Breastfeeding and growth in rural Kenyan toddlers

Research has not provided unequivocal support for the recommendation to continue breastfeeding until children reach at least age 24 months. In many circumstances, breastfeeding duration is chosen or conditioned by factors other than scientific evidence and recommendations. Even in communities where breastfeeding into the second year is the norm, a significant number of toddlers are weaned before the recommended age. The research reported here was conducted in a rural community of western Kenya. We prospectively followed a cohort of 264 children for 6 months (mean age at baseline, 14.1 +/- 2.4 months) to examine the effect of variable breastfeeding duration on length and weight gain. We found that breastfeeding was positively associated with growth in a manner that we inferred to be causal, the effect being stronger on linear growth than on weight gain. This was despite the fact that in a cohort where 95% were breastfeeding at baseline, the prevalence of stunting (height-for-age below -2 standard deviations of the WHO-NCHS reference) was already 48%. The present paper examines the socioeconomic characteristics, sanitation, morbidity, and complementary feeding practices that define the context of this apparently contradictory relationship. The population was poor, no household had running water, and malaria is endemic in the study area. Complementary feeding was initiated for 93% of the cohort before age 3 months. The weaning diet was bulky (77% energy from carbohydrate), and high in phytate content ([phytate]:[zinc] molar ratio, 28). Diet quality, judged by diversity and animal source food intake, was low. Several micronutrient intakes were below current recommendations, including riboflavin (63%), niacin equivalents (64%), calcium (72%), iron (74%) and zinc (33%). Based on a locally defined socioeconomic status scale, children in higher SES households were breastfed for a shorter duration than were children from poorer households. Sanitation and water consumption modified the effect of breastfeeding duration on growth: the effect was stronger in the absence of a pit latrine and at low water consumption. Our results support the recommendation to sustain breastfeeding in the second year, particularly in economically depressed environments with inadequate sanitation and water supplies.