Maternal Self-Efficacy Prolongs, Postpartum Depression Mediates and Social Support Moderates Exclusive Breastfeeding, A prospective Cohort Study

Background: The health benefits of exclusive breastfeeding (EBF) are well established; however, adherence to recommended durations remains suboptimal. This study investigates how maternal breastfeeding self-efficacy (SE), postpartum depressive symptoms, and perceived social support interact to influence EBF duration, providing evidence to guide comprehensive interventions. Methods: This prospective cohort study included 312 postpartum women and divided them into tertiles based on their scores on the Breastfeeding Self-Efficacy Scale (BSES): low (n = 83), moderate (n = 122), and high (n = 107). EBF duration was analyzed using Kaplan–Meier survival curves and Cox proportional hazards regression models. Postpartum depression, measured by the Edinburgh Postnatal Depression Scale (EPDS), was evaluated as a mediator using bootstrap mediation analysis, while perceived social support, assessed by the Personal and Social Performance Scale (PSP), was examined as a moderator through interaction analysis. Results: Median EBF duration was 5.6 months in the low SE group, 5.8 months in the moderate SE group, and was not reached (>6 months) in the high SE group (log-rank p < 0.001). When BSES was modeled categorically, higher breastfeeding self-efficacy was associated with a reduced hazard of discontinuing EBF (high tertile vs. low tertile: hazard ratio [HR] = 0.55, 95% confidence interval [CI]: 0.39–0.78, p = 0.001). Mediation analysis indicated a significant indirect effect of SE on EBF duration through EPDS (indirect effect: –0.18, 95% CI: –0.24 to –0.12), accounting for approximately 40% of the total association between SE and breastfeeding duration. The interaction between BSES and Postpartum Social Support Scale (PSP) was statistically significant (HR for interaction = 0.97, 95% CI: 0.95–0.99, p = 0.030). Stratified analyses showed that the protective association between higher BSES and sustained EBF was strongest among women reporting higher perceived social support. Conclusions: Maternal SE is associated with prolonged EBF, partly through its association with reduced postpartum depressive symptoms. Perceived social support independently promotes EBF persistence and strengthens the beneficial association between SE and breastfeeding duration. Integrated interventions that foster maternal confidence, identify and manage postpartum mood disturbances, and mobilize social support networks are recommended.