Feb. 7 (Bloomberg) -- Women who donate their eggs to be used in embryonic stem cell research face minimal risks, mostly from the hormones used to stimulate their bodies to release multiple eggs, according to an Institute of Medicine report.

In studies of women who used these hormones to get eggs that could be used for in vitro fertilization, between 2 percent and 5 percent developed a condition called ovarian hyperstimulation syndrome, according to the report released yesterday.

While most cases were mild and didn't lead to lasting problems, this condition can lead to serious complications including kidney failure or death, in rare case, said the report by a panel of experts convened by the Institute of Medicine, an independent group that provides scientific advice to the government.

``It is a remarkably safe procedure,'' said Linda Giudice, chair of the Department of Obstetrics, Gynecology and Reproductive Sciences at the University of California-San Francisco, and a co-chair of the Institute panel, in a phone interview yesterday. ``The risk of severe disease is actually quite small, but it's not zero.''

Up to now, researchers working with embryonic stem cells have obtained them from embryos left over at fertility clinics when women undergoing in vitro fertilization didn't need them all. Because the supply of leftover eggs is limited, and because they come mostly from white, upper-middle-class women, scientists at universities including Harvard and UC-San Francisco plan to recruit women willing to donate their eggs for research.

Embryonic stem cells, extracted from days-old embryos, are valued because they have the ability to develop into any cell in the human body. Scientists hope they will be able to use the cells to trigger the growth of tissues and organs that can cure hard-to-treat diseases.

Most women who provide eggs for test-tube fertilization or for research take hormones that stimulate their bodies to release more than one egg. These treatments cause mild discomfort, slight enlargement of the ovaries and occasional nausea in most women, Giudice said. A small number of women have more serious symptoms as their rising estrogen levels trigger blood clots or as decreased blood flow to the kidneys leads to kidney failure.

These severe symptoms are experienced by fewer than 0.2 percent of women taking the hormones, the report said. Only 1.4 of every 100,000 women going through fertility treatments experience kidney failure, the report said.

The risk stemming from infection, surgical complications and anesthesia are also ``remarkably low,'' Guidice said. There is no evidence of increased risk of breast or ovarian cancer and too little information to assess the risk of uterine cancer, she said.

Because women who have donated eggs in the past haven't been followed for long periods, these risks represent rough estimates, she said. While the panel didn't make recommendations, Giudice and other members suggested that researchers make a point of tracking the fate of women who donate eggs in the future and pool that information in a database.

The report was commissioned by the California Institute of Regenerative Medicine, the state agency created by voters in 2005 to finance stem-cell research. The institute decided to assess the risk to donors before it begins funding researchers who will make use of donated eggs.

To contact the reporter on this story: Rob Waters in San Francisco at rwaters5@bloomberg.net.

Last Updated: February 7, 2007 00:05 EST