Maternal Bonding Difficulties and Postpartum Depression: A Longitudinal Analysis in a Single- Center Japanese Cohort

Background Maternal bonding difficulties represent an important yet under-recognized aspect of perinatal mental health, influencing both maternal well-being and child development. Although numerous studies have examined postpartum depression (PPD) and bonding impairment, few have investigated their longitudinal relationship within general pediatric settings in Japan. Methods This single-center retrospective cohort study analyzed data from 512 mother–infant dyads who delivered 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. Growth Mixture Modeling (GMM) identified latent trajectories of EPDS and MIBS scores, and multinomial logistic regression examined background factors associated with poor bonding. Results GMM identified five latent classes for MIBS and four for EPDS. A subgroup characterized by persistently worsening bonding difficulties (MIBS Class 2: increased poor bonding) and increasing depressive symptoms (EPDS Class 1: increased depression) was observed. Approximately 70% of mothers in MIBS Class 2 also belonged to EPDS Class 1. Higher EPDS total, anxiety, and anhedonia scores in the early postpartum period predicted elevated MIBS scores at three months. Among background factors, refusal of public health nurse home visits and insufficient opportunities to consult with partners or others were significantly associated with poor bonding trajectories. In contrast, economic hardship and unmarried status were not significant predictors. Conclusions Persistent maternal emotional instability during the early postpartum period worsens bonding difficulties. Incorporating systematic screening with the EPDS and MIBS into pediatric clinical practice, together with empathic listening and early referral to mental health or social support services, may help identify high-risk mothers, and prevent subsequent child maltreatment.