Individualized Fortification of Breast Milk for Preterm Infants - A Pilot Study

Inclusion Criteria: * Birth weight ≤ 1500g and gestational age \< 32weeks * Tolerating an enteral intake of ≥ 100 ml/kg/d for ≥ 24h Exclusion Criteria: * Infants fed more than 25% of mean caloric intake for a consecutive week with formula milk * gastrointestinal malformation, major congenital anomalies and chromosomal abnormalities * Babies with enterostoma or short gut syndrome * Fluid restriction below * Renal disease * Sepsis * Necrotizing enterocolitis * Hepatic dysfunction