Kangaroo mother care and maternal bonding 1 year after childbirth: a nationwide birth cohort—the Japan environment and children’s cohort study

To prevent bonding disorder, support should be provided both immediately after childbirth and in the long term. This study focuses on the prevention of bonding disorder and aimed to clarify the effect of early mother–infant contact on mother-to-infant bonding 1 year after childbirth. The participants were 81,634 mothers involved in an ongoing nationwide birth cohort study called the Japan Environment and Children’s Study. Mother-to-infant bonding was measured using the Mother-to-Infant Bonding Scale, Japanese version (MIBS-J). Mother–infant contact after childbirth was classified as “no contact”, “clothed or swaddled contact”, and “skin-to-skin contact”. Mother–infant bonding disorder was identified based on an MIBS-J score of ≥ 5, and analyses were also performed based on the sub-scores for “Lack of Affection” and “Anger and Rejection”. A generalized linear mixed model analysis was used to derive adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for cases of bonding disorder and subscale scores according to mother–infant contact, with no contact as the reference group and while controlling for potential confounders. One year after childbirth, the clothed or swaddled contact group (AOR 0.93, 95% CI 0.87–0.99) and the skin-to-skin contact group (AOR 0.85, 95% CI 0.81–0.90) had a significantly lower odds of bonding disorder compared with the no contact group. By subscale, the odds of bonding disorder on the Lack of Affection subscale was lower in the skin-to-skin contact group (AOR 0.91, 95% CI 0.89–0.93) than in the no contact group. For the Anger and Rejection subscale, the odds of bonding disorder was lower in the clothed or swaddled contact group (AOR 0.94, 95% CI 0.92–0.96) and in the skin-to-skin contact group (AOR 0.92, 95% CI 0.91–0.94) than in the no contact group. Early skin-to-skin contact between mother and child immediately after childbirth is associated with a reduced likelihood of long-term bonding disorder in mothers.