Endometriosis and adverse pregnancy outcomes in primiparous women: a retrospective cohort study

Objective To assess whether pre-existing endometriosis is associated with specific adverse pregnancy and delivery outcomes in primiparous women Design Retrospective cohort study Setting Tertiary care university hospital Population or Sample Primiparous women with singleton pregnancies. Methods Women with endometriosis were compared with primiparous controls without endometriosis. Primary outcomes were preterm birth and caesarean delivery; placenta previa was examined as a key secondary outcome. Multivariable logistic regression models adjusted for maternal age and mode of conception were used. Main Outcome Measures Preterm birth, caesarean delivery, placenta previa. Results Among 16,033 primiparous women, 118 had a diagnosis of endometriosis prior to pregnancy. After adjustment for maternal age and mode of conception, endometriosis was not independently associated with preterm birth (adjusted odds ratio 0.75; 95% confidence interval 0.44-1.28) or caesarean delivery (adjusted odds ratio, 1.17; 95% confidence interval, 0.81–1.71). In contrast, endometriosis was associated with placenta previa (adjusted odds ratio, 5.90; 95% confidence interval, 2.37–14.71). Conclusions In primiparous women, pre-existing endometriosis was independently associated with placenta previa, but not with preterm birth or caesarean delivery. These findings support abnormal early placentation as a potential mechanism linking endometriosis to adverse obstetric outcomes. Funding None.