Preterm newborns are born with lower vitamin D stores. Although vitamin D supplementation is recommended there is no consensus regarding the adequate dose of supplementation for preterm infants.

Vitamin D is a fat-soluble vitamin that is either taken by dietary sources or synthesized upon exposure to sun light. Although major function is on bone metabolism, in recent years other effects of Vitamin D attracted attention. Low neonatal vitamin D levels were reported to be associated with increased risk of respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD) and sepsis.

Vitamin D level in the fetus and the newborn is mostly dependent on maternal vitamin D levels. Most of the vitamin D is transferred to the fetus during third trimester and as a result preterm newborns especially those with <32 weeks gestational age are born with lower vitamin D stores. But there is no consensus regarding the adequate dose of vitamin D supplementation for preterm infants. The American Academy of Pediatrics recommends supplementation of 200-400 IU/d vitamin D for preterm infants. And the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) recommends 800-1000 IU/d vitamin D supplementation for preterm infants.

Inclusion Criteria:

• Preterm infants with gestational age 24 to 32 weeks who achieved at least 75% of total nutrition by enteral feedings in postnatal 2 weeks

Exclusion Criteria:

• perinatal asphyxia,
• major congenital or chromosomal anomalies,
• those with no expectation of survival in first 2 weeks
• those that total parenteral nutrition was not ceased by the first 2 weeks