Breastmilk is far more than just nutrition. It’s a living substance, containing many immune protective factors which help protect babies against infection. In fact, it contains about 800 different proteins which are important for various processes (e.g. brain and immune development).
Breastmilk changes during the course of a breastfeed, and also changes from day one, to day seven, to day 30, and so on. A mother’s breastmilk is made as required, to meet the needs of her baby, depending on her baby’s age at the time. For example, during weaning, a mother’s breastmilk has an increased concentration of immune protective factors to give the baby a final dose of immune protection before weaning is complete.
Also, remarkably, the breastmilk made by the mother of a premature baby has different concentrations of various substances to suit her baby’s special needs.
Preterm Breastmilk Differences
So how does preterm breastmilk differ from term breastmilk, and why are the differences important?
Preterm Breastmilk Has A Higher Concentration Of Immune Protective Factors
The breastmilk a mother makes for a premature baby is different from the milk she would make if her baby were born full term. It contains higher levels of protein, DHA, magnesium and iron, and higher concentrations of immune protective factors.
A recent study found that preterm breastmilk contains significantly higher concentrations of some immune proteins (e.g. lysozyme, β defensins 1 and soluble CD14 receptor) than term breastmilk does. The study also found that more than 60% of the mothers’ colostrum protein content was for immunological and bacteria defence purposes (rather than for a nutritional purpose).
But why are these differences between preterm and full term breastmilk important?
Premature Babies Are At Risk Of Various Health Complications
The differences in preterm breastmilk are important because premature babies are at increased risk of some serious health complications.
For example, premature babies are at increased risk of sepsis (blood infection) and necrotising enterocolitis (a potentially fatal complication of prematurity whereby part of the bowel dies). Lack of breastmilk (or formula feeding) increases the risk of these health complications in premature babies, partly due to the lack of immune protective factors contained in breastmilk.
Premature babies might also need early supplementation because they lack the various nutrient stores of a term baby. For this reason, breastmilk contains higher concentrations of magnesium and iron. Very premature babies might need their mother’s milk fortified, to provide more minerals and protein for adequate growth.
Formula feeding is associated with lower long term IQ outcomes in premature babies, when compared with breastfed premature babies. This could be due partly to the lack of long chain polyunsaturated fatty acids, including DHA, in formula and might be a reason why preterm breastmilk contains higher concentrations of DHA. Even if formula has added DHA, it comes from a non-human source and cannot function in the same way.
Breastmilk is a remarkable living substance, and science is only beginning to unravel its infinite complexities.