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 cesarean 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, cesarean 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 cesarean 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). CONCLUSION: In primiparous women, pre-existing endometriosis was independently associated with placenta previa, but not with preterm birth or cesarean delivery. These findings support abnormal early placentation as a potential mechanism linking endometriosis to adverse obstetric outcomes.