A 12-year cohort study on adverse pregnancy outcomes in Eastern Townships of Canada: impact of endometriosis

The aim of this study was to provide a temporal-spatial reference of adverse pregnancy outcomes (APO) and examine whether endometriosis promotes APO in the same population. Among the 31 068 women who had a pregnancy between 1997 and 2008 in Eastern Townships of Canada, 6749 (21.7%) had APO. These APO increased significantly with maternal age and over time (r(2)=0.522, p=0.008); and were dominated by preterm birth (9.3%), pregnancy-induced hypertension (8.3%) including gestational hypertension (6.5%), low birth weight (6.3%), gestational diabetes (3.4%), pregnancy loss (2.2%) including spontaneous abortion (1.5%) and stillbirth (0.6%), intrauterine growth restriction (2.1%) and preeclampsia (1.8%). Among the 31 068 pregnancies, 784 (2.5%) had endometriosis and 183 (23.3%) had both endometriosis and APO. Endometriosis has been shown to increase the incidence of fetal loss (OR =2.03; 95% Cl =1.42-2.90, p< 0.0001), including spontaneous abortion (OR =1.89; 95% CI =1.23-2.93, p=0.005) and stillbirth (OR =2.29; 95% CI =1.24-5.22, p = 0.012). This study provides a temporal-spatial reference on APO, which is a valuable tool for monitoring, comparing and correcting. It is also the first study to highlight an impact of endometriosis on the incidence of spontaneous abortion and stillbirth.