Vitamin D supplementation during pregnancy benefits offspring

Michael G Burke, MD

Infants born to mothers who receive vitamin D supplementation while pregnant are at reduced risk of being small for gestational age (SGA) and experience improved growth during infancy, with no increased risk of fetal or neonatal mortality and congenital malformation. These were major findings of a systematic review and meta-analysis of 24 randomized controlled trials involving 5405 participants.

The meta-analysis revealed other benefits of maternal vitamin D supplementation, including higher neonatal vitamin D status. (Bolus or regular dose supplements were equally effective in improving vitamin D levels.) Additional positive outcomes of vitamin D supplementation were higher calcium levels and Apgar scores; greater neonatal skinfold thickness; greater weight (at birth and at 3, 6, 9, and 12 months); and greater height (at 3, 6, 9, and 12 months).

Early or late administration (before or after 20 weeks’ gestation) of vitamin D supplementation and dose size affected some outcomes. Vitamin D supplementation increased birth weight only when initiated late, and vitamin D supplementation at 2000 IU/d or less was associated with reducing the risk of fetal or neonatal mortality and of SGA, whereas larger doses were not (Bi GW, et al. JAMA Pediatr. 2018;172[7]:635-645).

Thoughts from Dr. Burke

More than 100 years after scientists first suggested that an unidentified fat-soluble substance prevented and treated rickets, we still have plenty to learn about vitamin D. Researchers are compiling a lengthening list of body functions this vitamin affects well beyond bone health and calcium metabolism. Meanwhile, evidence of widespread vitamin D deficiency grows as we retreat to the indoors, away from natural sunlight.