[Review on the influence of paternal involvement in childcare on mothers, children, and fathers].

Objectives　Recently, paternal involvement in childcare has been gaining public attention in Japan. However, studies on the influences of active paternal involvement remain scarce. This study aimed to review the findings on the influence of paternal involvement in childcare on mothers, children, and fathers themselves from studies conducted in Japan and published mainly after 2010. Additionally, we examined methodological issues that need to be addressed when researchers conduct studies on paternal involvement in the future.Methods　We reviewed 26 journal articles (22 in Japanese and 4 in English) from four databases: "Igaku Chuo Zasshi Web (Japana Centra Revuo Medicina History and Activities)," JSTPlus, JMEDPlus, and PubMed with conditions such as studies conducted in Japan, families with young children, and questionnaire-based quantitative studies. We described respondents (mothers, fathers, or both) and assessed paternal involvement in childcare, outcomes, and findings.Results　We reviewed studies on paternal involvement in childcare published in Japanese after 2010 and English after 2000 and observed two trends across the studies. The first was that if mothers acknowledge active paternal involvement in childcare, mothers' parenting stress seemed to be lower, and they seemed to be happier. Moreover, for children's health and development, active paternal involvement seemed to be associated with positive results, such as prevention of unintentional injuries and obesity. However, in the second trend, we observed that active paternal involvement, assessed by the fathers themselves, were often not associated with lower parenting stress among mothers. We also could not observe a consistent trend on the findings related to the influences on fathers, due to the limited number of studies. We observed that assessment of paternal involvement in childcare was inconsistent across studies included in this review.Conclusion　With more social pressure for fathers to be actively involved in childcare, public interest for the influence would be heightened. For future studies, better ways of assessing the quantity and content of paternal involvement in childcare need to be discussed.