Poster Topical Area: Maternal, Perinatal and Pediatric Nutrition
Location: Hall D
Poster Board Number: 273
Objectives: The primary objective was to determine the effects of prenatal vitamin D supplementation on the insulin-like growth factor (IGF) axis of infants at birth in Dhaka, Bangladesh, a region with a high prevalence of childhood stunting and maternal vitamin D deficiency. Secondary objectives were to compare IGF-I concentrations in this newborn population to those from reference populations in higher resource settings, and to estimate associations between plasma IGF concentrations and newborn size.
Methods: This was a sub-study of the Maternal Vitamin D for Infant Growth (MDIG) trial, a randomized controlled trial in which pregnant women received weekly vitamin D supplementation (4200 IU/week, 16800 IU/week, 28000 IU/week, or placebo) from 17-24 weeks gestation until birth. Plasma IGF-I, IGF-II, IGFBP-1 and IGFBP-3 were quantified in 559 venous umbilical cord samples, and values in each treatment group were compared to placebo. IGF-I concentrations were compared to a published reference range to determine the proportion of the population below the lower bound of the reference range. Associations between IGF protein concentrations and birth anthropometry (length-for-age Z-scores, weight-for-age Z scores, and head circumference-for-age Z-scores) were assessed.
Results: There was a mean difference of 0.95 ng/mL in IGF-I concentrations between the highest dose supplementation group and the placebo group (95%CI: -3.66, 5.55, p=0.69). There were no significant differences in cord blood concentrations of IGF-I, IGF-II, IGFBP-1 or IGFBP-3 between each treatment group and placebo following adjustment for multiple comparisons. For IGF-I, 6% of girls and 23% of boys were below the 2.5th percentile of a published reference range (Figure 1). IGF-I was positively associated with each measure of size at birth (LAZ, HCAZ and WAZ); for example, a 10ng/mL increase in IGF-I corresponded to a 0.13 standard deviation increase in LAZ at birth (95%CI: 0.09, 0.17, p<0.001).
Conclusions: These results do not support the use of prenatal vitamin D supplementation to alter or enhance the IGF axis in the fetus and newborn. Causes of relatively low IGF-I concentrations among newborns in Dhaka have yet to be established.
This study was funded by the Bill and Melinda Gates Foundation.
The Hospital for Sick Children
Toronto, Ontario, Canada