Effects of maternal vitamin D supplementation on childhood health.

Vitamin D deficiency during pregnancy is associated with an increased risk of health issues in the offspring. Accordingly, recent Endocrine Society guidelines strongly support supplementation in pregnancy, also underlining that without consensus on optimal maternal vitamin D levels, routine screening is currently irrelevant. Knowledge of organ-specific effects of vitamin D and its association with maternal vitamin D status may aid to optimize vitamin D supplementation. This systematic review outlines the proposed next-generation effects of vitamin D supplementation ≥ 400 IU/d, and explores whether such effects are attributed to a specific maternal vitamin D level obtained during pregnancy. A systematic literature search was conducted in PubMed and Embase according to the PRISMA guidelines, focusing on health outcomes from ten days post-partum and beyond. Of the 2,383 screened articles, 39 were included. In 11 of 16 studies, vitamin D supplementation reduced respiratory tract infections in the first years of life. Growth or bone development benefits were observed in six of 12 studies. Positive effects on neurodevelopment and reduced autoimmune risk (diabetes-related antibodies) were noted, although further research is needed to determine the role of vitamin D. Very few studies have measured vitamin D concentrations, but even 1,600 IU/d supplementation was associated with high frequency of infant vitamin D insufficiency. Current recommendations may not ensure sufficient vitamin D levels at birth, among others, increasing the risk of early-life infections. Further studies linking maternal and infant vitamin D levels to specific outcomes would aid in personalized nutritional advice during pregnancy and improve next-generation health.