Mothers who breastfed their children for a combined period of one year were 10 percent less likely to have heart attacks, strokes or heart disease later in life than those who never nursed, according to a study by University of Pittsburgh researchers published in the May issue of Obstetrics & Gynecology.

Even women who breastfed for just one month were less likely to have high blood pressure, diabetes or high cholesterol, all contributors to heart disease, the observational study said.

"Any amount of breastfeeding is better than none, and the more the better in terms of [preventing] risk factors as well as heart disease itself," lead author Eleanor Bimla Schwarz, M.D., said yesterday in an interview.

"We always hear it's good for babies and their health and hear less about the benefits for women," added Dr. Schwarz, assistant professor of medicine, epidemiology, and obstetrics, gynecology and reproductive sciences at Pitt. "This joins other studies in showing breastfeeding has an important role in helping women recover from pregnancy.

"Women who have been pregnant and don't breastfeed don't allow their bodies to recover in the way nature or God intended."

The findings were based on examined data from 139,681 postmenopausal women who reported at least one live birth in enrolling in the Women's Health Initiative controlled trials or observational study of chronic disease.

The WHI, begun in 1994, involved 161,808 women age 50 to 79 at enrollment, but the Pitt study excluded the women who had not given birth, those for whom information on births or duration of nursing was missing, and those who reported only stillbirths.

The Pitt researchers also used math models to make adjustments for a wide range of variables, including race, ethnicity, education, income, diet, physical activity, whether they smoked and whether they used a variety of supplements ranging from hormone therapy to aspirin to multivitamins.

"We did control for a lot of things, more than are standardly considered," Dr. Schwarz said, when asked if some unidentified factor rather than breastfeeding could have been responsible for the lower incidence of heart disease. "I'm pretty convinced this is a real finding and that if you threw even more things into the model, it would still be there."

The researchers found that the benefits of nursing were long-term, since an average of 35 years had passed since the women had breastfed. Yet they also determined that those benefits declined with old age.

"It is long-term, since you saw effects for years," Dr. Schwarz said. "However, when we looked at women in their 80s versus women in their 70s versus women in their 60s, it did seem to make less difference as the women got older. It could be other things in their lives had caught up with them. There are just all sorts of other things that can have an effect."

Dr. Indu Poornima, director of the Center for Women's Heart Disease at Allegheny General Hospital, said the study "if replicated, prospectively would have significant health implications on the incidence of diabetes and hypertension."

She also noted that it is "basically a confirmation of the same result in a different population." She was referring to the Nurses' Health Study, begun in 1976, which reported that women who breastfed for a longer period had a lower incidence of diabetes later in life.

There was a weakness in the Pitt study, Dr. Poornima said, since the data was based on the women's memory of how long they had breastfed many years earlier.

Also, she said, both it and the Nurses' Health Study failed to account for "pregnancy-induced hypertension ... that makes them more prone to developing hypertension later in life."