Factor structure and measurement invariance of the Japanese version of the Mother-to-Infant Bonding Scale during the perinatal period: a longitudinal study of Japanese women

BACKGROUND: The Japanese version of the Mother-to-Infant Bonding Scale, a 10-item self-administered questionnaire, was developed as a screening instrument for bonding disorder. Our study aimed to examine the configural and measurement invariance of the factor structure of the MIBSJ from a 3-wave prospective cohort study. METHODS: Postpartum mothers (N.446) were surveyed at 1, 3, and 6 months after postpartum. All participants were randomly divided into two subgroups, one for exploratory factor analysis (EFA) and another for confirmatory factor analysis (CFA). Measurement invariance of the best model was tested using the entire sample across the three observation periods. RESULTS: The number of women who returned the questionnaires was 446, 412, and 399 at the three measurement time points, respectively. The present study demonstrated that the 3-item 1-factor model fit the data better than those derived from our EFA. The 3-item 1-factor model was stable across the perinatal period at the level of metric invariance. CONCLUSIONS: The present study encourages clinicians to use the 3-item MIBSJ rather than the full 10-item version in the first six postpartum months. The 3-item version is easier to use and more stable across the perinatal period.