This study investigated whether the nurturing hypothesis—that breastfeeding serves as a proxy for family socioeconomic characteristics and parenting behaviors—accounts for the association of breastfeeding with children’s academic abilities. Data used were from the Child Development Supplement of the Panel Study of Income Dynamics, which followed up a cohort of 3,563 children ages 0–12 in 1997. Structural equation modelling simultaneously regressed outcome variables, including three test scores of academic ability and two subscales of behaviour problems, on the presence and duration of breastfeeding, family socioeconomic characteristics, parenting behaviours, and covariates. Breastfeeding was strongly related to all three tests scores but had no relationships with behavior problems. The adjusted mean differences in the Letter-Word Identification, Passage Comprehension, and Applied Problems test scores between breastfed and nonbreastfed children were 5.14 [95% confidence interval (CI): 3.14, 7.14], 3.46 (95% CI: 1.67, 5.26), and 4.24 (95% CI: 2.43, 6.04), respectively. Both socioeconomic characteristics and parenting behaviors were related to higher academic test scores and were associated with a lower prevalence of externalising and internalising behavior problems. The associations of breastfeeding with behavior problems are divergent from those of socioeconomic characteristics and parenting behaviors. The divergence suggests that breastfeeding may not be a proxy of socioeconomic characteristics and parenting behaviors, as proposed by the nurturing hypothesis. The mechanism of breastfeeding benefits is likely to be different from those by which family socioeconomic background and parenting practices exert their effects. Greater clarity in understanding the mechanisms behind breastfeeding benefits will facilitate the development of policies and programs that maximise breastfeeding’s impact.
Huang, J., Vaughn, M. G., & Kremer, K. P. (2015). Breastfeeding and child development outcomes: An investigation of the nurturing hypothesis. Maternal and Child Nutrition. Advance online publication. doi:10.1111/mcn.12200