Survey of vitamin D supplementation practices in extremely preterm infants.

Despite the prevalence of vitamin D deficiency in extremely preterm (EP) infants at birth, optimal levels and supplementation strategies remain debated. Recent studies have suggested benefits of early high-dose vitamin D supplementation (800 IU/day) for reducing complications like bronchopulmonary dysplasia, infections, and disability. There is US center variation in timing and dose of vitamin D supplementation, being the most common regimen 400 IU/d started after established feedings (≥120 ml/kg/day). These findings inform and highlight the need for clinical trials of usual vs. early, higher-dose vitamin D supplementation to advance clinical outcomes and define desirable blood levels of EP infants.