Background <p>Mother–infant bonding begins during pregnancy, and a strong bond is crucial for a child's physical and psychological development. The development of this bond is influenced by various factors, including the mother’s psychosocial wellbeing and the support she receives during pregnancy and after childbirth. However, few longitudinal studies have examined this topic, and previous results of cross-sectional studies have been somewhat contradictory. Our objective was to investigate the development of postnatal maternal bonding and to identify the most significant pre- and postnatal psychosocial risk factors that influence maternal bonding at eight months postpartum.</p> Methods <p>This longitudinal study examined 1298 mothers. Psychiatric symptoms and social risk factors were assessed using standardized self-report questionnaires. The change in bonding from three months to eight months was analyzed using repeated measures ANOVA. The maternal psychosocial factors associated with bonding at eight months were examined using logistic regression analysis.</p> Results <p>We found that maternal bonding improved among all the mothers between three and eight months postpartum. However, mothers who experienced psychiatric symptoms or social problems exhibited weaker bonding at both three and eight months postpartum. The most significant risk factors for bonding issues at eight months were bonding disturbances at three months and a lack of positive expectations regarding the relationship with the unborn baby. Postnatal depression, stress, and anxiety were also linked to an increased risk of bonding disturbances.</p> Conclusion <p>We recommend that healthcare professionals focus on identifying difficulties in mother–infant bonding during the prenatal and perinatal periods. They should also consider psychiatric symptoms when assessing the need for support.</p>