# Risk factors for treatment resistance among women with postpartum depression in a nationwide study

## TL;DR

This study identifies risk factors for treatment-resistant postpartum depression in women using nationwide data from Sweden.

## Contribution

The study provides the first nationwide assessment of treatment resistance in postpartum depression and its associated risk factors.

## Key findings

- Six percent of women with postpartum depression experienced treatment resistance within one year.
- Lower income, education, and pre-existing conditions were linked to higher treatment resistance risk.
- Having two births or a prior premenstrual disorder was associated with lower treatment resistance risk.

## Abstract

The occurrence of treatment resistance in women with postpartum depression (PPD) and risk factors for treatment resistance remain less studied. This study aimed to determine the rate of treatment resistance and the associated risk factors among women with PPD in a nationwide setting. Here we conducted a nationwide register-based cohort study of 58,618 patients with a first-ever PPD during 2006–2021 in Sweden. Information on demographics, pregnancy characteristics, pre-existing physical and psychiatric conditions and treatment was retrieved from Swedish national registers. The outcome was treatment-resistant PPD (TRPPD) within 1 year following PPD diagnosis. Associations between potential risk factors and TRPPD were assessed using multivariable Poisson regression. Among the 58,618 patients with PPD, 3,522 (6.0%) met the criteria for TRPPD during 1 year after PPD diagnosis. Lower educational level, lower household income, being non-cohabiting, smoking in early pregnancy, delivery by cesarean section, pre-existing physical conditions and pre-existing psychiatric disorders were significantly associated with a higher risk of TRPPD. In addition, patients with two births (versus primiparity) or with a prior premenstrual disorder had a lower risk of TRPPD. Treatment resistance in patients with PPD is common and is notably associated with specific demographic and clinical profiles. These findings may provide grounds for practical risk assessment at PPD diagnosis and highlight the need for personalized management strategies.

Chen et al. assessed the prevalence and risk factors for treatment-resistant postpartum depression using nationwide data from the Swedish National Medical Birth Register.