Importance  Flexible parental leave schemes can help families balance work, childcare, and postpartum treatment, including treatment for mental health. In Sweden, both parents are eligible to use parental leave simultaneously in the first year after birth; however, the consequences for postpartum mental health care uptake remain underinvestigated.

Objective  To examine the association between parents’ use of simultaneous parental leave and their use of postpartum mental health care in Sweden.

Design, Setting, and Participants  This cohort study obtained baseline data from national registries in Sweden, including live births of singleton offspring between January 1, 2014, to December 31, 2015, and simultaneous parental leave use (any vs none) in the 12 months after birth. The population-based sample was composed of parental dyads (mothers and fathers) who were eligible for simultaneous parental leave and were followed up from January 1, 2015, to December 31, 2016. Statistical analyses were conducted between December 15, 2023, and August 14, 2024.

Exposure  Simultaneous parental leave use up to 12 months post partum.

Main Outcomes and Measures  Total population register data were used to identify maternal and paternal outpatient care visits for mental health (substance use disorder [SUD], mood or affective disorders, and stress-related disorders) and psychotropic prescription dispensations (antidepressants and anxiolytics) during the first postpartum year. Logistic regression was applied to estimate the odds of these outcomes by simultaneous parental leave use, controlling for parents’ age, sociodemographic characteristics, and prebirth mental health care use. Robustness analyses using propensity score matching were performed.

Results  The sample comprised 207 283 parental dyads, of whom 153 342 (74.0%) did not use simultaneous parental leave in the first postpartum year and 53 941 (26.0%) did. Among those who used simultaneous parental leave, the mean (SE) age at childbirth was 29.63 (0.02) years for mothers and 32.80 (0.03) years for fathers. Compared with mothers who did not use parental leave simultaneously with their partners, mothers who did were more likely to receive antidepressant prescriptions in the first postpartum year (odds ratio [OR], 1.07; 95% CI, 1.02-1.11). Fathers who used simultaneous parental leave vs those who did not had increased odds of SUD-related outpatient care visits (OR, 1.10; 95% CI, 1.02-1.20). Longer simultaneous parental leave was associated with greater odds of mental health care use for both parents, and earlier leave was associated with greater odds of health care use by mothers. Findings for mothers, but not fathers, remained significant in robustness analyses using propensity score matching.

Conclusions and Relevance  This cohort study found that simultaneous parental leave use was associated with greater health care uptake for postpartum mental health conditions in both mothers and fathers. This finding supports the need to consider the benefits of generous family policies as well as the risks of structural obstacles to postpartum mental health care access across the world.