A version of this story was originally published on October 17, 2017. It has been updated.
It's undeniable that breast milk is downright incredible. From the way it adapts to meet your baby's needs at different times to its immune-boosting qualities, breast milk deserves all the applause.
“It is incredible that your body can provide such a magical substance for your baby," says Diana Spalding, CNM, a Motherly advisor and midwife. “It's just more proof that we know how to mother our children intuitively." Here are more ways the breast milk science continues to amaze us.
Learn more about the science behind why breast milk is magic.
1. Mothers' breast milk varies based on the child's sex
Studies have shown that the breast milk mamas produce varies in significant ways based on whether they are feeding a boy or girl. Specifically, the milk produced for female offspring (across a number of different mammal groups, including humans) tends to be lower in fat and protein than that created for males.
But making this even more remarkable are the adaptations in milk for children's sexes in different cultures: As a 2012 study published in Nature found, impoverished mothers in Kenya produced fattier, higher-quality milk for daughters versus sons—which led researchers to hypothesize this is because girls stand a better chance at raising their family's profile through beneficial marriages.
2. The composition of breast milk changes as baby ages
As any mom who has witnessed the first days of colostrum give way to bags and bags of expressed milk can attest, babies' nutritional needs change as they grow—and breast milk keeps up. And these changes to breast milk continue as babies age: According to a study published in the journal Pediatrics, the fat and energy contents in milk expressed from moms who have been lactating for more than one year were “significantly increased" than the fat and energy contents in milk from moms breastfeeding younger babies.
3. Breast milk adapts when baby's sick to provide stronger antibodies
When a nursing baby comes down with a cold, research shows the numbers of leukocytes in the mother's breast milk spikes. Even more incredible to think about is the theory about how this information is communicated from baby to mama: Although research is limited, there are some strong scientific suggestions that backwash from baby's mouth through mother's nipple can carry signals that indicate the need for more antibodies.
4. Breastfeeding reduces rates of certain ailments
Studies show breastfed infants grow up to experience lower rates of asthma and allergies, and the reason why may be because the short-chain fatty acids found in breast milk are uniquely able to line infants' colons and lead to stronger immune responses. And that's not to mention that a study suggested the human proteins found in breast milk may aid in battling cancer.
5. Human breast milk is especially designed for our brainy babies
Although all mammal mamas produce oligosaccharides in their breast milk, human mothers are super oligosaccharides producers—with some 200+ varieties of human milk oligosaccharides (HMOs). The amazing part? Our babies can't even digest these simple sugars.
But while they can't directly digest oligosaccharides, research that has been in development for years shows the HMOs promote productivity in infants' guts and, in turn, helps them digest protein and other forms of energy more effectively. Following that reasoning, evolutionary scientists believe humans are (totally subconsciously) investing the energy into HMO production to give our brainy babies a bigger boost.
6. Breast milk during nighttime nursing sessions promotes infant sleep
Good news for any mama ready to get her baby back to sleep ASAP after a nighttime feed: Breast milk produced in the twilight hours has higher levels of sleep-promoting nucleotides than milk expressed during the day. This finding led researchers to suggest pumping moms offer milk expressed during certain times of the day to their babies at that same time of day—because the wonders of breast milk are really only just being revealed.
While breastfeeding may not be an easy journey, it sure is comforting to remember that not only are you helping your baby grow—but you're also working some magic while doing it.