Postpartum depression among women in South Korea during COVID-19 pandemic: a nationwide study

Pregnancy and childbirth are periods of substantial psychological and hormonal change, during which women may be vulnerable to depression. However, changes in clinically diagnosed postpartum depression (PPD) during the coronavirus disease 2019 (COVID-19) pandemic remain incompletely understood. This study aimed to examine temporal trends in diagnosed PPD rates in South Korea and to evaluate whether the onset of the COVID-19 pandemic altered the pre-existing trajectory of clinically diagnosed PPD. This observational cohort study used the data collected from the Korean National Health Insurance Service database for the period between January 2015 and December 2021. Diagnosed PPD was identified using the diagnostic codes in ICD-10 (ICD-10 diagnostic codes: F32 and F33) recorded within three months postpartum. We identified 1,877,619 women who delivered between January 2015 and December 2021. We classified the period of delivery between January 2015 and December 2019, and January 2020 and December 2021 as the pre-pandemic and pandemic periods, respectively. Four-week interval-specific diagnosed PPD rates were calculated as the number of diagnosed PPD cases divided by the number of deliveries in each interval and expressed as percentages. Interrupted time series analysis of diagnosed PPD rates was performed to evaluate changes in the level and trend of diagnosed PPD after the onset of the COVID-19 pandemic. Of the 1,877,619 women included in the study, 1,447,992 delivered during the pre-pandemic period and 429,627 delivered during the pandemic period. The overall rate of diagnosed PPD within 3 months postpartum was 0.37% in the pre-pandemic period and 0.43% during the pandemic period. Women diagnosed with PPD were generally older and had higher rates of preterm birth, twin pregnancy, chronic hypertension, hypertensive disorders of pregnancy, and placenta previa than those without diagnosed PPD. In the AR(1)-adjusted interrupted time series analysis, the diagnosed PPD rate showed an increasing trend before the COVID-19 pandemic, with an estimated increase of 0.0104 percentage points per four-week interval (95% CI, 0.0069 to 0.0138; p < .001). At the onset of the COVID-19 pandemic, the diagnosed PPD rate showed an immediate absolute decrease of 0.2562 percentage points (95% CI, -0.4644 to -0.0481; p < .05). The slope change after pandemic onset was not significant (0.0001 percentage points per four-week interval; 95% CI, -0.0158 to 0.0159), indicating that the pandemic-period trend did not differ significantly from the pre-pandemic trend. Although there was an immediate decline in the diagnosed PPD rate following the onset of the COVID-19 pandemic, the overall long-term increasing trend of diagnosed PPD remained unchanged. Clinical trial number: not applicable.