Peripartum Magnesium Sulfate and Post-Delivery Depression: A Nationwide Cohort Study With 13-Year Follow-Up

Although its potential antidepressant effects have been suggested, evidence on long-term outcomes for post-delivery depression remains limited. We evaluated whether peripartum intravenous magnesium sulfate (MgSO₄) is associated with a reduced risk of postpartum depression (PPD) within 12 months and its long-term trajectory over 13 years.

This nationwide retrospective cohort study included all women in South Korea who delivered between 2010 and 2014, excluding those with prior depression. Exposure was defined as intravenous MgSO₄ administration during delivery hospitalization. Propensity score (PS) matching (1:5) was used to balance baseline characteristics. We employed Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for both 12-month PPD and long-term depression (up to 13 years).

Among 1,583,253 eligible mothers, 9,756 (0.6%) received MgSO₄. In the PS-matched cohort (9,682 exposed; 35,140 unexposed), there was no significant association between MgSO₄ and the primary outcome of 12-month PPD (HR, 1.11; 95% CI, 0.97-1.26; p=0.114). Similarly, the risk of long-term post-delivery depression showed no significant difference (HR, 1.02; 95% CI, 0.97-1.07; p=0.388). These findings were consistent in the dose-response analysis for 12-month PPD (HR, 1.10 per 10 g increase; 95% CI, 0.96- 1.24; p=0.144) and in subgroup analyses stratified by preeclampsia status.

Peripartum MgSO₄ exposure was not associated with a reduced risk of either 12-month PPD or long-term post-delivery depression. Despite its biological plausibility, routine obstetric use of MgSO₄ does not appear to confer preventive mental health benefits for mothers in the general obstetric population.