Meeting the preterm infants need for protein is difficult due to their very high growth rate and thus high protein need. Breast milk is always the preferred choice for preterm infants however it has to be fortified. However the protein content of fortifiers should be kept low when the protein content of the breast milk is high because too high intake can be dangerous for premature babies. This leads preterm infants to usually have very low protein intake. Other reasons for the low intake include slow feeding advancement and low feeding volumes.