Following the World Health Organization’s recommendation of exclusive breastfeeding to six months of age does not impact the growth of rural Gambian infants

Background: The World Health Organization (WHO) recommends exclusive breastfeeding (EBF) for the first six months of life. Objective: The objective of this study is to assess the benefit to growth of EBF to six months in a large sample of rural Gambian infants at high risk of undernutrition. Methods: Infants with growth monitoring from birth to two years of age (n=756) from the Early Nutrition and Immune Development (ENID) trial (clinical trial registry ISRCTN49285450) were categorised as exclusively breastfed if only breastmilk and no other liquids or foods were given. EBF status was entered into confounder-adjusted multilevel models to test associations with growth trajectories using more than 11,000 weight-for-age (WAZ), length-for-age (LAZ) and weight-for-length (WLZ) observations. Results: Thirty-two percent of infants were exclusively breastfed to six months. Mean age of discontinuation of EBF was 5.2 months, and growth faltering started around 3.5 months of age. Some evidence for a difference in WAZ and WHZ was found between infants who were exclusively breastfed to six months (EBF-6) and those who were not (nEBF-6), at six and 12 months of age, with EBF-6 children having a higher mean z-score. The difference in z-scores between the two groups were however small in magnitude (at six months of age: +0.147 WAZ; 95%CI: -0.001, 0.293, +0.189 WHZ; 95%CI: 0.038, 0.341). No evidence for a difference between EBF-6 and nEBF-6 infants was observed for LAZ at any time-point (6, 12 and 24 months of age). It was further found that a higher mean WLZ at three months of age was associated with a subsequent higher mean age at discontinuation of EBF, implying reverse causality in this setting (coefficient 0.060, 95%CI: 0.008, 0.120). Conclusion: This study suggest that exclusive breastfeeding to six months has limited benefit to the growth of rural Gambian infants.