Difficult temperament, breastfeeding, and their mutual prospective effects: the Norwegian Mother and Child Cohort Study.

Objective: (1) To examine the extent to which difficult temperament and breastfeeding are associated at child age 6 and 18 months. (2) To examine longitudinally whether breastfeeding has an influence on temperament development or whether difficult temperament has an influence on continued breastfeeding. Method: This prospective study is part of the Norwegian Mother and Child Cohort Study, which targets all women giving birth in Norway; the present sample comprises 30,466 children. Mothers reported on child difficult temperament at child age 6 and 18 months and on breastfeeding from 0 to 6 months and from 6 to 12-14 months. Prospective associations between breastfeeding and difficult temperament were examined using structural equation modeling, with comparison of cross-lagged pathways. All analyses were adjusted for background variables that are relevant for breastfeeding. Results: At 6 months, children with more difficult temperament were significantly less likely to have been "fully" breastfed (exclusively and predominantly breastfed) for the recommended period of 6 months (unadjusted point-biserial correlation r(pb) = -.15; adjusted r(pb) = -.11). At 12 to 14 months, there was no longer an association between difficult temperament and (continued) breastfeeding after adjusting for background variables, temperament, and breastfeeding at 6 months. The cross-lagged analyses of the longitudinal pathways yielded negligible effects of difficult temperament on later breastfeeding and of breastfeeding on later temperament. Conclusion: Difficult temperament and reduced breastfeeding seem to be associated only during the first half-year of the child's life. After that, we found no evidence of codevelopment between difficult temperament and breastfeeding.