Endometriosis, pregnancy and delivery complications: Evidence from the US nationwide inpatient sample 2005–2018

Endometriosis is associated with higher risk of ectopic pregnancy, premature delivery, miscarriage, and other adverse maternal and fetal complications. This study aimed to assess the impact of endometriosis on maternal and fetal outcomes of singleton pregnancies in a large nationally representative database. This population-based, retrospective observational study extracted the data of women aged 20–49 years with singleton, spontaneously conceived pregnancies from the US Nationwide Inpatient Sample (NIS) database from 2005 to 2018. Included subjects were divided into those with ICD codes for endometriosis and those without (non-endometriosis group). Data of maternal and fetal outcomes were compared between groups and analyzed using regression analysis. After excluding 17,124 women who conceived with assisted reproductive technology (ART), 162,155 women with multiple pregnancies, and 27,847 with abnormal trend weight values (TRENDWT), a total of 8,584,269 women were eligible. After propensity score matching (PMS) case–control 1:4 by age, 45,560 remained (9112 (0.1%) with endometriosis, 36,448 without) and were included in the analysis. The mean age of women before matching was 28.7 years, and 30.5 years after matching. The most common comorbidity was chronic pulmonary disease (3.6%). Smoking frequency was higher in women with endometriosis compared to those without (4.8% vs. 2.4%). Multivariable analysis adjusted for confounders revealed that endometriosis was associated with significantly higher risk of maternal complications, including pre-eclampsia and eclampsia, antepartum hemorrhage, placenta previa, Cesarean delivery, post-partum hemorrhage, disseminated intravascular coagulation (DIC), transfusion, hemoperitoneum, and hospital stays ≥6 days. For fetal outcomes, endometriosis was associated with higher risk of intrauterine growth restriction (IUGR), premature birth, birth defects and abortion. Endometriosis during pregnancy is associated with maternal and fetal complications. Study findings may serve as a benchmark for expanding medical assistance for endometriosis-affected pregnant women.