There are numerous studies which suggest that breast-feeding can put a child at lower risk for a whole host of diseases and conditions, including sudden infant death syndrome, respiratory infections, meningitis, pneumonia, diarrhea, ear infections, asthma, diabetes, autoimmune diseases (such as Crohn's) and leukemia [source: Rabin]. Breast-fed babies have a lower risk of obesity than formula-fed babies [source: Rabin]. In fact, the American Academy of Pediatrics believes that the United States could save $3.6 billion in annual health care costs if more women breast-fed because the babies would require substantially less medical care [source: Harmon]. Breast milk derives these powers because it's full of antibodies, hormones, neuropeptides and natural opioids that formulas can't replicate.
And not only is breast-feeding believed to be good for the baby, it provides benefits to the mother as well. It helps a woman heal quickly after childbirth by causing the uterus to return to normal size and reducing bleeding. Women who breast-feed have a lower risk of heart attack, stroke, adult-onset diabetes and osteoporosis [source: Rabin]. Breast-feeding can also reduce a woman's risk of ovarian cancer and breast cancer; one study suggested that women with a family history of breast cancer could reduce their risk level, via breast-feeding, to equal that of a woman who had no family history of the cancer [source: University of North Carolina School of Medicine].
The studies on breast-feeding's benefits are so numerous that legislators have considered putting warning labels on formula packaging. But in 2009, Hanna Rosin published a piece in "The Atlantic" that dared to suggest that breast milk was not the magic elixir that its proponents claimed (the negative reaction Rosin's piece received demonstrated just how seriously the mommy wars are when it comes to the breast).
Rosin pointed out that studies regarding breast-feeding were inconsistent, and those that tout breast milk's benefits can only show an associative relationship, not a causal relationship. In other words, these studies can't say that breast-feeding caused the beneficial outcomes, only that these babies that were breast-fed also experienced them. These outcomes could be due to some other factor that breast-feeding mothers have in common. Since women who breast-feed in the U.S. tend to be older, more educated and have higher incomes than women who don't, it's possible these women are able to confer advantages upon their children that other women can't.
Additionally, studies about breast-feeding can be flawed from the start; it's unethical to tell a woman what to feed her baby, so researchers rely on observational studies with self-selecting participants. Still, there's one researcher who's managed to design some scientifically rigorous tests about breast-feeding.