Fortifying human milk for infants born preterm: What's the evidence?
Infants born preterm are at high risk of multiple nutrient deficiencies. Part of this risk comes from their relatively high nutrient needs required for growth, such as protein. However, they are also born before they can build up stores of nutrients, including micronutrients and minerals like calcium, phosphorus, and zinc. These micronutrients are essential for helping babies build strong bones.
Parent’s milk is the optimal choice for feeding infants born preterm. However, to meet their very high requirements for nutrients, a multi-nutrient fortifier is typically added to the parent’s milk or donor milk. Multi-nutrient fortifiers add extra protein and micronutrients to the milk to meet the higher needs of the baby. Ultimately, the fortifier is meant to add nutrients to the milk to give the infant what they would have gotten in utero if not born preterm.
Research has looked at whether babies grow better when a fortifier is added to their milk. In addition, research has looked at strategies to individualize fortification for infants and whether adding a fortifier to feeds is beneficial after babies are discharged from the hospital. Fortifiers made from human milk have also been explored. We wanted to review the research in this area to summarize what is known to date.
What did we do?
We reviewed evidence from randomized clinical trials looking at outcomes associated with multi-nutrient fortification practices of human milk for infants born preterm. We chose to examine only randomized control trials as the highest quality of evidence which minimizes bias and can show causation.
What did we find?
Infants born preterm grow better in hospital when fed a standard concentration of a multi-nutrient fortifier in human milk. However, the nutrient contents of human milk are known to be quite variable. If the parent’s milk was analyzed to determine fat, protein and carbohydrate content and then fortified based on these values, the infants showed improved weight and length growth compared to the standardized fortification. Another method of individualizing the fortification is to increase or decrease added protein in the milk in response to the infant’s metabolism measured by blood values. This method also resulted in even greater growth while the baby was in the hospital.
Most studies add the fortifier to milk once the babies have established feeding tolerance. However, to date, there is not adequate evidence to inform best practices around the timing of when to begin fortifying milk. There is also not enough evidence to know if all babies should have a fortifier added to their milk after leaving the hospital or if a fortifier made from human milk benefits all babies. Importantly, we did not find studies that looked at whether any of these fortification strategies result in improved outcomes in the long term, including brain development.
You can read the published mini-review here:
What are the next steps?
Given that the research indicates that individualizing the fortifier leads to better growth, we want to learn if it also leads to better long-term development. To answer this question, we are running the MaxiMoM INFORM trial! We will determine if adding protein or fat to milk based on an analysis of each parent's milk or the baby’s bloodwork will result in better neurodevelopment. Stay tuned for our results!
Funding for the MaxiMoM INFORM trial is provided by the Canadian Institutes for Health Research.