Preterm infants require higher nutritional intakes during the neonatal phase than they do at any other stage of their development. Standard volumes of human milk alone do not offer sufficient nourishment to these infants. There are multiple options for fortifying human milk, which vary depending on whether the fortifier is derived from bovine sources (B-HMF) or human sources (H-HMF). Fortifying human milk has been proven to enhance growth in preterm infants without raising the risk of necrotizing enterocolitis (NEC), though it could potentially affect feeding tolerance. Changes in blood flow and oxygen levels in the intestines are commonly observed in infants experiencing feeding intolerance. Research indicates that feeding a mother's own milk (MOM) doesn't affect splanchnic (intestinal) oxygenation, whereas it decreases when feeding bovine-derived human milk fortifiers (B-HMF) or preterm formula, indicating greater oxygen requirements in the intestines of preterm infants fed these alternatives.

The goal of this clinical trial is to compare the effect of H-HMF and B-HMF on splanchnic oxygenation in infants less than 30 weeks.

The fortification of human milk has been proven to enhance growth without raising the risk of necrotizing enterocolitis, although it may affect feeding tolerance.

Non-invasive techniques like Doppler ultrasonography of the superior mesenteric artery (SMA) and near-infrared spectroscopy (NIRS) have been utilized to evaluate mesenteric blood flow and intestinal oxygenation in preterm infants. Numerous studies have investigated the relationship between SMA flow and feeding intolerance. Findings indicate a significant correlation between increased mean Superior Mesenteric Artery blood flow velocity and early tolerance of enteral feeding. Moreover, research suggests a higher incidence of necrotizing enterocolitis (NEC) in preterm infants exhibiting increased resistance patterns of SMA blood flow velocity on the first day.

Non-invasive monitoring methods offer the ability to assess the impact of various fortification products on intestinal perfusion and oxygenation. This could aid in determining the most suitable fortification product to minimize episodes of feeding intolerance.

Inclusion Criteria:

1. Preterm infants born <30 weeks' gestation age and less than 1500g of weight.
2. Admitted in Neonatal Intensive Care Unit at Foothills Medical Center
3. Reached full fortified enteral feed and at least 21 days of chronological age.

Exclusion Criteria:

1. Chromosomal or major congenital anomalies
2. Infants diagnosed with NEC.

Randomizing the participants to either Bovine-HMF or Human Milk based-HMF will mask the Investigator