[Association between father's involvement with his wife/partner during pregnancy and father-to-infant bonding failure].

Objectives　Bonding failure is lack of parental emotional relationship between a parent and their infant. This study aims to investigate the association between father's involvements with their partner during pregnancy.Methods　A total of 1,957 partners of pregnant women who had visited three maternity hospitals in Sapporo from May 2016 to December 2017 were included in the study. Self-administered questionnaires were distributed to participants at 2,435 weeks gestation and at 6-8 weeks postpartum. The fathers who responded to both the questionnaires were included in the analysis. The participants' relationship with their partners during pregnancy was rated using two questions- whether they help their partner with personal care and household chores, and whether they consult with their partner. Answers for both questions were given on a scale of 0 to 4. A total score of 6-8 points was defined as a high-score group, 3-5 points as a mid-score group, and 0-2 points as a low-score group. Bonding failure was evaluated using the Japanese version of the Mother-Infant Bonding Scale (MIBS-J). The cut-off value was the score that included the top 10% with the highest degree of bonding disorder. A logistic regression was used to analyse the association between involvement with a partner during pregnancy and bonding failure. The confounding variables were father's age, household income, father's average working hours, previous pregnancy, history of abortion/a stillbirth/the death of the child, and partner's prepartum depression during pregnancy.Results　391 fathers responded to the initial questionnaire, and 86.4% of them filled out the second questionnaire up to 2 months postpartum, 10.6% up to 3 months, 2.5% up to 4 months, and 1.0% up to 5 months. Of these, 375 were included, excluding those with missing questionnaire items. 255 fathers were in the high score group of the involvement with partner during pregnancy, 48 had bonding failure, 35 had LA, and 17 had AR. The OR based on the high score group of involvement with partner during pregnancy for bonding failure was 4.81 (1.88-12.33) for mid-score group, and 6.89 (1.40-33.93) for low-score group, and for LA, 2.21 (0.97-5.04) for mid-score group, and 6.40 (1.54-26.68) for low-score group; however, AR showed no respectively significant association (trend P 0.0005, 0.0053, 0.6859).Conclusions　The results suggest that a father's unfavorable involvement with his partner affects the bonding with their infant. This suggests that involvement with a partner during pregnancy is an important factor in preventing bonding failure in fathers.