Time trends in incidence of postpartum depression and depression in women of reproductive age.

BACKGROUND

Little is known about the time trends of postpartum depression (PPD) and whether they differ from time trends of depression among women in general.

METHODS

Using Danish health registers, we identified a postpartum population from all women who had a liveborn child from 2000-2022. We sampled a background population by matching five women for each delivery on age and date of childbirth. Depression and PPD were measured as incident depression diagnosis or redeemed antidepressant prescription within 180 days from childbirth/matching. We described incidence rates from 2000-2022 using Poisson regression with a restricted cubic spline.

RESULTS

The study population included 1,133,947 postpartum women (669,101 unique), matched to 5,669,735 women (1,165,505 unique). Overall IR per 10,000 person-years of diagnoses was 34.3 (95% CI: 32.8-35.9) for PPD and 18.9 (95% CI: 18.3-19.4) for depression. Both IRs increased similarly over time in the main analyses, but more pronounced for PPD in primiparous and older mothers. Correspondingly, IR for prescriptions was 135.7 (95% CI: 132.7-138.8) for PPD and 209.8 (95% CI: 208.1-211.5) for depression, and both groups had fluctuating time trends.

LIMITATIONS

Depression measures were based on women who actively sought and received treatment, expectedly underestimating true disease incidence.

CONCLUSIONS

Incidence rates of PPD and depression diagnoses increased over time, especially for PPD among primiparous and older mothers. These findings could suggest either increased vulnerability or increased awareness and detection over time in these groups. Fluctuating trends overserved from prescriptions could likely be driven by external factors and not a reflection of disease trends.