The Effect of Vitamin D Administration to Premature Infants on Vitamin D Status and Respiratory Morbidity

This trial objective is to assess whether doubling the daily intake of vitamin D improves serum vitamin D levels and serves as primary prevention of respiratory infections and asthma in premature infants. This is a prospective randomized (1:1) double-blinded trial. The study population will be randomized into two groups (1:1): * Intervention Group - 800 IU of Vitamin D once daily * Control Group - 400 IU of Vitamin D once daily Patients will be followed up for one year after randomization for serum Vitamin D levels and respiratory morbidity.