A Note from the Author:  The Science of Mom, is about how science can help us make smart parenting decisions, particularly in the first year of a baby’s life. It focuses on some of the major questions of infancy, including those of newborn health, sleep, and feeding. There are lots of controversies among these topics, and parents often debate what is right. Sometimes, science can help us settle those debates. Other times, the science is still evolving, and the complexities of families leave plenty of room for us to make different choices. The following excerpt is the start of Chapter 5, entitled “Milk and Motherhood: Breast Milk, Formula, and Feeding in the Real World.” The remainder of the chapter delves into the science of both the benefits of and very real challenges to breastfeeding. It was one of the most challenging chapters for me to research and write, but it is also one of which I’m most proud.

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When Cee was handed to me just after birth, she came screaming and red-faced, with her eyes squinted shut. I said hello to her, and she stopped crying, opened her eyes wide, and gazed alertly into mine. And then, within a couple of minutes, she started moving her cheek against my breast, rooting for milk. I opened the hospital gown and held her clumsily, trying to remember the holds I’d practiced with a baby doll in my two hours of breastfeeding class a month before. A nurse confidently arranged a pillow under my arms and guided my hands in place. Cee did all the rest. She latched on and started nursing with the confidence of a pro. It was good that her instincts were so strong, because I’m not sure mine had kicked in yet.

I was determined to get everything right about motherhood, and feeding was no exception. I always planned to breastfeed, and between the two of us, Cee and I figured it out pretty quickly. After the first couple of weeks of nipple soreness and constant nursing, we settled into pleasant feeding routines. I loved this time with her, and it was empowering to know that my body could make this perfect food that could nourish her so completely. Breastfeeding was a big part of my identity as a new mother, and it was a source of pride. I relished the approval from my pediatrician, family, and friends, and I enjoyed the supportive glances from strangers. (I know many moms experience an overt lack of support when they breastfeed in public, so I consider myself lucky that I never did.) Because my experience was so positive, it was easy for me to be a little judgmental of women who didn’t breastfeed, given the long list of benefits for both mother and baby.

Three years later, my brother and sister-in-law, Jordan and Cheryl Green, welcomed their own baby girl, Amy Bell. Cheryl planned to breastfeed and, like me, was surrounded by support, from Jordan, her grandmother, and her friends, among them lots of moms experienced with breastfeeding.¹ But beginning at the hospital, Cheryl’s plans quickly unraveled. Amy Bell struggled to latch on correctly, and although she appeared to be feeding, her weight was dropping rapidly. Within her first couple of days of life, she lost 12% of her birth weight, and a lactation consultant urged Cheryl and Jordan to supplement with formula. For the next three weeks, Cheryl kept up a labor-intensive cycle of attempting to breastfeed, pumping, and supplementing with formula. Everyone–nurses, lactation consultants, and her friends–told her to keep trying, that it took time and practice, but still, Amy Bell didn’t latch on, and very little milk came through the pump. Cheryl was scheduled to return to work at four weeks postpartum, and she didn’t know how she would keep up these efforts on the job. Reluctantly, she and Jordan began exclusively feeding formula to Amy Bell.

Cheryl says she still feels a little guilty about not breastfeeding for longer, and she wonders if she missed out on a special bond with Amy Bell. But, she told me, it was also really helpful to be able to share feeding responsibilities with Jordan as they both learned the routines of new parenthood. For Jordan’s part, he had been very attached to the idea of Cheryl breastfeeding their daughter. He grew up around breastfeeding, and he saw it as the normative and natural way for babies to be fed. But Jordan told me that he now appreciates that feeding, like all of parenting, is a “balance between ideals and practical realities.” Thinking about Amy Bell, he said: “Now that I’ve watched her grow into an active, alert, engaged, and advanced baby, I feel confident that her needs are being met.”²

Jordan is only bragging a little when he says that his daughter is advanced. Amy Bell is now 10 months old. It seems like she’s hit nearly every milestone a little ahead of schedule, and she’s never really been sick.³ She and Cee are both beloved in our family, and nobody would ever think to wonder whether they’d been fed differently as babies.

Comparing my and Cheryl’s breastfeeding stories, however, there is an impulse to call one a success and one a failure. That haunted me as I started working on this chapter. Cheryl’s experience was riddled with challenges that I never had to face, and she tried harder than I ever had to. Her story of struggling to make enough milk is just as common as my happy story of breastfeeding for two years. And by most reasonable measures, Amy Bell and Cee are both big successes: They’re happy, healthy, and well-nourished children, and both of our families have found our own ways of adjusting to new parenthood.

But for new mothers, it can be hard to find that perspective. Beginning in pregnancy (and often before), we all hear the same message: good mothers breastfeed–it’s one of the most important gifts you can give your baby. This message translates into tremendous pressure to breastfeed, and we’re quick to judge ourselves and each other if it doesn’t work out. It is because of this pressure and judgment that how we feed our babies has become one of the battles in the “mommy wars.” This is an unfortunate way to talk about feeding, one of the most important ways we care for our babies, whether by breast or by bottle.

Breastfeeding and its role in modern parenting is in part a story about science: how science has paved the way for good substitutes for breast milk while at the same time revealing the intricacies of breast milk, which no substitute is likely to replicate. But it’s also about how science is translated to real life. How is it molded into public health messages intended to alter women’s behavior? And what happens if breastfeeding, which should be the most natural way to feed babies, just doesn’t work?

A Short History of the Science of Infant Feeding

The ability to make milk to feed our young is what makes us mammals, and as humans, we evolved to produce a milk uniquely suited to meeting the nutritional and immunological needs of human babies. Breastfeeding is the biological norm, and it is how the majority of young infants have been fed throughout most of the history of our species.

There have always been substitutes for breastfeeding, though, and following their history is a fascinating way to follow the science of milk. For a long time, there was no science to guide infant feeding strategies; mothers and other caregivers just pieced together what they could. If a mother didn’t make enough milk, had to work away from home, or died in childbirth, or if a baby had an oral handicap that impeded nursing, then other options were needed. Sometimes this meant another lactating woman, maybe a family member or friend, would help nurse the baby, and sometimes a wet nurse was hired expressly for this purpose. Records of wet nurses go back at least as far as the third or fourth century BC.⁴

But if human milk wasn’t available, substitutes were used. Since wet nurses were being paid to feed another woman’s baby, sometimes their own babies would be denied enough milk from their moms and would need these substitutes.⁵ Almost as soon as cows and other dairy animals were domesticated, their milk was used for infants, sometimes placing babies directly on the teat to nurse.⁶ Infant feeding vessels have been found in children’s graves throughout the Roman Empire, dating back to 4000 BC.⁷ By the 1400s, soon after the invention of the printing press, printed books offered advice and recipes for homemade supplements called pap or panada. These usually contained a cooked combination of several ingredients, including cow’s or goat’s milk, bread crumbs, flour, meat broth, honey, egg, and sometimes even wine or beer.⁸ These concoctions could be used as the primary food for a baby or as a supplement to breast milk. Cross-cultural historical records indicate that two-thirds of preindustrialized societies introduced some solid foods to babies before 6 months of age, sometimes as early as a few weeks of life.⁹

Throughout most of history, it was probably self-evident that substitutes were inferior to breast milk and often resulted in illness. Ironically, this situation became especially dire in the eighteenth and nineteenth centuries, when it was a common belief that boiling cow’s milk made it less nutritious. Raw milk was usually swimming in bacteria by the time it traveled, unrefrigerated, from farm to baby.¹⁰ During this time, babies fed breast milk substitutes suffered and died disproportionately from diarrhea, particularly during the summer months. In the late 1800s, nearly all bottle-fed infants in New York City orphanages died.¹¹

Enter science. In the late 1800s, Louis Pasteur’s work showed that bacteria caused disease and that they could be killed with pasteurization. Water chlorination and modern sewage systems meant clean water for feeding and for cleaning bottles and nipples. By the early 1900s, the availability of kitchen iceboxes and canned evaporated milk meant that relatively safe formulas could be made at home.¹²

The study of nutrition was also exploding. By the late 1800s, scientists understood that not all milks are alike. Cow’s milk has more protein and less sugar than human milk, so scientists and pediatricians began recommending recipes meant to be a closer match. A common recipe that could be made at home called for one 13-ounce can of evaporated cow’s milk, 19 ounces of water, and 1 ounce of Karo corn syrup. Scurvy and rickets were common problems, but by the 1920s, supplementation with fruit or vegetable juice and cod liver oil decreased the incidence of these vitamin deficiency diseases.¹³

As science revealed more and more about nutrition, the recommended formula recipes grew more complex. Food companies stepped in to offer commercial products, relieving hospitals, institutions, and moms of having to make their own and creating a huge, profitable market. By the 1950s, commercial formulas had gained popularity and began to replace homemade recipes.¹⁴ These products were, for the most part, nutritionally adequate, clean, and consistent. For the first time in human history, babies could be exclusively fed a breast milk substitute without a noticeable risk to their health. Most parents and pediatricians assumed that formula was just as good as, if not better (being more “scientific”) than, breast milk. Mothers increasingly turned to doctors for advice, and doctors recommended that breastfeeding moms feed their infants on a schedule, typically every four hours. If that didn’t seem to satisfy the baby, then supplementation with formula was needed.¹⁵

Other societal changes made formula feeding the preferred choice for modern women. By the mid-1900s, most women were giving birth in hospitals, where they were separated from their babies soon after birth and allowed only brief, scheduled visits for feeding, making it difficult to establish breastfeeding.¹⁶ But women were also looking to break free of their duties as full-time mother and housewife. Particularly during World War II, formula allowed women to fill important jobs in the workforce, and after the war, they didn’t want to give up their careers.¹⁷ Breastfeeding went from necessary to optional to out of style. By 1970, it had reached an all-time low: only one in four infants were breastfed past one week of age.¹⁸

But around the same time, women began fighting for more freedom from medical authority in childbirth and parenting, and a renewed appreciation for breastfeeding was part of this movement.¹⁹ Scientists, meanwhile, were beginning to take a closer look at breast milk and were finding that it was much more than just a collection of nutrients. While formulas based on cow’s milk or soy can be made to contain a similar amount of protein, fat, and carbohydrate, these nutrients are of better quality and more easily digested in breast milk than in formulas.²⁰ Breast milk also provides a dynamic suite of immunological proteins, growth factors, stem cells, digestive enzymes, hormones, and prebiotics.²¹ We can now appreciate that breast milk probably evolved to include many of these components because they’re good for babies, and investigating health outcomes in breastfed and formula-fed babies has been a very active area of research for the past several decades.

The history of breast milk substitutes is a reminder that they’ve always been needed, but only in very recent human history has science allowed for a safe alternative. That there is even a debate over breast versus bottle is made possible by science. It’s also fueled by the science examining potential benefits of breastfeeding. This science, however, is difficult to do and even harder to interpret in a meaningful way.

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Read Brain, Child’s exclusive Q&A with Alice Callahan, PhD.

Alice Callahan, PhD is a former research scientist and now a writer and teacher. You can find more of her writing about parenting and science at her blog, Science of Mom.

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