Did You Know? Research Says Breast Milk is Tailored to the Sex of Your Baby

Breast milk self-tailors depending on the sex of your baby. Just when you thought your breast milk couldn’t be any more amazing, new research has come out suggesting that it self-tailors to the sex of your baby.

Yes, that’s right – baby boys and baby girls get different breast milk.

As if we didn’t already know that our breast milk changes as our baby’s needs change, we also know that our breast milk changes based on our baby’s sex too.

Research has found that human breast milk not only varies between mothers in the same and different populations, and studies show the chemical and nutritional makeup of a breastfeeding mother depends on the gender of her breast-feeding baby.

Related: Study: Immune Cells Found in Breast Milk Make It Irreplaceable

Another specific study done in 2018 looked at the breastmilk of 48 mothers. All the mothers were breast-feeding their babies; 24 were nursing baby boys and 24 were nearsing baby girls. The researchers in the study looked at the makeup of 5 ml of breast milk collected from each of the mothers. They analyzed the milk for calcium, carbohydrates, proteins and lips contents. They found significant differences in the lipid and calcium concentrations of the breast milk, and the scientists concluded that breast milk is even more dynamic and personalized than previously thought. They also concluded that there’s no specific formula when it comes to mimicking breast milk, as the contents of breast milk are clearly not fixed.

Breast Is Best At Making It Perfect

Other studies have been inspired by previous research that showed some mammals produce milk tailored for the specific sex of their offspring.  For example, macaque monkeys produce milk richer in fats and gross energy for their male offspring, but produce greater quantities of milk that is also higher in calcium for their female offspring. There have been similar results in human studies as well.

To see if this theory applied to humans, researchers used data that had been collected by the National Longitudinal Study of Adolescent Health — a large, long-term behavioural and medical study of young Americans. For the study, participants were interviewed at four different times in adolescence.

Researchers looked specifically at the data that had been collected from twins: same-sex twins and opposite-sex twins, both breastfed and non-breastfed. They found that breastfed same-sex twins were taller and heavier through adolescence and early adulthood than breastfed opposite-sex twins who, theoretically, received breast milk that could not be simultaneously tailored for the different sexes.

Related: The Colors of the Breast Milk Rainbow, and What They Mean

By contrast, same-sex twins that were never breastfed were shorter and lighter than opposite-sex twins that were not breastfed. What the researchers then concluded was that the moms of twins who were breastfed were making milk specifically for each twin, and they believe the sex of each twin played a pivotal role in that milk production.

Why is this important? 

Researchers on both sides of the breastmilk/formula debate find it important because it supports their position. For those proponents of formula, the belief is that knowing there are differences in breast milk that appear to be gender-based, better formulas can be created to tailor to those individual needs for each. Those who believe breast milk is the best option for babies obviously cite the fact that the milk a mother produces is already tailored specifically to her own child, right down to his or her gender-based needs, and no formula could ever mimic that.

And while we’ve always believed breast is best, we do know that not every mother can breast-feed and does use formula. This information could make formula more specific for the age, stage and gender-based needs of babies, and make the nutrition they get from the formula closer to what they’d get if they were to get breast milk.

Regardless, it shows the incredible flexibility of not just a mother to produce specialized milk, but babies too, as it’s their saliva that talks to a mama’s body and gives directions that only could come through that mama-baby bond. Not to mention, some moms choose to nurse their babies because they believe formula is just as good or better even than their own milk. The marketing of formula companies through the years has convinced them of that, and while again, we believe there is a place for formula for mothers who cannot nurse, maybe some moms who weren’t super confident in themselves before learning about the magic of their breast milk may change their minds!


One thought on “Did You Know? Research Says Breast Milk is Tailored to the Sex of Your Baby”

  1. There are mothers who assign a certain breast to each twin. That could also be a variable. As could gestational age at birth (prematurity). Some people say that race plays a role in size during various stages of adolescence. Some say that is also influenced by socio-economic factors. Too many variables to make a simple conclusion.

    I question adolescents breastfed as infants being heavier than those who were formula fed. This does not agree with obesity studies, just off the top of my head.

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