Breast feeding and seasonal determinants of child growth in weight in East Bhutan.
In the remote eastern part of Bhutan, all 113 children born during April-September 1990 in 45 villages in Wamrong subdistrict and who were alive in October 1990 were enrolled in a prospective cohort study and visited monthly until the end of May 1993. The study aimed to examine how diarrhea, respiratory tract infections (RTIs), and season affect child growth in weight and how breast feeding influences growth. The warm, humid monsoon season (June-September) was associated with a marked increase in the incidence of diarrhea (odds ratio [OR] = 2.47; p < 0.0001) and with a significant reduction in child growth (p < 0.0001). Further analysis including the interaction of the monsoon season with other variables revealed that both RTIs and diarrhea were associated with reductions in weight gain (p = 0.003 and < 0.0001, respectively). Diarrhea also had a larger negative effect on weight gain during the monsoon season than during the dry season (p < 0.0001). In fact, during the monsoon season, the average weight loss was 7.4 g/day, while any weight loss during the other seasons was minimal. No child aged 13-36 months was fully breast fed. The median duration of breast feeding was 28 months. Breast feeding was associated with a marked reduction in the incidence of both diarrhea and RTIs (OR = 0.51 and 0.63, respectively; p = 0.0016 and < 0.0001, respectively). Children who were breast fed lost less weight during the monsoon season than non-breast-fed children (2.5 vs. 7.5 g/day; p < 0.01). During the monsoon season, non-breast fed children with diarrhea lost, on average, 5.3 g/day, while breast fed children with diarrhea gained, on average, 1.8 g/day (p < 0.01). These findings show that partial breast feeding in the second and third years of life reduces the incidence of diarrhea and RTIs, especially during the monsoon season, and protects against the negative effect on growth associated with these two conditions. In conclusion, mothers should continue to partially breast feed during the monsoon season.