Psychiatric consequences of a father's leave policy by nativity: a quasi-experimental study in Sweden.

Background: Parental leave use has been found to promote maternal and child health, with limited evidence of mental health impacts on fathers. How these effects vary for minority populations with poorer mental health and lower leave uptake, such as migrants, remains under-investigated. This study assessed the effects of a Swedish policy to encourage fathers' leave, the 1995 , on Swedish-born and migrant fathers' psychiatric hospitalisations.

Methods: We conducted an interrupted time series analysis using Swedish total population register data for first-time fathers of children born before (1992-1994) and after (1995-1997) the reform (n=198 589). Swedish-born and migrant fathers' 3-year psychiatric hospitalisation rates were modelled using segmented negative binomial regression, adjusting for seasonality and autocorrelation, with stratified analyses by region of origin, duration of residence, and partners' nativity.

Results: From immediately pre-reform to post-reform, the proportion of fathers using parental leave increased from 63.6% to 86.4% of native-born and 37.1% to 51.2% of migrants. Swedish-born fathers exhibited no changes in psychiatric hospitalisation rates post-reform, whereas migrants showed 36% decreased rates (incidence rate ratio (IRR) 0.64, 95% CI 0.47 to 0.86). Migrants from regions not predominantly consisting of Organisation for Economic Cooperation and Development countries (IRR 0.50, 95% CI 0.19 to 1.33), and those with migrant partners (IRR 0.23, 95% CI 0.14 to 0.38), experienced the greatest decreases in psychiatric hospitalisation rates.

Conclusion: The findings of this study suggest that policies oriented towards promoting father's use of parental leave may help to reduce native-migrant health inequalities, with broader benefits for family well-being and child development.