We hypothesize that premature infants who receive their mothers' expressed breast milk supplemented with liquid protein early in their hospitalization will have a growth velocity in the first 28 days of life that is 20% greater than the growth velocity of premature infants that do not receive protein fortification.

Inclusion Criteria:

• inborn at Mount Sinai Medical Center
• gestational age between 26 0/7 weeks and 32 6/7 weeks gestation
• plan by family for their infant to receive human milk feeds

Exclusion Criteria:

• outborn infants
• gestational age < 26 0/7 weeks or > 33 0/7 weeks
• major congenital anomalies including cardiac disease, inborn errors of metabolism etc.
• sepsis and/or other serious clinical complication precluding initiation of enteral feeds
• plan by family for their infant to receive primarily preterm infant formula.