Does maternal iodine supplementation during the lactation have a positive impact on neurodevelopment of children? Three-year follow up of a randomized controlled trial.

Abstract

The aim of this study was to examine, for the first time, the neurodevelopmental outcomes in children whose mothers received different doses of iodine supplements during lactation. We conducted a follow-up study on children whose mothers participated in a randomized clinical trial to receive placebo, 150µg/day or 300µg/day of iodine until 12months postpartum. Child neurocognitive development was assessed at 36months of age using the Bayley Scales of Infant and Toddler Development Third Edition. Linear mixed-model analysis was preformed to assess iodine supplement dose effects on child cognitive, language, and motor functions. A total of 122 children provided neurodevelopmental data as follows: 300µg/d iodine group: 45; 150µg/d iodine group: 35; and placebo group: 42. Cognitive scores were higher in children whose mothers received 150µg iodine/d compared to children whose mothers received placebo [102.8 (SD 13.2) vs. 99.2 (SD 10.5); β = 4.43, P = 0.032]. However, supplementation with 150µg iodine/d had no effect on language or motor development. No significant differences were observed in cognitive, language, or motor functions between children whose mothers received 300µg iodine/d and those whose mothers received 150µg iodine/d or placebo. Maternal iodine supplementation with 150µg/d during lactation may have a beneficial effect on child cognitive development; however, we found no evidence of either improved or delayed neurodevelopmental outcomes in children whose mothers received iodine supplements at doses higher than recommended. Further randomized controlled trials with larger sample sizes are needed to confirm these results. IRCT201303164794N8; registration date: 2013-05-20.