Age at Weaning and Infant Growth: Primary Analysis and Systematic Review.
OBJECTIVE: To test whether earlier age at weaning (age 3-6 months) may promote faster growth during infancy. STUDY DESIGN: Weaning at age 3.0-7.0 months was reported by 571 mothers of term singletons in a prospective birth cohort study conducted in Cambridge, UK. Infant weight and length were measured at birth and at age 3 months and 12 months. Anthropometric values were transformed into age- and sex-adjusted z-scores. Three linear regression models were performed, including adjustment for confounders in a stepwise manner. Measurements at age 3 months, before weaning, were used to consider reverse causality. RESULTS: Almost three-quarters (72.9%) of infants were weaned before age 6 months. Age at weaning of 3.0-7.0 months was inversely associated with weight and length (but not with body mass index) at 12 months (both P ≤ .01, adjusted for maternal and demographic factors). These associations were attenuated after adjustment for type of milk feeding and weight or length at age 3 months (before weaning). Rapid weight gain between 0 and 3 months predicted subsequent earlier age at weaning (P = .01). Our systematic review identified 2 trials, both reporting null effects of age at weaning on growth, and 15 observational studies, with 10 reporting an inverse association between age at weaning and infant growth and 4 reporting evidence of reverse causality. CONCLUSION: In high-income countries, weaning between 3 and 6 months appears to have a neutral effect on infant growth. Inverse associations are likely related to reverse causality.
Medical Research Council (G1001995)
National Institute for Health Research (NIHR) (via West Anglia Comprehensive Local Research Network (CLRN)) (11822)
National Institute for Health Research (NIHR) via Comprehensive Local Research Network (CLRN) (UKCRN 15224)
National Institute for Health Research (NIHR) (via West Anglia Comprehensive Local Research Network (CLRN)) (UKCRN 11822)
Cambridge University Hospitals NHS Foundation Trust (CUH) (unknown)
Medical Research Council (G0600717)
Medical Research Council (MC_U106179472)