IntroductionThe objective of this study is to investigate the effect of the distribution of a booklet providing information to fathers during their partners' pregnancies on fathers' and mothers' postpartum mental health and quality of life (QOL), as well as on fathers' childcare participation and living situations.Methods and analysisThis randomised controlled trial will comprise 554 couples consisting of pregnant women due to give birth at an obstetric institution in Aichi Prefecture, Japan and their partners. Participants will be recruited during prenatal check-ups in the third trimester, and those who provide written consent will be allocated randomly to an intervention and a control group. The pregnant women's partners allocated to the intervention group will be given a booklet written for men containing information on childbirth and postnatal period. Its content will include matters such as what preparations the partner should make before birth and tips for housework and childcare as well as how to prevent unintentional injury to the baby. The control group will not receive any intervention. A baseline survey in the third trimester and follow-up surveys at 1 and 3 months post partum will be carried out using self-administered questionnaires. The primary outcome is the proportion of new mothers' partners at risk for paternal depression (Edinburgh Postnatal Depression Scale score ≥8). Secondary outcomes include the risk of postnatal depression in new mothers, QOL of new mothers and their partners, partners' knowledge of and engagement in housework and childcare, marital relations and parenting stress on the part of new mothers.Ethics and disseminationThis study has been approved by the Ethical Committee at the National Center for Child Health and Development, Tokyo, Japan. The results of the study will be widely disseminated as peer-reviewed papers and at international conferences, with the aim of improving public health services in Japan.Trial registration numberUMIN000021475; Pre-results.

Background Postpartum paternal depression (PPPD) is under-acknowledged worldwide compared to maternal depression, despite PPPD prevalence being reported to be just as high. Although PPPD has clear health consequences, even on other family members, preventive methods have been under-studied. We investigated the association between an educational intervention and risk of PPPD. Methods We performed a parallel-group, randomized controlled trial in an obstetrics clinic in Japan that included expecting fathers and their pregnant partners at 28-32 weeks gestation. The intervention comprised an educational booklet created for fathers that was distributed during pregnancy. For the primary outcome, Edinburg Postnatal Depression Scale (EPDS) was administered at one and three months post-delivery, and EPDS of 8 or greater was considered at risk for depression. Results In total, the intervention and control groups comprised 286 and 282 couples, respectively. At follow-up, depressive symptoms were observed in 7.2% of fathers in the intervention group and 9.8% in the control group (odds ratio [OR] = 0.71, 95% confidence interval [CI] = 0.36-1.36). Logistic regression in an adjusted analysis showed a reduced, but non-significant risk of PPPD (odds ratio=0.61, 95% confidence interval=0.31-1.20). Conclusions In the first PPPD intervention study of its kind in Japan, our study suggests that distributing the educational booklet to fathers may be helpful in general, but may not be enough to significantly influence the risk of a major condition like PPPD. Key messages A more personalized preventive approach beyond the simple administration of a booklet may be necessary to significantly impact PPPD occurrences.