Risk of infant anemia is associated with exclusive breast-feeding and maternal anemia in a Mexican cohort.

The WHO recommends exclusive breast-feeding (EBIF) for the first 6 mo of life to decrease the burden of infectious disease. However, some are concerned about the effect of EBIF > 6 mo on iron status of children in developing countries in which anemia is prevalent. This study examines the risk of anemia in relation to the duration of EBIF and maternal anemia in a birth cohort studied between March 1998 and April 2003. All infant birth weights were >= 2.2 kg. All mothers received home-based peer counseling to promote EBF. Infant feeding data were collected weekly. Nurses measured hemoglobin (Hb) values every 3 mo. Hb was measured in 183 infants at 9 mo of age. Anemia at 9 mo was defined as a Hb value < 100 g/L. EBF was defined by WHO criteria and ranged in duration from 0 to 31 wk. At 9 mo, Hb (mean +/- SEM) was 114 +/- 0.9 g/L; 23 children (12.5%) had Hb levels < 100 g/L. EBF > 6 mo, but not EBIF 4-6 mo, was associated with increased risk of infant anemia compared with EBF < 4 mo (odds ratio = 18.4, 95% Cl = 1.9, 174.0). Maternal anemia was independently (P = 0.03) associated with a 3-fold increased risk of infant anemia. These associations were not explained by confounding with other maternal or infant factors. By linear regression, a lower infant Hb at 9 mo was associated with increased EBF duration among mothers who had a history of anemia (beta = -0.07, P = 0.003), but not among mothers with no history of anemia. Infants who are exclusively breast-fed for > 6 mo in developing countries may be at increased risk of anemia, especially among mothers with a poor iron status; greater attention to this issue is warranted.