29530004

PMC5848561

Background

Iron deficiency (ID) is the most common micronutrient deficiency worldwide, with potentially severe consequences on child neurodevelopment. Though exclusive breastfeeding (EBF) is recommended for 6 months, breast milk has low iron content. This study aimed to estimate the effect of the length of EBF on iron status at 6 – 8 months of age among a cohort of Bolivian infants.

Methods

Mother-infant pairs were recruited from 2 hospitals in El Alto, Bolivia, and followed from one through 6 – 8 months of age. Singleton infants > 34 weeks gestational age, iron-sufficient at baseline, and completing blood draws at 2 and 6 – 8 months of age were eligible for inclusion (N = 270). Ferritin was corrected for the effect of inflammation. ID was defined as inflammation-corrected ferritin < 12 μg/L, and anemia was defined as altitude-corrected hemoglobin < 11 g/dL; IDA was defined as ID plus anemia. The effect of length of EBF (infant received only breast milk with no other liquids or solids, categorized as < 4, 4 – 6, and > 6 months) was assessed for ID, IDA, and anemia (logistic regression) and ferritin (Fer) and hemoglobin (Hb, linear regression).

Results

Low iron status was common among infants at 6 – 8 months: 56% of infants were ID, 76% were anemic, and 46% had IDA. EBF of 4 months and above was significantly associated with ID as compared with EBF <  4 months (4 – 6 months: OR 2.0 [1.1 – 3.4]; > 6 months: 3.3 [1.0 – 12.3]), but not with IDA (4 – 6 months: OR 1.4 [0.8 – 2.4]; > 6 months: 2.2 [0.7 – 7.4]), or anemia (4 – 6 months: OR 1.4 [0.7 – 2.5]; > 6 months: 1.5 [0.7 – 7.2]). Fer and Hb concentrations were significantly lower with increasing months of EBF.

Conclusions

Results suggest a relationship between prolonged EBF and ID, but are not sufficient to support changes to current breastfeeding recommendations. More research is needed in diverse populations, including exploration of early interventions to address infant IDA.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1066-2) contains supplementary material, which is available to authorized users.

CDC Public Access

HD052460-01/NH/NIH HHS/United States
1K01AI087724-01/National Institute of Allergy and Infectious Diseases/International
K01 AI087724/AI/NIAID NIH HHS/United States
U19 AI057266/AI/NIAID NIH HHS/United States
Seed Grants Program/Emory + Children's Pediatric Center/International
UL1 TR000454/RR/NCRR NIH HHS/United States
T32 AI074492/AI/NIAID NIH HHS/United States
UL1 TR000454/TR/NCATS NIH HHS/United States
U19-AI057266/National Institute of Allergy and Infectious Diseases/International
T32AI074492/NH/NIH HHS/United States
T32 HD052460/HD/NICHD NIH HHS/United States