Vitamin D in preterm infants: A prospective observational study

Aim Preterm infants are at increased risk of vitamin D deficiency as a result of both maternal deficiency and inadequate supplementation. The quantity and effectiveness of vitamin D supplementation in preterm infants are unclear. The aim of this study was to evaluate the natural history of vitamin D status in preterm infants and the effectiveness of the hospital's nutritional practices in meeting current supplementation recommendations. Methods A prospective observational study was undertaken in the Neonatal Unit at the Women's and Children's Hospital, Adelaide. Enrolled infants received a standardised nutrition protocol with emphasis on vitamin D supplementation. The main outcome measure was a comparison of the proportion of vitamin D-deficient infants (25(OH)D < 50 nmol/L) at birth versus 36 weeks post-menstrual age/discharge. Results Twenty-eight infants born between 30 and 36 weeks gestation were enrolled. The proportion of vitamin D-deficient infants decreased from initial to final measurement (32.1% vs. 7.1%, P = 0.016), whereas mean (standard deviation) 25(OH)D₃ increased over the same period (58.4 (18.4) versus 82.9 (29.2) nmol/L, P < 0.001). Mean vitamin D intake was 643.6 (285.3) IU/day. Conclusions Current nutritional practices are effective in meeting recommendations regarding vitamin D intake and result in a lower proportion of deficient infants at 36 weeks post-menstrual age/discharge.