title: Effect of vitamin D supplementation during pregnancy on maternal and neonatal outcomes: a systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To assess the effects of vitamin D supplementation during pregnancy on obstetric outcomes and birth variables.
  
  
  METHODS
  Systematic review and meta-analysis of randomized controlled trials (RCTs).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Pregnant women and neonates.
  
  
  METHODS
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  Thirteen RCTs (n = 2,299) were selected. Circulating 25(OH)D levels were significantly higher at term, compared with the control group (mean difference: 66.5 nmol/L, 95% CI 66.2-66.7). Birth weight and birth length were significantly greater for neonates in the vitamin D group; mean difference: 107.6 g (95% CI 59.9-155.3 g) and 0.3 cm (95% CI 0.10-0.41 cm), respectively. Incidence of preeclampsia, GDM, SGA, low birth weight, preterm birth, and cesarean section were not influenced by vitamin D supplementation. Across RCTs, the doses and types of vitamin D supplements, gestational age at first administration, and outcomes were heterogeneous.
  
  
  CONCLUSIONS
  Vitamin D supplementation during pregnancy was associated with increased circulating 25(OH)D levels, birth weight, and birth length, and was not associated with other maternal and neonatal outcomes. Larger, better-designed RCTs evaluating clinically relevant outcomes are necessary to reach a definitive conclusion.
authors: Department of Obstetrics and Gynecology, University of Zaragoza Faculty of Medicine and Lozano Blesa University Hospital, Zaragoza, Spain. Electronic address: faustino.perez@unizar.es.
authors: Faustino R
authors: FR
authors: Pérez-López
authors: Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
authors: Vinay
authors: V
authors: Pasupuleti
authors: Unit of Analysis and Generation of Evidence in Public Health (UNAGESP), Instituto Nacional de Salud, Lima, Peru; School of Medicine, Universidad Peruana de Ciencias Aplicadas (UPC), Lima, Peru.
authors: Edward
authors: E
authors: Mezones-Holguin
authors: Unit of Analysis and Generation of Evidence in Public Health (UNAGESP), Instituto Nacional de Salud, Lima, Peru.
authors: Vicente A
authors: VA
authors: Benites-Zapata
authors: Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
authors: Priyaleela
authors: P
authors: Thota
authors: Medicine Institute Center for Value Based Care Research, Cleveland Clinic, Cleveland, Ohio.
authors: Abhishek
authors: A
authors: Deshpande
authors: School of Medicine, Universidad Peruana de Ciencias Aplicadas (UPC), Lima, Peru; Health Outcomes and Clinical Epidemiology Section, Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio.
authors: Adrian V
authors: AV
authors: Hernandez
mesh_terms: D015415:Biomarkers / Q000097:blood; D001724:Birth Weight; D016009:Chi-Square Distribution; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control*; D011295:Prenatal Care / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Vitamin D; maternal outcomes; meta-analysis; neonatal outcomes; pregnancy