Preschool iron-folic acid and zinc supplementation in children exposed to iron-folic acid in utero confers no added cognitive benefit in early school-age

Abstract

In Nepal, antenatal iron-folic acid supplementation improved aspects of intellectual, executive, and fine motor function among school-age children. We examined the impact of added zinc to the maternal antenatal supplement (M-IFAZn) and preschool supplementation from 12 to 36 mo with iron-folic acid (C-IFA) ± zinc (C-IFAZn) on cognitive outcomes compared to maternal iron-folic acid (M-IFA) alone. Children 7-9 y old (n = 780) who participated in early childhood micronutrient supplementation trial during 2001-2004 and whose mothers participated in an antenatal micronutrient supplementation between 1999 and 2001 were followed for cognitive assessments in 2007-2009. Using multivariate analysis of variance and adjusting for confounders, M-IFA with child supplementation (either C-IFA or C-IFAZn) did not impact scores on the tests of general intelligence (Universal Nonverbal Intelligence Test), and executive function (Stroop and go/no go tests) relative to the M-IFA alone. However, children in the C-IFAZn group had slightly lower scores on the backward digit span (-0.29, 95% CI: -0.55, -0.04) and Movement Assessment Battery for Children (1.33, 95% CI: 0.26, 2.40) relative to the referent group, whereas both C-IFA (-1.92, 95% CI: -3.12, -0.71) and C-IFAZn (-1.78, 95% CI: -2.63, -0.92) produced somewhat lower finger tapping test scores (fine motor skills). The combination of M-IFAZn and C-IFA or C-IFAZn did not lead to any outcome differences relative to M-IFA alone. Preschool iron-folic acid ± zinc to children exposed to iron-folic acid in utero or addition of zinc to maternal iron-folic acid conferred no additional benefit to cognitive outcomes assessed in early school age. The late timing of supplementation during preschool may explain the lack of impact of iron and/or zinc.

Trial registration: ClinicalTrials.gov NCT00109551 NCT00115271.