| Aim & Methods: To determine the associations between gestational ID and child cognitive, motor development and growth at 5 years of age in rural Bangladesh, we studied a cohort of 381 children born to mothers participating in a large vitamin A or beta-carotene supplementation trial in Gaibandha District, Bangladesh. Maternal gestational iodine status was measured by urinary iodine excretion (UIE), thyroglobulin (Tg) and free thyroxine (fT4) in early (1st-2nd trimester, TM) and late (3rd TM) pregnancy. Child cognition and motor skills were assessed using five modified subtests from the Wechsler Preschool and Primary Scale of Intelligence-III (WPPSI-III), and eight age-appropriate standard tests from the second edition of the Movement of Assessment Battery for Children (MABC-2) at 5 years of age (median age at testing: 60 months; interquartile range, IQR: 60-61 months). Child growth variables were weight (kg), length/height (cm), head circumference (HC, cm), their Z-scores (WAZ, LAZ, HCAZ), chest (CC, cm) and mid-upper arm (MUAC, cm) circumferences at birth, 3, 6 and 60 months of age. Potential confounders were assessed during pregnancy, infancy or at the 5 year visit, including socio-economic status, home environment, maternal cognition, parity, child's nutritional status and iodine levels in household salt. Gestational iodine status was treated as categorical variables (four ID groups) based on UIE in early, late or across (mean UIE computed over early and late pregnancy) pregnancy, respectively (0∼19 mug/L, severe ID; 20∼49 mug/L, moderate ID; 50∼99 mug/L, mild ID; and ≥100 mug/L, adequate group), or continuous variables as UIE. The non-parametric Jonckheere-Terpstra test was used to evaluate the significance of trend between gradations of iodine deficiency (ID) and performance on cognitive and motor tests. Unadjusted and adjusted linear regression analysis was conducted.;Results: The prevalence of gestational ID (UIE70% among the study women. Serum Tg and fT4 at pregnancy of these mothers apparently remained within the normal ranges, indicating they were clinically euthyroid. After confounders were adjusted for, children born to mothers who were mildly (beta= -1.51, p=0.050), moderately (beta= -1.22, p=0.088), and severely (beta= -2.37, p=0.039) iodine deficient in early pregnancy had worse performance on vocabulary test than the adequate group. Children born to mothers who were severely iodine deficient in early pregnancy also had worse performance on the overall verbal scale (3.09 points lower), the balance skills (1.09 points lower) and overall MABC-2 test (1 point lower) than the adequate group. (P<0.10) With respect to maternal UIE in late pregnancy, children in the severe ID group had lighter weight (beta=-0.156), shorter length (beta=-0.807), smaller WAZ (beta=-0.397), LAZ (beta=-0.433), and chest circumference (beta=-0.736) than the adequate group.(P<0.05) Maternal UIE in early, but not late, pregnancy was positively associated with postnatal 5 year increments in weight (beta=0.0023), WAZ (beta=0.0016), height (beta=0.0051), HAZ (beta=0.0021), HC (beta=0.0018), and HCAZ (beta=0.0013) . (all p values <0.05 except for HCAZ: p<0.10).;Conclusion: Gestational ID may impair the development of child certain cognitive (eg. language related abilities) and motor functioning at an age just prior to school entry in a typical rural area of South Asia. Maternal iodine status, measured by pregnancy UIE and reflecting iodine availability to the fetus, is a determinant of child growth over the first five years of life. (Abstract shortened by UMI.). |
