In the first known case in Minnesota, a woman is pregnant from a human donor egg that was frozen and thawed before it was fertilized and implanted in her.

The woman's fertility doctors used in vitro fertilization (IVF) to achieve the pregnancy in a 48-year-old woman, who does not want to be identified. She is only nine weeks pregnant and still runs a risk of miscarriage.

Her pregnancy means that egg freezing, a controversial technology many say is not yet ready for prime time, is now available in Minnesota.

The woman's doctor, Dr. Jacques Stassart of Reproductive Medicine and Infertility Associates in Woodbury, said the technology is still experimental, but the clinic will offer it on a case-by-case basis. Early next year he will hold educational seminars for patients and market it to cancer doctors for young women patients at risk of losing their fertility from medical treatments.

But the potential market is much larger -- the millions of women who are increasingly delaying child bearing or who want to bank their eggs as insurance against infertility. Experts say egg freezing is the only way to defeat nature by bringing the biological clock to a halt and that it could revolutionize women's reproductive lives as much as the birth control pill did 40 years ago.

Stassart's clinic, one of five IVF clinics in Minnesota, is among an estimated 138 across the country offering egg freezing and storage. But to date only 300 to 600 babies around the world have been born from frozen eggs. Though the technology is advancing rapidly, even the American Society for Reproductive Medicine (ASRM) recommends it be limited to cancer patients and research studies.

But fertility doctors, who operate largely without federal oversight or research dollars, have a long history of trying new technologies on patients. In effect, the federal government "has shunted the responsibility of research onto the patient community," said Jeff Kahn, director of the Center for Bioethics at the University of Minnesota.

With egg freezing, fertility clinics are once again experimenting on patients, said Dr. Marc Fritz, chairman of the practice committee for ASRM.

"What it boils down to is a clinical investigation of an experimental procedure in patients at their expense," Fritz said. "That is what the society feels is not appropriate."

Why is it so hard?

Human eggs are large and delicate, and for decades have resisted attempts to freeze them the way sperm and embryos can be frozen. The first pregnancies from frozen eggs were reported in 1986, but until recently the process had advanced very slowly.

Eggs are full of water, which crystalizes, destroying the cell structure much like water frozen in a bottle expands and cracks the glass. Embryologists now replace the water in the cell with sugar or glycerol-based products. And they use either a slow freezing technique or a fast one called vitrification that takes the egg to a temperature of negative 196 degrees centigrade in minutes - too fast for crystals to form.

This latest technological development comes at a time of increasing competition for IVF clinics. Baby boomers are moving past reproductive age, leaving doctors to compete over a smaller number of infertile people in Generation X. Among Minnesota's IVF clinics, Stassart's has always been the boldest in marketing to patients. Doctors at the other clinics were either unavailable Friday or did not return phone calls.

Stassart said the clinic will follow the guidelines issued by the ASRM on properly informing patients about the procedure. "We are not going to open the front gates with a big sign that says 'We freeze eggs,'" Stassart said. "We have to be super careful about not misrepresenting this."

An accidental first

The patient used frozen eggs because of a mistake.

Chris Gooder, the clinic's marketing director, said the woman used a donor for eggs because of her age. But when the donor's eggs were ready for retrieval, the clinic realized the woman's husband had mistakenly told clinic staff to destroy his sperm samples - and at the critical moment he was out of town.

"It was an oops," Gooder said.

The clinic has been developing an egg freezing process for two years. So doctors suggested freezing the eggs until the woman's husband returned. Later, they were thawed and fertilized with her husband's sperm. The resulting embryos were frozen until she was ready to have them transferred to her uterus. Doctors transferred two and one survived.

Dr. David Ball, the embryologist at Reproductive Medicine and Infertility Associates who developed the procedure, said that 70 to 80 percent of the eggs he's frozen survive the thawing process - compared to about 90 percent of frozen embryos. Based on results from other clinics around the world, about 20 to 25 percent of frozen and thawed eggs can result in a live birth, he said. That compares to about a 50 percent success rate with fresh eggs.

Still experimental

Both the ASRM and the Society for Assisted Reproductive Technology say egg freezing should not be marketed to healthy women because data on outcomes are limited.

A 2006 article in the journal Fertility and Sterility reported IVF success rates with slow-frozen eggs are significantly lower than with unfrozen eggs. As for vitrification, more study is needed to determine both safety and effectiveness, it said.

For women who pursue egg freezing anyway, new guidelines issued by the two groups in October list recommendations for extensive pre-treatment counseling including information on annual storage fees, thaw-survival rates, the risks of basing important life decisions on a limited number of frozen eggs and the possibility that a facility may close.

However, the October report noted that women with cancer or other illnesses may have no viable options and "therefore may be appropriate candidates for such treatment despite its experimental status."

These include more than 50,000 American women younger than 40 who develop cancer each year. For them, treatment advances -- including aggressive chemotherapy, radiotherapy and bone marrow transplantation -- have sharply raised cure rates, but they often render the patients infertile.

Despite the hope that egg freezing offers such women, most don't have the two to three weeks or longer it takes to complete a cycle of egg stimulation and retrieval before they have to start cancer treatment. 612-673-7394 612-673-7434