The Feasibility, Acceptability, and Preliminary Effects of a Prenatal Preventive Intervention Program for Coparenting: A Pilot Study in Japan

Background/Objectives: The coparenting relationship newly formed during the transition to parenthood is a relational system focused on parenting. This study was positioned as an exploratory survey, because it evaluated a preventive intervention program developed for couples expecting their first child with the goal of promoting coparenting, focusing solely on the prenatal period. This self-guided program was primarily composed of brief video for viewing and homework that were provided to couples through the pregnant women. The primary objective of this study was to evaluate the feasibility and acceptability of the intervention, and the secondary objective was to explore its preliminary effects; all assessments were based on data collected from pregnant women. Methods: This was a pilot study employing a mixed-methods approach with intervention and comparison groups. The evaluation utilized self-reported data collected at 22–27 weeks’ and 36 weeks’ gestation, along with data gathered through responses to questions in Microsoft Forms and semi-structured interviews, particularly in the intervention group. Ultimately, 20 couples in each group were included in the analysis. Results: Approximately 80% of couples in both groups agreed to participate, enhancing the feasibility of the intervention that included approaches to couples through pregnant women. The intervention completion rate was high (87%), and many women found the program acceptable. Analysis of covariance for between-group comparisons revealed no significant differences in relationship satisfaction (p = 0.267) or prenatal coparenting (p = 0.239). Conclusions: This program was recognized as feasible and acceptable, but its preliminary effects during pregnancy were not confirmed. Randomizing participants and including outcome assessments after childbirth in future studies could contribute to enhancing the potential for beneficial interventions.