In the study, very low birth weight babies born in our hospital will be randomized in the closed envelope method, and breast milk fortifier will be started when 50 ml/kg/day breastfeeding volume is reached in one group, and breast milk enrichment will be started when 100 ml/kg/day enteral feeding is reached in the other group. In the study, the babies in these two groups will be compared by making early (nutrition characteristics and premature morbidity) and long-term follow-ups. In this study, a 30% reduction in the transition time to full enteral nutrition between the groups corresponds to a difference of approximately 5 days. In our study, the sample size was determined as at least 78 patients in each group, with a margin of error of 0.05 and a power of 80% to show the 5-day difference between the groups.

Inclusion Criteria:

• Preterm babies born weighing less than 1500 grams

Exclusion Criteria:

• Babies with congenital anomalies
• Infants who develop necrotizing enterocolitis or spontaneous intestinal perforation before starting a breast milk fortifier
• Babies lost before reaching 50 cc/kg enteral nutrition
• Babies who are not breastfed