Association of Endometriosis and Severe Maternal Morbidity

To evaluate the association between endometriosis and risk of severe maternal morbidity (SMM).

We conducted a population-based retrospective cohort study of 2,412,823 deliveries at hospitals in Quebec, Canada, between 1989 and 2019. The exposure was surgically confirmed endometriosis. Patients were classified as having active endometriosis during pregnancy, inactive endometriosis during pregnancy, a diagnosis of endometriosis postpregnancy, or no endometriosis. The outcome was SMM, including by a range of life-threatening maternal conditions during pregnancy or up to 42 days postdelivery. We computed rates of SMM and used log binomial regression to assess the association with endometriosis (risk ratio [RR]; 95% CI), adjusted for maternal characteristics.

Severe maternal morbidity occurred in 46.2 of 1,000 patients with endometriosis, compared with 30.7 of 1,000 patients without endometriosis. Relative to no exposure, endometriosis was associated with 1.43 times the risk of SMM (95% CI 1.36-1.51). Patients with endometriosis that was active during pregnancy had a greater risk of SMM (RR 1.93; 95% CI 1.76-2.11). Active endometriosis was associated with the risk of severe preeclampsia and eclampsia, severe hemorrhage, hysterectomy, cardiac complications, embolism, shock, sepsis, and intensive care unit admission. Inactive endometriosis was less strongly associated with these outcomes.

Pregnant patients with endometriosis, especially active endometriosis, have a greater risk of SMM and may benefit from closer follow-up to prevent severe complications of pregnancy.