Risk of postpartum depression among women with endometriosis: the Norwegian mother, father and child cohort study (MoBa).

Women with endometriosis have a higher burden of anxiety and depression. Whether they are at increased risk of postpartum depression (PPD) remains unclear. We aimed to compare the risk of PPD between women with and without endometriosis and to explore mediation by previous history of major depression and infertility. In a population-based cohort study, we compared 1,159 singleton pregnancies to women with self-reported endometriosis and 74,590 pregnancies to women without endometriosis. We calculated a djusted risk ratios (aRR) with 95% confidence intervals (CI) using multivariable log-binomial regression, adjusting for age, body mass index, education and income. Mediation analyses assessed the indirect effect of any history of major depression or infertility. Women with endometriosis had a higher risk of PPD (aRR: 1.34, 95% CI: 1.15-1.55). Mediation analyses indicated that a large part of this association was explained by a higher lifetime prevalence of major depression among women with endometriosis (natural direct effect of endometriosis: aRR: 1.17, 95% CI: 1.00-1.36; natural indirect effect of any history of major depression: aRR: 1.14, 95% CI: 1.08-1.20), with 49.3% proportion mediated. Infertility demonstrated a negative natural indirect effect on the association between endometriosis and PPD (aRR: 0.87, 95% CI: 0.81-0.94). Women with endometriosis had an elevated risk of PPD which was largely explained by a higher lifetime prevalence of major depression. Our findings suggest that they constitute a high-risk group and could benefit from closer follow-up to facilitate early identification and intervention.