Comparing benefits of donor breast milk to formula for very low birth weight babies

Babies who are born very early (before 32 weeks gestation) and/or at very low weights (less than 1,500 grams) are among the most fragile of all paediatric patients, typically facing serious medical issues and requiring care in a Neonatal Intensive Care Unit (NICU). In addition to underdeveloped organs and risk of neurodevelopmental issues, preterm and very low birth weight babies are at risk of a severe bowel emergency called necrotizing enterocolitis, which involves the damage and potential destruction of the intestinal tissue. This disease affects approximately six per cent of very low birth weight infants each year, making it one of the most common causes of death and long-term complications in this population.

As a neonatologist and a PhD-trained dietitian, we have spent our careers working to improve outcomes for babies and supporting breastfeeding. While there is already strong evidence to suggest that breastfeeding is associated with a variety of benefits including reduced risk of childhood infections, and may play a role in the prevention of overweight and diabetes in healthy, full-term infants, we launched a research program a decade ago to figure out how to ensure the same advantage could be provided to vulnerable hospitalized infants, specifically very low birth weight infants.

Breastfeeding initiation rates in Canada are now at an all-time high for healthy newborns, but for many reasons related to preterm birth, up to two thirds of mothers of very low birth weight infants are unable to provide a sufficient volume of breast milk to their infant. A variety of factors may limit breast milk production in these cases, including immaturity of the breast cells that make milk, maternal illness, breast pump dependency, and stress. In addition to the health benefits attributed to mother’s milk for full-term, healthy infants, previous studies have shown that use of mother’s milk in very low birth weight infants is associated with a reduction in necrotizing enterocolitis. It is also associated with a reduction in severe infection, improved feeding tolerance and more rapid hospital discharge.

Ten years ago, along with our inter-professional colleagues at 21 NICUs in the Greater Toronto and Hamilton areas, we began to examine whether using donor breast milk as a supplement to mother’s milk would improve health outcomes of very low birth weight infants when mother’s milk was not available.

In our new study published Nov. 8 in JAMA, we show that when sufficient amounts of mother’s milk are not available, providing donor milk reduces the risk of necrotizing enterocolitis compared to using preterm formula as a supplement during initial hospitalization, with a risk of 1.7 per cent with donor milk, versus 6.6 per cent with formula. The findings are especially important in that the reduction of necrotizing enterocolitis occurs even when extra nutrients are added to the donor milk to support growth and development.

Our research also compared effects of donor milk and formula on brain development. We found that using donor milk did not improve measures of brain development at two years compared to formula.

One hypothesis as to why we did not see an improvement in brain development with donor milk – which both our and other’s research has demonstrated with mother’s milk – is that the processing of donor milk may remove components necessary for brain development. We are working with our colleagues on improving how we process donor milk to better retain heat-sensitive nutrients and important immunological components.

This work was supported by the Canadian Institutes of Health Research and the Ministry of Health and Long-Term Care (MOHLTC). This research project was a key catalyst for a partnership with The Hospital for Sick Children (SickKids), Mount Sinai Hospital, Sunnybrook Health Sciences Centre, the MOHLTC and private sponsorship, which resulted in the creation of the Rogers Hixon Ontario Human Milk Bank launched in 2013. This centre now provides donor milk as a supplement for mother’s milk for all very low birth weight infants born in Ontario.

As we continue this research and our techniques continue to evolve, it is our hope that both short- and long-term outcomes continue to improve for the most vulnerable babies.