Women in their sixth or even seventh decade of life can get pregnant with relative ease using eggs from younger women, and can expect to have reasonably normal pregnancies and healthy outcomes, according to a new study, the largest of its kind.

The new findings confirm previous evidence that it is older women's eggs, not their wombs, that go into decline at menopause, leading to age-related fertility problems. The frequency of certain complications such as pregnancy-related high blood pressure does increase with age, the new study notes. But those problems can be minimized with careful oversight, the researchers conclude.

"On the basis of these data, there does not appear to be any definitive medical reason for excluding these women from attempting pregnancy on the basis of age alone," wrote Richard J. Paulson and colleagues at the University of Southern California in today's issue of the Journal of the American Medical Association.

The practice of helping women become pregnant in their fifties and sixties has been controversial since the first cases were documented more than a decade ago. The ethics committee of the American Society of Reproductive Medicine concluded six years ago that the practice is not unethical but should be discouraged.

Others echoed that view yesterday, warning against wide promotion of the practice. "Just because you can do something doesn't mean you should," said Robert Stillman, medical director of the Shady Grove Fertility Reproductive Science Center in Rockville. Like many U.S. fertility clinics, the center refuses to treat women older than 50, the approximate average age of menopause. "We're obligated as physicians to provide medical therapy to those with a medical disorder, and we believe that the medical disorder of infertility is confined to the normal reproductive lifespan," Stillman said.

Paulson's group acknowledges that there are medical, psychological and social impacts of late motherhood that deserve careful consideration. But for women who want to go down that path, they conclude, the odds of success are remarkably good when they use donor eggs from women in their twenties and thirties.

Paulson and his colleagues tracked the fates of all 77 postmenopausal women, ages 50 to 63, who underwent in vitro fertilization with donor eggs at USC from 1991 to 2001. Each had to pass a thorough medical exam, including a cardiac stress test and a uterine lining biopsy to ensure that the womb could still respond to the hormones that would be given to support the pregnancy.

The women had, on average, three to four embryos transferred to their wombs. All told, 42 of the 77 women had live births -- including three who each had two consecutive -- for a total of 45 births, producing 61 babies (31 single children, 12 sets of twins and two of triplets), all of them healthy. More than half of those women had never had children before. Some had recently lost a child or married, Paulson said.

Most of the babies -- and all of the twins and triplets -- were delivered by Caesarean section, a higher rate than normal even for IVF mothers who, for a variety of medical and other reasons, have twice the C-section rate of other pregnancies. Paulson suspects that older uteruses are less able to produce the contractions needed for vaginal delivery.

The incidence of gestational diabetes in the pregnant women was also elevated, with about 20 percent of the women affected (compared with the usual 5 percent or so for women in their teens and twenties and about 14 percent for women over 30). Most cases required only dietary changes.

The biggest complication was pre-eclampsia, a form of high blood pressure that can harm the developing fetus, which affected about a third of the women. That's a tenfold higher rate than is typically seen in young women and about three times the rate for women older than 40. But with the exception of one woman in whom the syndrome forced early delivery of her twins at 30 weeks, the problem was treated with standard means, including bed rest.