Evidence suggests that adequate vitamin D status in infancy plays a role in improving bone health and preventing disease, including type 1 diabetes, infections, and asthma. The objective of this study was to provide newborn hospitalized infants with American Academy of Pediatrics recommendations of 400 IU/day vitamin D-3 and measure the effect on serum 25(OH)D levels.

This trial was conducted August 2009 to June 2010. Infants were randomized to a control were measured from cord blood, every 7 days, and at discharge. Intact parathyroid hormone was measured at discharge.

Fifty-two infants <32 weeks gestational age who received formula feedings during their neonatal intensive care unit hospitalization.

Patient characteristics for each treatment group were summarized using descriptive statistics. The Mann-Whitney test was used to compare continuous variables, and categorical variables were compared using the χ² test or Fisher's exact test. The Pearson correlation coefficient was used to look at associations between continuous variables.

The mean cord blood level for all participants was 17.6±7.0 ng/mL. White infants had significantly higher 25(OH)D levels than non-white infants (P=0.0003). The mean 25(OH)D level at discharge of the supplemented group was 23.1±7.0 ng/mL (57.66±17.47 nmol/L), the mean 25(OH)D level of the unsupplemented group was 17.8±4.7 ng/mL (44.43±11.3 nmol/L), (P=0.007). Serum 25(OH)D showed a positive correlation with serum calcium in the first week of life (r=0.44, P=0.003) and negative correlation with parathyroid hormone levels at discharge (r=−0.35, P=0.02).

In newborn hospitalized infants, vitamin D-3 supplementation of 400 IU/day increased mean 25(OH)D levels from 17 ng/mL at birth to 23.1 ng/mL at discharge. Lower 25(OH)D levels were correlated with hypocalcemia during the first week of life, and elevated parathyroid hormone levels at discharge.