Evaluation of Human Milk Fortifiers in Preterm Infants

Inclusion Criteria: * Birth weight of 700 g-1500 g. * ≤ 32 weeks and 0 days GA at birth. * Appropriate for GA (AGA). * Enteral feeding of human milk initiated by 21 days of life (birth date is day of life 0). * Mother agrees to provide human milk as the exclusive feeding during the study period; use of donor milk is permitted if the plan is that it will be fortified. * Parent(s) agrees to allow infant to receive both human milk and HMF. * Singleton or twin births only. Exclusion Criteria: * Enteral feeding of preterm infant formula or HMF for \> 7 days. * Expected to be transferred to another facility and will not be able to be followed for at least 15 days. * Serious congenital abnormalities or underlying disease that may affect growth and development. * 5 minute APGAR ≤ 4. * Steroids used at the time of randomization. * Grade III or IV periventricular/intraventricular hemorrhage (PVH/IVH). * Mechanical ventilator dependence. * Maternal incapacity: including maternal cocaine or alcohol abuse during pregnancy or current, or if the mother or infant is currently receiving treatment consistent with HIV therapy. * Infant has a history of major surgery (intra-thoracic or intra-abdominal procedures or other surgery requiring general anesthesia). * Asphyxia defined as progressive hypoxemia and hypercapnia with significant metabolic acidemia characterized by APGAR score \<3 at 10 minutes, seizures within the first 12 hours of life, or a cord blood gas \< 7.0 and seizures and/or severe tonic abnormalities in the first 12 hours of life (24). * Confirmed necrotizing enterocolitis (Bell's Stage II or III, Appendix J) or confirmed sepsis (positive culture requiring antibiotic treatment). * Infant has any other condition that, in the opinion of the investigator, precludes participation in the study. * Participation in another study that has not been approved as a concomitant study by AN.