Human fortified milk is breast milk supplemented with extra nutrients to meet the heightened needs of premature or low-birth-weight infants. This specialized feeding is a common practice in Neonatal Intensive Care Units (NICUs) to provide the components needed for healthy growth and development.
Why Premature Infants Need Fortified Milk
Infants born before 37 weeks of gestation miss the rapid nutrient transfer that occurs during the final trimester. In this period, a fetus accumulates significant stores of fat, protein, and minerals. A premature birth interrupts this process, leaving the infant with low nutrient reserves and higher demands for “catch-up” growth, creating a nutritional gap that standard human milk cannot close.
A premature infant’s needs for protein and calories are substantially greater than those of a term infant. Their daily requirements for these nutrients can be more than double that of a full-term baby. Unfortified breast milk alone does not contain these high concentrations of nutrients needed to support such rapid growth.
The primary objective of fortification is to enhance human milk to better replicate the nutrient-dense environment of late-stage pregnancy. Beyond protein and calories, there is a heightened need for minerals like calcium and phosphorus for bone development. By supplementing breast milk, clinicians can provide a complete nutritional profile that helps the infant’s body and brain develop.
Types of Milk Fortifiers
Fortifiers add concentrated nutrients to human milk to meet a premature infant’s advanced needs. Vitamins and other micronutrients like zinc may also be included for comprehensive support. These supplements are available in two primary forms, distinguished by their source material.
One category is human milk-based fortifier (HMBF), which is derived from the pasteurized breast milk of screened donors. It is processed into a concentrated liquid or powder to be added to the mother’s own milk or donor milk. An exclusive human milk diet using HMBF is used for very low-birth-weight infants or those with a high risk of gastrointestinal complications.
The other common type is bovine-based fortifier (BMBF), derived from cow’s milk. These fortifiers are widely available as sterile powders or liquids, and their proteins are processed to be more easily digestible. Both HMBF and BMBF are effective at promoting growth, and the choice depends on the infant’s health status and hospital protocols.
The Fortification and Feeding Process
Fortifying milk in a NICU is a precise process managed by clinical staff. The preferred foundation is the mother’s own expressed breast milk for its unique immunological benefits. If a mother’s milk is unavailable, pasteurized donor human milk is used as the base.
Clinical staff, such as nurses or dietitians, mix the milk with a fortifier to achieve a nutritional density tailored to the infant’s needs. Available in powdered and liquid forms, fortifiers are added in exact amounts to a measured volume of breast milk. This creates a consistent, nutrient-enriched feed for every administration.
Many premature infants cannot yet coordinate the actions of sucking, swallowing, and breathing for oral feeding. For this reason, fortified milk is often administered through a nasogastric (NG) tube. This thin tube is inserted through the nostril into the stomach, allowing for the safe and controlled delivery of nutrition.
Impact on Infant Growth and Development
The use of fortified human milk has a direct impact on the growth of premature infants, primarily tracked through weight gain. Fortification significantly increases the rate at which these infants gain weight, helping them catch up to the developmental trajectory they would have followed in the womb. This consistent gain indicates the infant is receiving and using the necessary nutrients.
Beyond weight, fortification supports increases in length and head circumference. Head growth is an important measurement because it serves as an indirect indicator of brain growth. Providing adequate nutrition is fundamental during this period of rapid brain development, which normally occurs in the third trimester.
Another benefit is improved bone mineralization. Premature infants are at risk for metabolic bone disease because they miss the in-utero transfer of calcium and phosphorus. Fortifiers add these minerals to the diet, strengthening bones and reducing the risk of fractures. Clinical teams continuously monitor infants for signs of feeding intolerance to ensure the strategy is well-tolerated.