The High Initial Dose of Monitored Vitamin D Supplementation in Preterm Infants.

Inclusion Criteria: * preterm infants with a gestational age of 24+0/7 to 32+6/7 born at our clinic * preterm infants with a gestational age of 24+0/7 to 32+6/7 outborn and admitted to our intensive care unit within 48h after delivery * written informed consent form caregivers for the mother and the child to participate in the study Exclusion Criteria: * infants born at \>32 weeks of gestation * infants with major congenital abnormalities or other severe congenital malformations * infants with genetic disorders (diagnosed before and after birth) deemed incompatible with survival * infants with diagnosed cholestasis * the absence of written informed consent and challenges in communication with caregivers