Age at Weaning and Infant Growth: Primary Analysis and Systematic Review

Abstract

ObjectiveTo test whether earlier age at weaning (age 3-6 months) may promote faster growth during infancy.Study designWeaning 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.ResultsAlmost 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.ConclusionIn 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.

Following the World Health Organization's Recommendation of Exclusive Breastfeeding to 6 Months of Age Does Not Impact the Growth of Rural Gambian Infants

“…It was not possible to explain this difference by environmental, maternal, or infant characteristics; and we therefore tested the possibility of reverse causality. The method proposed by Vail et al (26) was applied, including infants who were still EBF at 3 mo of age, testing whether their mean weight, length, and z score changes between 2 wk and 3 mo of age were associated with subsequent age of discontinuation of EBF. The same analysis was conducted in infants who were still EBF at 4 mo of age.…”

“…Second, this observation could reflect reverse causality, with mothers in this community choosing to continue EBF if their infant was growing well. Research from the United Kingdom has shown that rapid weight gain between birth and 3 mo of age predicted subsequent earlier age of weaning (26). Kramer et al (27) found contrary results: a low WAZ (<−1) at 1 mo increased the risk of both weaning and discontinuation of EBF by 2 mo of age in a Belarusian population.…”

Early-life exposures predicting onset and resolution of childhood overweight or obesity

“…Later solids introduction doubled the odds of resolution (OR 2.29, CI 1.08 to 4.88, p=0.03). In addition, because larger infants start solids earlier,24 we further adjusted for birth weight (OR 2.13, CI 0.91 to 4.99, p=0.08).…”

Changes in the coordination between respiration and swallowing from suckling through weaning

“…However, the improved efficiency in drinking developed over infancy [23] is retained through weaning. In many mammalian species, including pigs and humans, a period of overlap exists between the onset of solid food intake and the cessation of maternal milk consumption [24][25][26]. Maintaining efficient aerodigestive function in liquid consumption developed through infancy allows the weanling to extract maximum nutrition from increasingly infrequent milk feeds while it navigates the challenges of eating solid food.…”