Spot the Red Herring: Breastfeeding, Fruitpurée, and Infant Autonomic Functioning—The Generation R Study

Abstract

Several studies have suggested that breastfeeding is related to infant autonomic functioning. The authors investigated whether this is a causal relation. In all, 444 mothers reported breastfeeding practices 2 mo postpartum. Infant autonomic functioning was assessed by heart rate variability at age 14 mo, after discontinuation of breastfeeding. The dose-dependent association between breastfeeding and infant autonomic functioning was tested with linear regression models adjusted for multiple confounders. The authors investigated the relation of fruitpurée consumption with infant autonomic functioning. Fruitpurée consumption has similar socioeconomic epiphenomena but is not related via the same causal mechanism to autonomic regulation as breastfeeding. Nonbreastfed infants had high sympathetic modulation [7.87 log (ms)/SD, 95% CI: 7.71-8.02], partially breastfed infants had intermediate sympathetic modulation [7.75 log (ms)/SD, 95% CI: 7.51-7.82], sympathetic modulation of exclusively breastfed infants was low [7.63 log (ms)/SD, 95% CI: 7.50-7.77]. However, this association could be explained by socioeconomic confounders. Furthermore, fruitpurée consumption was similarly associated with reduced infant sympathetic modulation. The association between breastfeeding practices and infant sympathetic modulation was accounted for by socioeconomic and environmental factors. We found a similar association between fruitpurée consumption and autonomic functioning, further suggesting that the association between breastfeeding and infant autonomic functioning is noncausal.