The Effects of Vitamin D Supplementation During Infancy on Growth During the First 2 Years of Life

Context: The relationship between maternal and infant vitamin D and early childhood growth remains inadequately understood. Objective: This work aimed to investigate how maternal and child 25-hydroxyvitamin D (25[OH]D) and vitamin D supplementation affect growth during the first 2 years of life. Methods: A randomized, double-blinded, single-center intervention study was conducted from pregnancy until offspring age 2 years. Altogether 812 term-born children with complete data were recruited at a maternity hospital. Children received daily vitamin D-3 supplementation of 10 mu g (group 10) or 30 mu g (group 30) from age 2 weeks to 2 years. Anthropometry and growth rate were measured at age 1 and 2 years. Results: Toddlers born to mothers with pregnancy 25(OH)D greater than 125 nmol/L were at 2 years lighter and thinner than the reference group with 25(OH)D of 50 to 74.9 nmol/L (P<.010). Mean 2-year 25(OH)D concentrations were 87 nmol/L in group 10 and 118 nmol/L in group 30 (P<.001). When group 30 was compared with group 10, difference in body size was not statistically significant (P>.053), but group 30 had slower growth in length and head circumference between 6 months and 1 year (P<.047), and more rapid growth in weight and length-adjusted weight between 1 and 2 years (P<.043). Toddlers in the highest quartile of 25(OH)D (>121 nmol/L) were shorter (mean difference 0.2 SD score [SDS], P=.021), lighter (mean difference 0.4 SDS, P=.001), and thinner (in length-adjusted weight) (mean difference 0.4 SDS, P=.003) compared with the lowest quartile (<81.2 nmol/L). Conclusion: Vitamin D and early childhood growth may have an inverse U-shaped relationship.

Automated summary

This study found that toddlers born to mothers with high pregnancy 25(OH)D levels were lighter at age 2, and there were significant differences in 25(OH)D levels between the two supplementation groups. Higher dose of vitamin D supplementation showed differences in growth patterns throughout the first 2 years of life.