Prenatal anxiety, breastfeeding and child growth and puberty: linking evolutionary models with human cohort studies.

Background: Stress experienced by mothers during pregnancy can have both immediate and long-term effects on child development, potentially mediated by breastfeeding. Aim: Using a UK birth cohort study, we asked how maternal stress relates to breastfeeding and consequences for growth and puberty onset. Subjects and methods: We analysed data from the Avon Longitudinal Study of Parents and Children, collected via questionnaires and clinic visits (N: 698-8,506). We used reports of prenatal anxiety, breastfeeding, early growth and age at menarche or first voice change. Confounding by maternal age, parity, smoking, education and body mass index (BMI) was considered. Results: Mothers with higher levels of reported anxiety were less likely to breastfeed (Odds ratio (OR): 0.83, 95% confidence interval (CI): 0.71, 0.97). Breastfed infants had slower growth before weaning, although growth differences were unclear thereafter. Being breastfed for more than six months was associated with later puberty onset in females (2.76 months later than non-breastfed; CI: 0.9, 4.63), although the association was attenuated by confounders and BMI (1.51 months, CI: -0.38, 3.40). No association between breastfeeding and puberty onset in males was found. Conclusion: Our studies fit results shown previously, and we consider these in light of evolutionary life history theory while discussing key challenges in such an approach.