Systematic Review: Uncertain Impact of Vitamin D Supplementation During Pregnancy on Key Maternal and Neonatal Outcomes – Cochrane Database Syst Rev

Study Design and Population: This Cochrane systematic review evaluates the effects of vitamin D supplementation alone or in combination with calcium and other vitamins/minerals during pregnancy. The analysis included 10 randomized controlled trials (RCTs) with a total of 2,313 pregnant women. The review excluded 20 studies from previous versions due to trustworthiness concerns and incorporated one new study.

Main Findings: The evidence regarding vitamin D supplementation alone was very uncertain for its impact on pre-eclampsia, gestational diabetes, preterm birth, and nephritic syndrome. There is low-certainty evidence suggesting that vitamin D may reduce the risk of severe postpartum hemorrhage and low birthweight, though the possibility of increased risk cannot be excluded. Supplementation with vitamin D plus calcium showed very uncertain effects on preterm birth and low birthweight, with no conclusive data on pre-eclampsia, gestational diabetes, or maternal adverse events. The combination of vitamin D, calcium, and other vitamins/minerals also yielded very uncertain evidence for all outcomes examined.

Implications for Practice: The current evidence does not provide strong support for routine vitamin D supplementation during pregnancy due to the low and very uncertain evidence on key outcomes. Further high-quality RCTs are needed to better understand the effects, particularly concerning maternal adverse events and neonatal health.

Reference: Palacios, C., Kostiuk, L. L., Cuthbert, A., & Weeks, J. (2024). Vitamin D supplementation for women during pregnancy. Cochrane Database of Systematic Reviews, 7(7), CD008873. DOI: 10.1002/14651858.CD008873.pub5.