A Japanese version of Mother-to-Infant Bonding Scale: factor structure, longitudinal changes and links with maternal mood during the early postnatal period in Japanese mothers

The objectives of this study were (1) to develop a Japanese version of Mother-to- Infant Bonding Scale Japanese version (MIBS-J) based on Kumar's Mother Infant Bonding Questionnaire that could be used to screen the general population for problems in the mother's feelings towards her new baby and to validate it for clinical use and (2) to examine the factor structure of the items and create subscales of the questionnaire for the Japanese version. The MIBS-J is a simple self-report questionnaire designed to detect the problems in a mother's feelings towards her newborn baby. Participants (n = 554) were recruited at an outpatient clinic of a maternity hospital in a community after 30-weeks gestation. MIBS-J and the Edinburgh Postnatal Depression Scale (EPDS) were administered on the fifth day at the maternity ward and mailed at 1 and 4 months postnatally. Exploratory factor analysis and confirmatory factor analysis demonstrated a two-factor structure out of eight items: lack of affection (LA) and anger/rejection (AR). Chronbach's alpha coefficients were 0.71 and 0.57, respectively. The LA and AR scores had strong correlations across postnatal times. The mothers with higher (worse) AR scores on the MIBS-J at any of the three periods had higher scores on the EPDS. MIBS-J demonstrated acceptable reliability and reasonable construct validity in this Japanese sample.