Full breastfeeding duration and risk for iron deficiency in U.S. infants

Background: National and international authorities recommend exclusive breastfeeding for an infant's first 6 months. Effects of these recommendations on iron status of U.S. children are unknown. Objective: To ascertain if full breastfeeding for 6 months versus 4 months places U.S. children at greater risk for iron deficiency. Design/Methods: Data regarding 2268 children ages 6 to <24 months from NHANES III, a nationally representative cross-sectional survey conducted from 1988-1994, were analyzed. Similar analyses were conducted for 526 children ages 12 to <24 months from NHANES 1999-2002. Anemia (low hemoglobin or history of anemia) and iron status (serum ferritin) were compared for five groups: formula fed only (n = 1142), or full breastfeeding for: <1 month "FullF<I" (n = 425), 1 to <4 months "FullBF1-3+" (n = 343), 4 to <6 months "FullF4-5+" (n = 222), and ≥ 6 months "FullBF6+" (n = 136). Laboratory data were available for children 12 to 24 months (n = 745). SUDAAN software was used to account for the complex sampling design. Logistic regression adjusted for confounding factors. Results: In unadjusted analyses WHANES III), 10.0% of "FullBF6+" versus 2.3% of "FullBF4-5+" had a history of anemia (p = 0.007) but unadjusted between group serum ferritin and hemoglobin differences were insignificant in both surveys. Adjusting for birth weight and demography revealed persistently lower risk of history of anemia (NHANES III, odds ratio [OR] 0.20, confidence interval [CII 0.06, 0.63) and low serum ferritin (NHANES 1999-2002, OR 0.19, Cl 0.06, 0.57) but not low hemoglobin at time of survey "FullBF4-5 +" versus "FullBF6+". Conclusions: Young children in the United States fully breastfed for 6 months may be at increased risk of iron deficiency. Adequate iron may not be provided by typical complementary infant foods. Healthcare providers should be vigilant to preventiron deficiency in this group of infants.