This group will recieve the current standard of care for infants in the NICU, recieving infant formula that provides less than 400 IU of vitamin D a day.

This group will recieve standard of care infant formulas that provide less than 400 IU of vitamin D a day, in addition they will be supplemented with 400 IU of vitamin D3 daily.

400 IU of vitamin D3 daily. Pts will recieve 1 mL a day with a feeding for 28 days.

Total serum 25(OH)D level is currently considered the best indicator of vitamin D supply to the body from cutaneous synthesis and nutritional intake. For infants, ≤37.5 nmol/L (15 ng/mL) would be considered indicative of deficiency and >50 nmol/L (20 ng/mL) as indicative of vitamin D sufficiency.

Serum C-reactive protein (CRP) is a protein made by the liver and increases when there's inflammation in the body. The upper normal reference levels range from 6 to 20 mg/L as cutoff levels to indicate the presence of sepsis or infection.