Postpartum depression in relation to chronic diseases and multimorbidity in women's mid-late life: a prospective cohort study of UK Biobank.

Background: Maternal short-term outcomes of postpartum depression (PPD) were widely examined, but little is known about its long-term association with multiple chronic diseases (multimorbidity) in women's later life. This study aims to assess the association of PPD with chronic diseases and multimorbidity in women's mid-late life.

Methods: This prospective cohort study included female participants in UK Biobank who attended online follow-up assessment and reported their history of PPD. A total of 36 chronic diseases were assessed and multimorbidity was defined as the co-existence of two or more of these diseases. Participants were followed from the baseline recruitment to the onset of two or more chronic diseases, death, or the end of follow-up (2023). Logistic regression models, Cox proportional hazard models, quasi-Poisson mixed effects models, and linear mixed models were conducted to examine the association of PPD with chronic diseases and multimorbidity at baseline and during follow-up.

Results: Among all 54,885 participants, 5106 (9.3%) participants experienced PPD, 13,928 (25.4%) participants had multimorbidity at baseline, and 14,135 (25.8%) participants developed two or more diseases during a median follow-up of 15 years. Women with a PPD history had higher odds of having multimorbidity at baseline (odds ratio = 1.35, 95% confidence interval [CI] = 1.27-1.44) and higher risk of developing multimorbidity during follow-up (hazard ratio = 1.13, 95% CI = 1.08-1.20). PPD was associated with increased number of chronic diseases, with the relatively new-onset number of diseases during follow-up being 8% higher for those with PPD (relative risk = 1.08, 95% CI = 1.05-1.12). Chronic diseases also accumulated at a faster annual rate for women with a history of PPD (b = 0.009, 95% CI = 0.007-0.011), compared to those without. We observed no interaction or mediation effects of physical activity, smoking, alcohol drinking, and dietary factors on the association between PPD and multimorbidity; however, women's body mass index at baseline contributed to the association, with the mediation proportion of 6.38% (2.56-10.20%).

Conclusions: PPD was associated with higher risks of chronic diseases and multimorbidity in women's mid-late life. This finding supports the importance of perinatal and postpartum mental health care, and its role in the prevention of chronic diseases and multimorbidity throughout women's life course.