Vitamin D for very preterm infants-determining the how, when, and why.

A recent survey study found that 400 IU/day vitamin D is the most common dose in United States neonatal intensive care units. Results of clinical trials are inconsistent, and, therefore, have not determined the optimal vitamin D dose for efficacy and safety in the neonatal intensive care unit. Future studies must consider the unique attributes of perinatal vitamin D metabolism and the potential role of vitamin D in immune function and organ development. IMPACT: Preterm infant vitamin D metabolism is a complex yet important area of research.