Maternal bonding difficulties and postpartum depression in pediatric clinical practice: a longitudinal study in a Japanese cohort.

Background: Maternal bonding difficulties are an important yet under-recognized aspect of perinatal mental health, influencing both maternal well-being and child development. Although studies have examined postpartum depression and bonding impairment, few have investigated their longitudinal relationship within general pediatric settings in Japan. Methods: This single-center observational study analyzed data from 512 mother-infant dyads following delivery at a general hospital in Fukuoka, Japan. Maternal depressive symptoms and bonding were assessed at five days and one, two, and three months postpartum using the Edinburgh Postnatal Depression Scale (EPDS) and Mother-to-Infant Bonding Scale (MIBS), respectively. Latent growth models were estimated, and the resulting intercept and slope factor scores were subsequently subjected to Gaussian mixture-based clustering to identify trajectory-based subgroups. This analysis was conducted using an exploratory framework. The MIBS trajectory analyses were conducted on a subsample of 77 mothers with complete MIBS data, whereas the EPDS trajectory analyses used full information maximum likelihood-derived factor scores from 512 mothers. Results: In the linear mixed-effects model using all available paired observations, higher EPDS total scores were significantly associated with higher subsequent MIBS scores across the early postpartum period. Exploratory clustering of latent growth model-derived factor scores suggested three MIBS and four EPDS trajectory-based subgroups, characterized by different baseline levels and decreasing or persistent depressive symptom patterns. The EPDS total and subscale scores were also associated with MIBS scores. Because the MIBS trajectory analysis was based on a small, clinically selected, complete-case sample, subgroup-specific findings should be interpreted cautiously. Conclusions: Repeated EPDS and MIBS assessments in pediatric clinical practice may help characterize the associations between postpartum depressive symptoms and maternal bonding difficulties during the early postpartum period. Exploratory trajectory-based analyses suggested heterogeneous bonding-difficulty patterns, including a subgroup with increasing MIBS scores over the first three months postpartum. Further studies are required to determine whether such assessments can improve maternal and child outcomes.