While the health benefits of breast feeding baby are well known, a new study published in BioMed Central's open access journal BMC Pediatrics finds that, for very low birth weight (VLBW) babies, a small amount of fortification can improve growth rates without sacrificing the benefits associated with mother's milk.

Human milk provides babies with exactly the right nutrients for growth and also helps protect against infections and diseases. Breast fed babies are less likely to have diarrhea or vomiting, they have fewer chest and ear infections, and long term are less likely to become obese or develop eczema. However, in hospitals human milk is also associated with slower growth in the first few months of life compared to formula-fed infants.

Researchers from the University of Iowa looked at records of births between 2003 and 2005 in order to compare birth weights, diet, and weight when the baby was discharged from hospital. The majority of VLBW infants (less than 1250g), although small, were the appropriate size for their gestational age (an average of 27 weeks), and stayed in hospital for two to three months after birth. Babies were fed either mother's milk, donor (pasteurized human) milk, or formula, all of which were supplemented as required to improve protein levels and total calories.

The results showed that, while the growth of all the babies was within normal limits, the babies fed more than 75% human milk grew more slowly than babies fed with less than 75% human milk. This difference in growth was even more pronounced for babies fed on donor, rather than mother's, milk.

Dr Tarah Colaizy, who led this study, explained, "Human milk offers many benefits for VLBW infants, and should of course be the default diet for all such infants. However our babies on average became smaller for gestational age between birth and discharge from hospital. We recommend that special attention is given to ensure that the amount protein and calories consumed is necessary to provide the benefits of a human milk diet without sacrificing growth."

So, while breast milk is definitely still best, very small babies may need a little help.