Association between surgically diagnosed endometriosis and adverse pregnancy outcomes.

Objective: To examine the association between surgically diagnosed endometriosis and pregnancy outcomes in subsequent pregnancies.

Design: Retrospective cohort study of women who delivered a singleton live birth from 2003 to 2013 in Ottawa, Ontario, Canada.

Setting: Tertiary level academic center.

Patient(s): Pregnant women with surgically diagnosed endometriosis were identified using International Classification of Diseases-10 codes from previous hospital admissions and were compared with pregnant women with no prior admission for endometriosis for the occurrences of adverse pregnancy outcomes.

Intervention(s): Observational study.

Main Outcome Measure(s): Gestational hypertension, preeclampsia, placenta previa, placental abruption, postpartum hemorrhage, preterm birth, low birth weight, small for gestational age, and neonatal intensive care unit admission.

Results: Among the 52,202 eligible mother-infant pairs, we identified 469 mothers with surgically diagnosed endometriosis from a previous hospital encounter. Compared with women without endometriosis, women with endometriosis were on average older and were more likely to be primiparous, have lower gravidity, have a history spontaneous abortion, conceive with assisted reproductive technology, and reside in areas with higher neighborhood income and lower proportion of immigrants. Women with endometriosis were found to have an elevated risk of placenta previa (relative risk [RR], 3.30; 95% confidence interval [CI], 1.65-5.40) and cesarean delivery (RR, 1.24; 95% CI, 1.10-1.40). After adjustment for potential confounding factors, women with endometriosis were found to have a significantly elevated risk of placenta previa compared with women without endometriosis (adjusted RR, 2.54; 95% CI, 1.39-4.64).

Conclusion(s): This study identifies baseline demographic differences between women with and without endometriosis and suggests that women affected by endometriosis have an independently elevated risk of placenta previa in pregnancy.