Effect of vitamin D supplementation during pregnancy on maternal and neonatal outcomes: a systematic review and meta-analysis of randomized controlled trials
Objective: To assess the effects of vitamin D supplementation during pregnancy on obstetric outcomes and birth variables. Design: Systematic review and meta-analysis of randomized controlled trials (RCTs). Setting: Not applicable. Patient(s): Pregnant women and neonates. Intervention(s): PubMed and 5 other research databases were searched through March 2014 for RCTs evaluating vitamin D supplementation calcium/vitamins/ferrous sulfate vs. a control (placebo or active) during pregnancy. Main Outcome Measure(s): Measures were: circulating 25-hydroxyvitamin D [25(OH)D] levels, preeclampsia, gestational diabetes mellitus (GDM), small for gestational age (SGA), low birth weight, preterm birth, birth weight, birth length, cesarean section. Mantel-Haenszel fixed-effects models were used, owing to expected scarcity of outcomes. Effects were reported as relative risks and their 95% confidence intervals (CIs). Result(s): Thirteen RCTs (n ¼ 2,299) were selected. Circulating 25(OH)D leve...