A study in the February 2009 issue of Nutritional Neuroscience, by researches in Spain, concluded that the levels of substance called nucleotides, that may influence sleep patterns in infants, vary in breast milk throughout the day. The title of the study is "The possible role of human milk nucleotides as sleep inducers," and the formal conclusion is that these nucleotides "showed increased concentrations at night and may, therefore, be involved in inducing hypnotic action in the infant."
While this in an interesting bit of information, breastfeeding mothers have always known through observation that expressed breast milk often changes in composition throughout the day, this being only one component of that change. Other substances are also shown to vary in breast milk throughout the day. This is just one more clue that breast milk is a wonderfully dynamic source of nutrition for babies that will never be duplicated adequately by formula makers, despite their claims.
What concerns me about this study is that is seems to have spawned a great deal of incredibly irresponsible news coverage about the need to time the use of stored breast milk, making claims that are nowhere in the study.
Most of this is the fault of the lead study author, Cristina L. Sánchez, researcher at the Chrononutrition Lab at the University of Extremadura, Spain of the study who quoted all over internet news outlets as saying "It is a mistake for the mother to express the milk at a certain time and then store it and feed it to the baby at a different time,” as well as “You wouldn’t give ayone a coffee at night, and the same is true of milk. It has day-specific ingredients that stimulate activity in the infant, and other night-time components that help the baby to rest.” The use of idiotic headlines about this study such as "Mistake to express breast milk to feed baby later," which clearly mean something entirely different are also a serious concern.
I have read the study carefully, and nowhere does it explore *any* of the claims the researcher has irresponsibly attributed to her work. It does not explore the presence of "day-specific ingredients that stimulate activity in the infant" and it certainly does not study the sleep patterns or well-being of infants who are fed expressed breast milk at various times of day as compared to when they have been expressed.
This researcher has taken a huge leap away from any sort of scientific analysis following the publication of her work, and should be both embarrassed and called to task for her behavior and misinformation. She is severely overstating the importance of her work and doing breastfeeding mothers and babies a huge disservice.
The last thing nursing mothers need, especially harried working mothers who are doing their baby the loving service of expressing milk for the times when they are part, is to be stressed out by the notion that they are somehow harming their children if not pumping milk at the exact moment of the day their child will be consuming it. This has never been shown to be the case, and certainly not as a result of this study.
Yes, there may be some measure of common sense that would suggest that marking the time of pumped milk and when possible and practical to line up morning, midday, evening and/or nighttime feeds within some sort of close proximity, because yes, there are some differences in milk. But to state that a nursing mother is giving our baby a coffee at night is using milk expressed in the morning is simply unsubstantiated and a bit ridiculous.
Shame on the researcher who took a perfectly responsible study and tried to turn it into something it was not to gain notoriety. And further shame on the irresponsible outlets who reported this information with poorly written headlines or weakly extrapolated claims to get readers.
If a nursing mother is producing and expressing enough milk to supply her baby's needs when they are separated, give that woman the medal she deserves. If it is convenient and possible for a caregiver to use that milk at approximately the same times that it was pumped, great… it certainly can't hurt. But adding this to the vast list of things for mothers to stress over is simply not necessary. And under no circumstances would formula be preferable to breast milk simply because it was pumped at a different time of day than the feeding. Keep nursing and feeding your expressed milk to your babies, mamas… you are doing just great, whatever time of day.
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