Identification of Bonding Difficulties in the Peripartum Period Using the Mother-to-Infant Bonding Scale-Japanese Version and Its Tentative Cutoff Points

PURPOSE: Identification of pregnant women with bonding difficulties is important to provide early intervention. However, few studies have examined the utility of self-report questionnaires that assess mother–infant bonding as screening tools for bonding difficulties. This longitudinal study aimed to identify pregnant women with bonding difficulties using the Japanese version of the Mother-to-Infant Bonding Scale (MIBS-J) and to estimate its optimal cutoff points in the peripartum period. PATIENTS AND METHODS: A total of 1301 pregnant women completed the MIBS-J and Hospital Anxiety and Depression Scale (HADS) at three time points: first trimester (T1; approximately 12–15 weeks gestation), third trimester (T2; approximately 30–34 weeks gestation), and postpartum (T3; approximately 4 weeks postpartum). A two-step cluster analysis was conducted to classify pregnant women based on their MIBS-J subscale scores at the three time points. Based on the cluster analysis results, receiver operating characteristic curve analysis was performed to estimate the optimal cutoff scores for the MIBS-J total score at each time point. RESULTS: The two-step cluster analysis produced two clusters: Cluster 1 (n = 824) and Cluster 2 (n = 477). Both the MIBS-J and HADS scores were significantly higher in Cluster 2 than in Cluster 1 at all time points. The MIBS-J tentative cutoff points were 3/4, 3/4, and 2/3 at T1, T2, and T3, respectively. CONCLUSION: We identified two distinct groups across the perinatal period: pregnant women with bonding difficulties and pregnant women with normal bonding. Our findings suggest the usefulness of the MIBS-J as a screening tool to identify bonding difficulties during pregnancy.