Endometriosis and pregnancy complications: a Danish cohort study.

OBJECTIVE: To study the association between endometriosis and risk of pre-eclampsia, cesarean section, postpartum hemorrhage, preterm birth, and small for gestational age (SGA), in a large Danish birth cohort, while taking fertility treatment into account.

DESIGN: Population-based study.

SETTING: Not applicable.

PATIENT(S): A total population of 82,793 singleton pregnancies from the Aarhus Birth Cohort (1989 through 2013); 1,213 women had a diagnosis of endometriosis, affecting 1,719 pregnancies.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Pre-eclampsia, cesarean section, postpartum hemorrhage, preterm birth, and SGA.

RESULT(S): Endometriosis was associated with an increased risk of preterm birth (adjusted odds ratio [AOR] 1.67, 95% confidence interval [CI] 1.37-2.05), with the risk being highest for very preterm birth (AOR 1.91, 95% CI 1.16-3.15). Compared with unaffected women, women with endometriosis also had an increased risk of pre-eclampsia (AOR 1.37, 95% CI 1.06-1.77) and cesarean section (AOR 1.83, 95% CI 1.60-2.09). Assisted reproductive technology did not explain these findings. No association was found between endometriosis and postpartum hemorrhage or SGA.

CONCLUSION(S): Women with endometriosis were at increased risk of pre-eclampsia, preterm birth, and cesarean section, irrespective of use of assisted reproductive technology.