertility treatment mediation.
Because endometriosis is strongly linked to infertility, many patients undergo assisted reproductive technologies such as:
The study found that IVF and ICSI explained only about 11% of the increased congenital anomaly risk. This means most of the association appeared to exist independently of fertility treatment itself.
Researchers concluded that endometriosis may directly contribute to abnormal fetal development through biological mechanisms unrelated to assisted reproduction.
Scientists are still investigating why endometriosis may increase congenital anomaly risk.
Several theories include:
Endometriosis creates persistent inflammation throughout the body. Chronic inflammatory responses may interfere with normal embryonic development during the first trimester.
Oxidative stress can damage cells and DNA during organ formation, potentially increasing developmental abnormalities.
The study referenced emerging evidence that inflammation related to endometriosis may alter DNA methylation and developmental gene expression in embryos.
Endometriosis has also been associated with abnormal placental development, which may affect fetal growth and organ formation.
This study is one of the largest investigations to date examining endometriosis and congenital anomalies. It provides important insights for:
The findings do not suggest that people with endometriosis should avoid pregnancy. Instead, the research highlights the importance of individualized prenatal care and informed counseling.
Patients with endometriosis may benefit from:
While headlines about birth defects can sound alarming, the actual increase in risk was relatively modest.
For example:
Researchers repeatedly emphasized that the findings should not create unnecessary fear for patients with endometriosis.
Instead, the study contributes to a broader understanding of how chronic inflammatory diseases may influence reproductive outcomes.
The study included:
Researchers also acknowledged limitations:
Despite these limitations, sensitivity analyses produced similar findings, strengthening confidence in the results.
If you have endometriosis and are planning pregnancy, this research should be viewed as informative rather than alarming.
Experts recommend:
Many patients with endometriosis have healthy pregnancies and healthy babies.
The study simply suggests that clinicians may need to monitor certain pregnancies more closely and continue researching the biological pathways connecting endometriosis with fetal development.
The new Canadian study provides compelling evidence that endometriosis may modestly increase the risk of congenital anomalies in infants, even after accounting for infertility and fertility treatments.
Although the exact mechanisms remain unclear, inflammation, oxidative stress, and epigenetic changes are likely contributors. Researchers stress that the overall risk remains low, but the findings may help improve prenatal care strategies and future reproductive research.
As awareness of endometriosis continues to grow globally, studies like this are essential for helping patients and healthcare providers make informed reproductive decisions.
Milne B, Velez MP, Shellenberger J, Brogly SB. Risk of congenital anomalies among infants of patients with endometriosis: a population-based cohort study. Canadian Medical Association Journal. Published May 11, 2026. DOI: 10.1503/cmaj.250439
This article is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding medical concerns, pregnancy planning, fertility treatment, or endometriosis management.
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