Breast-feeding is associated with improved growth in length, but not weight, in rural Senegalese toddlers.

BACKGROUND: Prolonged breast-feeding is frequently associated with malnutrition in less-developed countries, even after adjustment for socioeconomic confounders. However, in rural Senegal, breast-feeding is prolonged when the child is stunted.
OBJECTIVE: We aimed to test whether the lower height-for-age of children weaned late is explained by their height before weaning or whether prolonged breast-feeding is associated with impaired growth.
DESIGN: A cohort of 443 Senegalese children recruited from dispensaries at 2 mo of age were visited in their homes at 6-mo intervals when they were approximately 1.5 to 3 y of age. Weight, length, arm circumference, and triceps skinfold thickness were measured. Six-month increments were analyzed in relation to breast-feeding (breast-fed compared with weaned children or breast-feeding duration), season, and maternal housing with use of multiple linear regression.
RESULTS: The mean duration of breast-feeding was 24.1 mo (quartiles 1 and 3: 21.9 and 26.4). Height-for-age at the age of 3 y was negatively associated with age at weaning (P < 0.01), but this association disappeared after adjustment for height-for-age in infancy. Length increments were significantly greater in both the second and third years of life in children breast-fed for longer durations (P < 0.05) and tended to be greater in breast-fed than in weaned children in the second year of life (P = 0.05). In the third year of life, breast-fed children had greater length increments than did weaned children in the subgroup with poor housing (P for interaction < 0.05). Growth in weight did not differ significantly according to breast-feeding.
CONCLUSION: Prolonged breast-feeding improved linear growth, and the negative relation between height-for-age and duration of breast-feeding was due to reverse causality.