Paternal involvement in infant care and developmental milestone outcomes at age 3 years: the Japan Environment and Children’s Study (JECS)

Background: In developed countries, the time fathers spend on childcare has increased steadily in recent decades. However, studies on the relationship between paternal care and child outcomes remain scarce. Thus, we examined the association between paternal involvement in childcare and children’s developmental outcomes. Methods: We used Japan’s largest birth cohort data, the Japan Environment and Children’s Study, to examine the relationship between paternal involvement in childcare at the child’s age of 6 months and developmental milestone outcomes at the child’s age of 3 years (n = 28,050). Developmental delays were assessed with Ages and Stages Questionnaire. Potential mediation by maternal parenting stress at the child’s age of 1.5 years was also examined. We used log-binomial regression analyses to estimate risk ratios. Results: Fathers’ high involvement in childcare was associated with a lower risk of developmental delay in gross-motor, fine-motor, problem solving, and personal-social domains compared with low involvement, adjusting for potential confounders. For example, the risk ratio with 95% confidence intervals was 0.76 [0.67, 0.86] for the gross-motor domain. We also observed that the associations were partially mediated by maternal parenting stress. Conclusions: Fathers’ active involvement in childcare during infancy may promote young children’s development, partially by reducing maternal parenting stress. Impact: Using Japan’s largest birth cohort data (Japan Environment and Children’s Study), we showed that paternal involvement in infant care might benefit young children’s development. Fathers’ active involvement in infant care was associated with a lower risk of developmental delays in gross-motor, fine-motor, problem solving, and personal-social domains. Maternal parenting stress may mediate the association between paternal involvement in infant care and child development outcomes at 3 years.