Vitamin d for preventing rickets in healthy, full term newborns

Objectives: To determine with a systematic review (SR) if Vitamin D, compared to placebo or no treatment, reduces rickets in healthy, full term infants.
Methods:
Types of studies: Randomized controlled trials (RCT) or quasi-randomized controlled trials assessing the efficacy of vitamin D in reducing rickets in newborn infants.
Types of participants: Infants born at term (>=37 weeks gestational age).
Types of interventions: Vitamin D given orally or i.m. given at least for 4 weeks versus placebo or no intervention.
Types of outcome measures: Primary outcome measures include clinical sign of rickets; secondary outcome measures include any of the following: bone mineralization, linear growth, radiological signs of rickets.
Search strategy: A search was done on MEDLINE using the highly sensitive strategy of Dickersin, modified to exclude studies on preterm and low birth weight newborn infants.
Methods of the systematic review: Standard Cochrane systematic review methods were planned. A subgroup analysis was planned to evaluate effects in formula- and breast-fed infants.
Results and conclusions: Only two RCT fulfilling the inclusion criteria were retrived. One study was excluded because comparison was made between different doses of vitamin D. No meta-analysis was therefore performed. The single RCT enrolled 18 healthy, full term, breast-fed infants (9 placebo, 9 vitamin D at 400 U/die); 13 infants were followed up to 52 weeks (7 placebo, 6 vitamin D). Bone mineral content was higher in supplemented infants at 12 weeks, but the difference was no longer significant at 26 and 52 weeks. No infant was reported to have rickets. Based on the results of this review it is concluded that current practice and guidelines are not based on data coming from consistent, well conducted RCTs, but from data coming from observational studies.