Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment and no blinding), by inconsistency (unexplained variability in results, and by imprecise results (few patients and wide confidence intervals).
A Cochrane review included 6 studies with a total of 1023 subjects. Women who received vitamin D supplements had higher concentrations of vitamin D in serum at term than those women who received no intervention or a placebo (MD 47.08, 95% CI 23.76 to 70.39;4 trials, n=414), however the magnitude of the response was highly heterogenous. In one trial women who received 1200 IU vitamin D along with 375 mg of elemental calcium per day were as likely to develop pre-eclampsia as women who received no supplementation (RR 0.67; 95% CI 0.33 to 1.35, n=400). Birth weight below 2500 grams was statistically nonsignificantly reduced with vitamin D supplements compared with no treatment or placebo (RR 0.48; 95% CI 0.23 to 1.01; 3 trials, n=463). There were no significant differences in adverse side effects including nephritic syndrome, stillbirths or neonatal deaths between the groups.
Date of latest search: 6.12.2011