Seasonality of growth and the relationship between weight and height gain in children under three years of age in rural Malawi.

AIM: To describe the seasonal pattern of growth and analyse the relationship between weight and height gain in children under 3 y of age.
METHODS: A population-based cohort of 767 children was prospectively followed from birth until 36 mo of age in rural Malawi, southeast Africa. Weight and height measurements were collected at monthly intervals until 18 mo of age and quarterly thereafter. Gains in weight and height and prevalence of malnutrition in different seasons were calculated. The relationship between weight and height gain was analysed using a series of correlation analyses.
RESULTS: Both weight gain and linear growth velocity showed an age-dependent seasonal pattern. After infancy, periods of maximal or minimal height increments systematically occurred 3 mo after those for weight gain. The prevalence of malnutrition also followed a seasonal pattern, peaking a few months after periods of reduced growth. Despite the overall pattern, weight gain and subsequent linear growth were not correlated on an individual level. At any point, however, a child's weight for height was directly, albeit weakly, correlated to height gain in the subsequent 3-mo interval.
CONCLUSION: Growth of children under 3 y of age followed an age-dependent seasonal pattern. The poor correlation between children's weight and height increments suggests that seasonality affected weight gain and linear growth through different mechanisms.