From Dairy Farms to Nurseries: Taking A Closer Look at Breast Milk Production

Consuming countless vitamins, nutrients, and up to 10 billion live immune cells a day, there's no denying it: breastfed babies, of any mammalian species, get some of the most incredible nutrition around. But could it be that gender of your infant determines how much milk they're getting? In a recent study, published on PLOS One, on female lactating cows by Katie Hinde and several of her associates, it's been shown that the sex of the fetus, as well as other factors in utero, plays a large part in how much milk the mother produces for her young, as well as how much milk the mother will produce for any future pregnancies.

After studying over 2.39 million lactation records from 1.49 million dairy cows, it's been shown that heifers who, during their first pregnancy, gave birth to a daughter produced 1.6 percent more milk than they would have for a son. Interestingly enough, this bump up in production from the first female pregnancy was maintained for any future pregnancies, but the heifers who first gave birth to a son did not receive as high of a raise in milk production. Because on the dairy farms the female calves are taken away from their mothers soon after birth, it was noted that the overall boost in milk production must have come while the calf was in utero.

Other studies have shown that human mothers, in a similar sense, also produce more milk for their first born daughters than their sons. One reason for this could be the hormone estrogen, which is more abundant in the female fetus as well as the mother and could correlate to the boost in milk production. There are also many other physiological and hormonal factors that are involved in the production and nutrient content of breast milk, including the mother's gut bacteria and environmental exposure to pollution or toxins. Studies have shown that milk produced for a week old female newborn can be much different, in terms of nutrient and bacterial content as well as hormonal levels, than the breast milk produced for a ten month old male baby. It all depends on the individual needs and demands of the child in question.

Overall, the more time passes the more we realize that the differences between other species and ourselves, especially concerning our young, really aren't as glaring as we once thought. Being one of the most universal forms of nutrition, breast feeding has proven itself again and again to be incredibly adaptive and specific to the mother and child, whether they are human or not. The amazing specifications of breast milk will continue to be explored and studied as scientists yearn to understand the subtle physiological intricacies and factors that are involved in producing the most ancient life giving substance there is.