Is Breast Best?: Taking on the Breastfeeding Experts and the New High Stakes of Motherhood

2. The Science: Does Breastfeeding Make Smarter, Happier, and Healthier Babies?

21 2 The Science Does Breastfeeding Make Smarter, Happier, and Healthier Babies? AT T H E CO R E of the “breast is best” message is the notion that breastfeeding —the substantive properties of breast milk, the interaction between breastfeeding mother and baby, or some combination of the two— is medically superior to bottle feeding for babies. That is, breastfed babies are physically, cognitively, and emotionally healthier than their bottle-fed counterparts, and their relative well-being can be attributed to one or various dimensions of the breastfeeding process. There is broad disagreement on the extent to which employers and public institutions should make accommodations for breastfeeding, and scientists have not established any consensus on the long-term health effects of breastfeeding for women who lactate. But few in either the medical community or the public, including critics of the rhetorical and political tactics of some more ardent activists, question the biological “fact” that, as the American Academy of Pediatrics (AAP) has argued since 1997, “human milk is uniquely superior for infant feeding.”1 Yet the evidence for breastfeeding’s health benefits is far more equivocal than the AAP implies. Indeed, an analysis of the epidemiological research on breastfeeding—how studies are designed, carried out, interpreted , and communicated among scientists and between medical professionals and the public—indicates that while breastfed babies, on average, do appear to be slightly healthier, the science does not demonstrate compellingly that breast milk or breastfeeding is responsible. Although scientists have recently begun to examine the biological consequences of breastfeeding for women, breastfeeding research has focused overwhelmingly on its potential effects on babies, the consumers of breast milk. In these studies, scientists have looked at the association between different modes of infant feeding and various physical, mental, social, and emotional health outcomes. These include asthma and allergy, bed-wetting, 22 Smarter, Happier, Healthier Babies? various childhood cancers, cardiovascular disease, celiac disease, child abuse, diabetes, diarrhea, eczema, growth pains, leukemia, necrotizing enterocolitis, inflammatory bowel disease, intelligence, mother-infant bonding, obesity, otitis media, postneonatal death, preterm infant health, respiratory infection, sleep-related breathing disorders, social mobility, stereoacuity, stress, sudden infant death syndrome (SIDS), and urinary tract infection. PubMed, a database of medical research maintained by the National Library of Medicine, indicates that 1,155 articles with “breastfeeding” or “breast-feeding” in the title or abstract were published in 2009 alone. The scientific literature is voluminous , and I do not intend that this chapter be a comprehensive review. Rather, I concentrate on the health outcomes for babies that have generated the most attention in scientific journals with relatively high “impact factors,” or rates of citation. I also incorporate the evidence cited by the National Breastfeeding Awareness Campaign (NBAC), sponsored by the U.S. Department of Health and Human Services between 2004 and 2006, and articles in journals determined to contain “the best evidence relating to clinical pediatric practice.”2 I do not include material from journals devoted specifically to breastfeeding, including Breastfeeding Medicine, International Breastfeeding Journal, and the Journal of Human Lactation. All these are peer reviewed and have editorial boards composed of research scientists, but their editorial policies make clear that each journal’s mission is to promote breastfeeding.3 I offer a plausible rival explanation for breastfeeding’s benefits: that behavior associated with breastfeeding, not breastfeeding per se, explains any relationship between breastfeeding and better health. I argue that methodological and interpretive problems are pervasive at every step of the research process, from the design of the studies to the communication of their results; that as is often said, correlation does not equal causation; and that except in the case of gastrointestinal infections, the biological mechanisms by which breastfeeding promotes better health have not been demonstrated. In short, I contend that the unfounded certainty about breastfeeding’s benefits in both scientific and popular culture is rooted in the discourse of breastfeeding research. Observational Research The success of epidemiological studies depends not on their ability to explain how diseases are acquired and controlled, ostensibly the mission of epidemiology, but on their establishment of a statistical relationship Smarter, Happier, Healthier Babies? 23 between a variable or a set of variables, such as obesity or the consumption of dark chocolate, and a particular outcome, such as heart disease or high blood pressure. Variables linked with disease, such as high cholesterol or residency in a highly polluted area, are termed “risk factors.” In the past decade, epidemiological research...