Pregnancies are helped 10 ways by Vitamin D - umbrella analysis

01/04/2026 - Vitamin D Wiki
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Vitamin D supplementation during pregnancy and maternal and neonatal outcomes: results from a quantitative umbrella meta-analysis

BMC Pregnancy and Childbirth April 2026

Background

This umbrella meta-analysis aimed to examine the effect of prenatal vitamin D supplementation on maternal and neonatal outcomes.

Methods

Scopus and PubMed were searched up to September 2024 to include relevant studies. The outcomes included gestational diabetes mellitus (GDM), preeclampsia, cesarean section, preterm delivery (PTD), low birth weight (LBW), small for gestational age (SGA), stillbirth, neonatal mortality, birth weight, birth length, and head circumference at birth. Standardized mean difference (SMD) and relative risk (RR) with their 95% confidence intervals (CI) were used as effect sizes to pool the data using a random effects model.

Results

Thirty-five studies with 188,370 participants were included. Vitamin D supplementation lowered the risk of

• GDM (RR = 0.68, 95%CI: 0.53 to 0.88),
• preeclampsia (RR = 0.62, 95%CI: 0.56 to 0.69),
• PTD (RR = 0.77, 95%CI: 0.65 to 0.90),
• LBW (RR = 0.67, 95%CI: 0.54 to 0.84),
• SGA (RR = 0.73, 95%CI: 0.63 to 0.85),
• stillbirth (RR = 0.77, 95%CI: 0.62 to 0.95), and
• neonatal mortality (RR = 0.58, 95%CI: 0.40 to 0.84), while also
• enhanced birth weight (SMD = 75.68, 95%CI: 48.99 to 102.36),
• birth length (SMD = 0.25, 95%CI: 0.18 to 0.33), and
• head circumference (SMD = 0.15, 95%CI: 0.06 to 0.23).
• These effects were observed with lower doses of vitamin D ((< 50,000 IU/week), shorter intervention periods (< 14 weeks), and among older participants ((≥ 27 years). Moreover, vitamin D supplementation was linked to the reduced risk of cesarean deliveries in some subgroups.

Conclusions

Prenatal vitamin D supplementation may be associated with a lower risk of certain adverse maternal and neonatal outcomes and may improve birth anthropometric measurements.