Objective: To compare the efficacy of 400 vs 1000 IU oral vitamin D supplementation in preterm neonates of 27 to 34 weeks gestation.
Methods: This double-blind randomized controlled trial allocated preterm babies to receive either 400 or 1000 IU of vitamin D3 (n=60 in each group). Primary outcome was prevalence of vitamin D insufficiency (serum vitamin D levels<20 ng ml(-1)) at 40 weeks of corrected gestational age (CGA).
Results: At term CGA vitamin D insufficiency was significantly lower in the 1000 IU group than in the 400 IU group (2% vs 64.6%, P⩽0.001). Although elevated vitamin D levels were seen in 9.8% of babies on 1000 IU per day, this was not associated with clinical or biochemical evidence of toxicity.
Conclusion: Supplementing preterm babies with 1000 IU of vitamin D3 daily decreases the prevalence of vitamin D insufficiency at term CGA. Excess levels of vitamin D may occur at this dose in some babies.