Objective: To examine the association of breastfeeding with maternal sensitive responsiveness and infant-mother attachment security and disorganization.
Methods: We included 675 participants of a prospective cohort study. Questionnaires about breastfeeding practices were administered at 2 and 6 months postpartum. At 14 months, maternal sensitive responsiveness was assessed in a 13-minute laboratory procedure using Ainsworth's sensitivity scales, and attachment quality was assessed with the Strange Situation Procedure. Mothers were genotyped for oxytocin receptor genes OXTR rs53576 and OXTR rs2254298. Linear regressions and analyses of covariance adjusted for various background variables were conducted. We tested for mediation and moderation by maternal sensitive responsiveness and maternal oxytocin receptor genotype.
Results: Continuous analyses showed that longer duration of breastfeeding was associated with more maternal sensitive responsiveness (B = 0.11, 95% confidence interval [CI] 0.02; 0.20, p < .05), more attachment security (B = 0.24, 95% CI = 0.02; 0.46, p < .05), and less attachment disorganization (B = -0.20, 95% CI -0.36; -0.03, p < .05). Duration of breastfeeding was not related to the risk of insecure-avoidant or insecure-resistant versus secure attachment classification, but longer duration of breastfeeding predicted a lower risk of disorganized versus secure attachment classification (n = 151; odds ratio [OR] = 0.81, 95% CI 0.66 to 0.99, p = .04). Maternal sensitive responsiveness did not mediate the associations, and maternal oxytocin receptor genotype was not a significant moderator.
Conclusions: Although duration of breastfeeding was not associated with differences in infant-mother attachment classifications, we found subtle positive associations between duration of breastfeeding and sensitive responsiveness, attachment security, and disorganization.