Previous research has shown the macronutrients in milk produced by mothers who give birth prematurely differ from those in milk of mothers of full-term infants. This suggests the mother’s body attempts to compensate for the nutrition her premature baby did not get in the womb.
This latest study on human milk by researchers in Denmark and Ireland showed that not only does the micronutrient (metabolite) makeup of human milk differ for mothers of pre- and full- term infants, the differences also last only five to seven weeks, irrespective of the infant’s developmental stage.
Pre-term boost is limited
“For extremely early pre-term infants born at a gestational age of, e.g., 24 weeks, these findings suggest that mother’s milk becomes equivalent to mature milk for term infants by the time the infant reaches about 29 weeks post-menstrual age,” wrote the researchers in the study.
“This is a significant finding concerning a period in which the infant still requires advanced nutritional support to maintain its growth and long-term developmental requirements. Clinical metabolomics could potentially be advantageous to determine when milk metabolites levels become inadequate due to maturation of milk, if causal relationships between milk metabolites and infant growth parameters can be established,” they added.
The researchers noted previous studies have shown that human milk has significant health benefits for pre-term infants. But they suggest consumption of inadequately nutritious milk by pre-term infants could lead to insufficient weight gain and nutrition defects.
Help providing optimum nutrition
“If we are able to demonstrate a connection between the milk's nutrient content and the child's development, then the analysis method may be used to determine whether the milk is sufficiently rich in nutrients – and thus we can help vulnerable, premature infants by providing the optimum nutrition which they cannot achieve solely from breast milk,” said study author Ulrik Kræmer Sundekilde, a postdoctoral researcher at Aarhus University in Denmark.
“We do not yet know the nutritional importance of all metabolites, and as premature infants have other and more specialised nutritional needs it may constitute a challenge that they are actually fed milk that they are not yet fully developed to digest. Particularly during a period that is extremely important for their future growth and development,” he added.
Sundekilde and the other researchers called for further studies, including developmental studies of children and analysis of the breast milk they received.
The study, published in the journal Nutrients, analysed milk from 15 pre-term mothers and 30 full-term mothers in Ireland.
Researchers used nuclear magnetic resonance spectroscopy to analyse the nutritional make-up of the samples, which were found to change significantly following birth.
“Levels of fucosyl moieties, N-acetylneuraminic acid, N-acetylglucosamine, 3’-sialyllactose, 6’-sialyllactose, 2’-fucosyllactose, citric acid, choline, and creatinine decreased with time postpartum […] while levels of 3-FL, lacto-N-difucohexaose I (LNDFH I), butyrate, caprylate, caprate, lactic acid, valine, leucine, alanine, glutamate, and pantothenate increased with time postpartum,” the researchers wrote of pre-term milk samples.
They also found the make-up of full-term milk changed over time.
“Several milk metabolites were found to be present in significantly different concentration in colostrum, transitional, and mature milk. Fucosylated oligosaccharides, and also components of oligosaccharides (Fucose, N-acetylneuraminic acid, N-acetylglucosamine), were found at the highest levels in colostrum, and levels decreased in mature milk samples.
“Moreover, levels of valine, leucine, pantothenate, citric acid, lactic acid, betaine and creatinine were higher in colostrum and transitional milk compared with mature HM, and levels of glutamate, butyrate, caprylate, and caprate were higher in mature HM compared with colostrum and transitional milk.
"The level of β-hydroxybutyrate was found to be independent of milk maturity in full-term HM,” the authors added.
Published online ahead of print, doi: 10.3390/nu8050304
“The Effect of Gestational and Lactational Age on the Human Milk Metabolome”
Authors: Sundekilde, U K; Downey, E; O’Mahony, J A; O’Shea 3, C-A; Ryan, C A; Kelly, A L; Bertram, H C