Vitamin D During Pregnancy Benefits Outcomes in Newborn

Vitamin D, a fat-soluble nutrient, plays critical roles in calcium absorption, metabolism, and maintaining bone health. Low vitamin D level status is common enough during pregnancy to be a problem of public health proportions, yet remains relatively under-recognized and under-treated. Low vitamin D levels during pregnancy may expose the offspring to a sub-optimal nutritional milieu. Because the mother is the sole source of all vitamin D for the developing fetus, adequate maternal vitamin D levels are a must to ensure it meets the increased demand of fetal growth and development.

Multiple prior studies have suggested that low maternal Vitamin D levels during critical phases of fetal development and may have long-term effects on offspring health outcomes. As a result, during the past few decades, multiple randomized clinical trials (RCTs) have assessed the effect of vitamin D supplement during pregnancy on maternal, neonatal, infant, or child outcomes. However, the current state of the science remains highly divided as the results of the RCTs have been inconsistent and contradictory. There has till date been a lack of convincing evidence from systematic reviews and meta-analyses to study the question of the association between vitamin D supplementation during pregnancy and offspring growth, morbidity, and mortality.

Given the high prevalence of low vitamin D during pregnancy and the public health importance of clarifying the role of vitamin D during pregnancy in offspring health, a group of Canadian researchers recently conducted a systematic review and meta-analysis of RCTs with aims to evaluate the effectiveness and safety of vitamin D supplementation during pregnancy on offspring outcomes. Bi et al.

Published recently in JAMA PEDIATRICS, this systematic review and meta-analysis of twenty-four clinical trials (after screening over 700 studies) involved over 5000 participants to study this question. Essentially, this study is a synthesis and combined analysis of all published medical literature studying vitamin D supplementation and infant health. This study reported that Vitamin D supplements during pregnancy was associated with almost a 30% lower risk of infant being small for gestational age (SGA) and that Vitamin D supplementation was not associated with risk of fetal or neonatal mortality or congenital abnormality.

Furthermore, neonates who did have prenatal vitamin D supplementation had higher mean vitamin D and calcium levels at birth and higher mean weight at birth by 75 g, higher mean weight at 3 months by 210 g and higher mean weight at 6 months, 9 months and 1 year by about 300-500 gm. They reported that low-dose vitamin D supplementation (≤2000 IU/d) was associated with a two-thirds reduced risk of fetal or neonatal mortality.

The authors conclude that Vitamin D supplementation during pregnancy is associated with a reduced risk of neonate being small for gestational age and improved infant growth in the first year of life without any associated risk of fetal or neonatal mortality or congenital abnormality. Vitamin D supplementation with doses of 2000 IU/d or lower during pregnancy may reduce the risk of fetal or neonatal mortality.

About the Author

Dr. Ruchika Goel is an Asst. Professor of Pediatrics and Internal Medicine, Simmons Cancer Institute at SIU School of Medicine and an Adjunct Asst. Professor in School of Medicine, Johns Hopkins University. She is a mother of twins, a dedicated pediatrician, and an enthusiastic traveler and writer.