Maternal personality and postnatal bonding disorder in Japan: the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study

Background: Despite much knowledge of the effects of maternal psychopathology on bonding, the effects of personality have received less attention. We aimed to examine the association between maternal personality and postnatal bonding disorder. Methods: We analyzed data from 15,654 women who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Personality was assessed in middle pregnancy using the short-form Eysenck Personality Questionnaire-Revised, with the score for each subscale categorized into four levels. Bonding disorder was defined as the Mother-to-Infant Bonding Scale score of ≥5 one month after delivery. Multiple logistic regression analyses were conducted to examine the association between personality and bonding disorder after adjusting for age, education, parity, feelings towards pregnancy, social isolation, as well as the Edinburgh Postpartum Depression Scale (EPDS) score. Results: Higher extraversion was associated with a decreased risk of bonding disorder (p for trend <0.001). Higher neuroticism was associated with an increased risk of bonding disorder (p for trend <0.001), and this association disappeared after further adjustment for EPDS score (p for trend 0.39). No association between psychoticism and bonding disorder was observed (p for trend 0.83), and the association appeared after further adjustment for EPDS score (p for trend 0.0017). Higher lie was associated with a decreased risk of bonding disorder (p for trend <0.001). Limitations: Maternal personality and bonding were self-reported. Conclusions: Lower extraversion, higher psychoticism, and lower lie were associated with bonding disorder. The association between higher neuroticism and bonding disorder was explained by postnatal depressive symptoms.