The reputed health and nutritional benefits of many foods may be nothing more than a passing fad, but the importance of mothers' milk remains largely undisputed. Certainly, if America's TV diet is any indication, breast-feeding appears to be "in." Past episodes of "thirtysomething" and "Designing Women" have explored the rewards and conflicts experienced by nursing mothers.

The medical community has long supported the nutritional and emotional benefits of breast-feeding to both mother and child. The World Health Organization, UNICEF and the Department of Health and Human Services all promote it as the best method of providing nutrition to an infant.

Yet the number of women in this country who breast-feed their children has declined in recent years. In 1982, 61.9 percent breast-fed their babies upon leaving the hospital; by 1989, that figure had dropped to 52 percent. The drop occurred despite an initiative by the HHS to increase the proportion to 75 percent.

"Ours is basically a bottle-feeding society," says Kathleen Auerbach, editor of the Journal of Human Lactation. "Advertisements for everything from detergent to insurance depict a mother happily bottle-feeding her child," she says.

Efforts to explain the decline point to a combination of factors, including the increasing number of women who return to work soon after the birth of a baby, which complicates the logistics of breast-feeding.

Experts say that bonding occurs with babies who are bottle-fed as well as breast-fed, but some benefits of breast-feeding seem apparent, according to Auerbach. "A breast-feeding mother tends to lose postpartum weight more rapidly," she says.

Recent studies also point to a decreased risk of breast cancer among breast-feeding women later in life, says Auerbach.

Aside from nutritional benefits of mothers' milk, breast-feeding has immunologic advantages that milk substitutes can't provide, according to Frank A. Oski, chairman of the pediatrics department at Johns Hopkins University School of Medicine. Breast-fed babies are less likely to experience early-childhood health problems, he says.

Those who breast-feed for a minimum of three months have a reduced incidence of ear and respiratory infections and gastrointestinal distress, says Oski.

Ironically, it's those mothers whose children who would stand to benefit most from breast-feeding who are least apt to practice it. Lower levels of education and income coincide with reduced rates of breast-feeding. While 70 to 80 percent of college graduates opt to breast-feed their children, less than 15 percent of women with no high-school education do so, according to Oski. Fifty years ago, the opposite was true, he says.

Ruth A. Lawrence, breast-feeding and lactation specialist at the University of Rochester's School of Medicine, attributes the changed attitude to differences in values. "Over the years, we gave the impression that it was modern, mainstream and intelligent to bottle feed," she says.

Lawrence expresses particular concern about the impact of advertising upon less-educated and low-income women.

The number of women returning to work shortly after the birth of a child places limitations on breast-feeding, says Julie Stock, medical-information liaison with La Leche League, a nonprofit organization that promotes breast-feeding.

Continuing to provide a baby with breast milk while working is difficult but not impossible, says Stock, who urges that businesses provide space and time for women to pump their milk during the day as well as refrigeration facilities for storing breast milk.

Upon leaving the hospital, nearly every new mother is handed a free pack containing formula, nipples, bottles and often a toy or rattle bearing the name of the manufacturer.

While some view these giveaways as harmless, others claim the practice sends a subliminal message to new mothers that bottle feeding is not necessarily better, but easier.

At Fairfax Hospital, mothers are given a choice between Enfamil, SMA or Similac brand formula and have the option of choosing an additional packet containing other gift items, according to neonatologist Daniele Huntington.

Huntington sees nothing harmful in the practice. "Most women have made the decision to breast-feed prior to a baby's birth," she says, adding that a lactation consultant is made available to offer instruction or answer questions.

"Studies have shown that most mothers will continue to use the brand of formula they're given upon leaving the hospital," says Janice Mantell, executive director of the Minneapolis-based Action for Corporate Responsibility, an organization that examines company practices related to infant health.

Mantell and others say they are concerned that the health-care system is being used as a vehicle to sell products, in this case, infant formula. Mantell says such practices represent "manipulation by assistance." Such contributions may include incubators, air conditioners, cribs and other goods, she says.

While many hospitals receive donations from formula manufacturers, drug companies and others, Fairfax Hospital's Huntington says its impact upon a woman's decision to breast-feed is negligible.

U.S. infant formula sales are an estimated $1.6 billion a year, according to James Post, a professor of management at Boston University. Post, who has studied the growth of the formula market for over 15 years, points to a recent increase in competition in the U.S. market.

"While the birth rate hasn't jumped dramatically, formula sales have at least tripled over the past 10 years," says Post. He attributes the increase to marketing practices and efforts by formula manufacturers to diversify, adding follow-up formulas for older babies and distinguishing certain formulas as iron-enriched or hypoallergenic, for example.

The "baby-bottle battle," as it has come to be known, reached a new pitch of intensity last fall, when formula advertisements began appearing on television and in popular magazines.

Numerous medical organizations, including the American Academy of Pediatrics and the American Academy of Family Physicians, condemn the practice of direct advertising, calling the decision to bottle feed one that a mother should make following consultation with her doctor.

Sheila Kinkade is a writer in Maine.