Association of Paternity Leave with Impaired Father-Infant Bonding: Findings from a Nationwide Online Survey in Japan.

Although the number of fathers taking childcare leave is increasing, the impact of paternity leave on father-infant bonding remains to be fully investigated. This study aimed to assess the association between paternity leave and father-infant bonding among fathers with children under two years old. A cross-sectional study was performed using data from the Japan COVID-19 and Society Internet Survey study, a nationwide online survey conducted between July and August 2021 (N = 1194). Father-infant bonding was assessed by the Japanese version of the Mother-Infant Bonding Scale (MIBS-J), which comprised two subscales (lack of affection (LA), and anger and rejection (AR)), with a higher score denoting poor bonding. Four hundred (33.5%) fathers self-reported taking childcare leave. Paternity leave was associated with higher total MIBS-J score and AR score after adjusting for covariates (coefficient 0.51; 95% confidence interval (CI) 0.06-0.96, coefficient 0.26; 95% CI 0.03-0.49, respectively), but not with LA score (coefficient 0.10; 95% CI -0.13-0.34). There was no trend in the association between paternity leave and total MIBS-J score by children's age group ( for trend = 0.98). Paternity leave was associated with impaired bonding, especially with increased anger and rejection, among fathers with children under two years of age.