Despite proven health benefits, breast-feeding has not taken hold at desired levels in the United States, especially as the sole source of nutrition during the first six months of life, doctors said on Monday.

The American Academy of Pediatrics issued an updated statement on the practice - which it has long backed - in an effort to get more women to breast-feed longer for the benefit of infant and mother.

“The most important thing about it is that it continues to recommend exclusive breast-feeding for the first six months of life, and then continuing it for the next six months while weaning foods are being added,” said Ruth Lawrence, a physician at the University of Rochester Medical School who helped draft the statement.

She said all of the health benefit references have been updated to make an even stronger case for breast-feeding.

One estimate says that just one in seven women breast-feeds exclusively at six months, though the overall rate is about one third of new mothers when those who supplement it with other foods are added in.

While the goal of having 75 percent of new mothers leave the hospital breast-feeding is nearly being met, Lawrence said, “women are not continuing to breast-feed for six months in any great number” especially to the exclusion of all other foods.

The statement did not look into why few women breast-feed up to six months. Lawrence said one reason might be that many return to the workforce soon after giving birth.

La Leche League International, which advocates breast-feeding, says that about 70 percent of U.S. women breast-fed at least once after bearing a child in 2003, based on figures provided by the Centers for Disease Control and Infection.

The number of those breast-feeding exclusively - no water, juice, nonhuman milk or food for the baby - stood at 62 percent seven days after birth but fell to 14 percent at six months.

The policy statement, published in the February issue of the academy’s journal, “Pediatrics,” said updated studies show breast-feeding can lower the risk and severity of ear infections, diarrhea and bacterial meningitis in babies. It also may help protect against crib death, diabetes, obesity and asthma.

For the mother, it can help reduce the risk of ovarian and breast cancer and possibly lead to a decreased chance of hip fractures and osteoporosis after menopause, it said.

The academy said while the percentage of women who start breast-feeding has increased steadily since 1990, overall continuation rates have shown little increase, especially for those who breast-feed exclusively.