However, many women ignore the advice, and a new study finds that poor women are more likely turn to formula early than better-educated and richer women.
The findings may sound counterintuitive -- poor women are more likely to choose formula, even though it isn't free -- but they do accurately reflect trends of the last several decades, says Dr. Ruth A. Lawrence, a professor of pediatrics at the University of Rochester.
Despite its decline in popularity among some women, breast-feeding remains the best way to feed an infant, she says: "The human brain will double in size in the first year of life. The nutrition we provide should be the best stuff there is for brain growth, and that's human milk."
Researchers at the Centers for Disease Control and Prevention (CDC) analyzed surveys of about 4,000 American women, conducted from 1988 to 1994. The results appear in the July issue of the American Journal of Public Health.
Nearly half of women reported exclusively breast-feeding their babies during the first few months after birth, but 90 percent turned to other sources of food at six months.
Breast-feeding rates were especially low among black women and poor women. A study published last year in the journal Pediatrics found black women are much less likely to breast-feed than white women.
However, three groups of women were more likely to breast-feed exclusively in the first few months of the lives of their babies: those who graduated from college (82 percent), those from a family with a head of household who graduated from college (80 percent), and those with an income well above the poverty level (75 percent). However, even most of those women failed to continue breast-feeding exclusively until their babies were six months old.
The reasons for the rarity of breast-feeding aren't clear, says study co-author Dr. Ruowei Li, a medical epidemiologist with the CDC. "The mothers may think breast-feeding interferes with their lifestyle habits and is inconvenient," she says.
The discrepancy "could be deeply rooted in a culture of belief that mothers cannot provide sufficient nutrition to their babies," she adds.
The popularity of breast-feeding has swung up and down since infant formula was introduced about 70 years ago, Lawrence says.
"The well-educated woman led the march to the bottle, and we saw the first beginning dips in breast-feeding," Lawrence says, as poorer women continued to breast-feed.
However, the situation reversed a few decades later, as the well-educated women began to learn about the benefits of breast-feeding. "They suddenly realized they'd made a mistake," she says. "They realized that [formula-feeding] wasn't the best thing, and they ought to be doing the best thing."
Poorer women, meanwhile, jumped on the formula bandwagon, she says. However, breast-feeding remains "perfect nutrition," she says. "It's specifically engineered for the human infant."
Studies show that breast-feeding "lowers the rates of infectious disease and chronic disease, ear infections, diarrhea and obesity," Li says.
Unlike formula, human milk is stocked with disease-fighting antibodies as well as fatty acids, cholesterol and other building blocks of healthy development.
Education efforts are an ideal way to convince women to breast-feed, Li says. "It's really a public effort, involving health professionals, federal agencies and private organizations," she says. "Multifaceted intervention will make it better."
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