Prevalence and predictors of iron deficiency in exclusively breastfed infants at 6 mo of age: comparison of data from 6 studies

Our objective was to determine which subgroups of exclusively breastfed infants may be at risk of iron deficiency prior to 6 mo. We compared the prevalence of low plasma ferritin concentration (< 12 ug/L) and iron deficiency anemia (IDA, ferritin < 12 ug/L and Hb < 105 g/L) at 6 mo among 404 infants in 6 different studies in Ghana, Honduras, Mexico and Sweden who had a birth weight > 2500 g and were exclusively or predominantly breastfed or had not received any iron‐fortified formulas or milks. Infants with elevated C‐reactive protein concentration (8%) were excluded. The percentage with low ferritin was 6% in Sweden, 17% in Mexico, 13–25% in Honduras and 12–37% in Ghana. The percentage with IDA was 1% in Sweden, 4% in Mexico, 5–11% in Honduras and 8–15% in Ghana. With data pooled from all studies, the key predictors of low ferritin (20% overall) were immediate umbilical cord clamping (AOR 4.5 [1.9, 11.0]), male sex (AOR 4.0 [2.2, 7.3]) and birth weight < 3 kg (AOR 2.3 [1.3, 4.0]). The predictors of IDA (8% overall) were male sex (AOR 7.2 [2.4, 21.6]), birth weight < 3 kg (AOR 3.0 [1.4, 6.6]), weight gain since birth above the median (AOR 3.1 [1.2, 7.9]) and immediate cord clamping (AOR 3.7 [0.8, 16.5]). These variables could be used to identify which exclusively breastfed infants are at risk of IDA before 6 mo.