In an advance that promises to make it vastly easier for older women to remain fertile, researchers at a private clinic in Atlanta said Thursday that they had frozen human eggs, thawed them, fertilized them and created a successful twin pregnancy.
It is the first successful pregnancy in this country using an egg that had been frozen, experts said. Fertility clinics have long been able to freeze sperm and embryos, but they had been stymied by their inability to freeze eggs.One immediate consequence would be to allow women to freeze their eggs
when they are young for use later when they are older and their eggs are of poorer quality. This would make menopause obsolete, in effect, since women could have their own babies, with eggs they stored when they were younger, at any time in life. It would also enable women who are undergoing chemother-apy, which can damage the ovaries, to save their eggs for later use.
Researchers in Hong Kong and Australia reported successful pregnancies from frozen eggs about 10 years ago, but the work was not repeated. One advance that made the new work possible was the ability to fertilize an egg by injecting sperm directly into it. Ordinarily, sperm cannot penetrate an egg that has been frozen and thawed.
Dr. Michael Tucker, an embryologist at Reproductive Biology Associates in Atlanta who led the team that achieved the pregnancy, said that the frozen eggs were from a 29-year-old woman and that they had been frozen for 25 months before he thawed them and fertilized them. The recipient, a 39-year-old woman from Georgia who had undergone premature menopause and so had no eggs of her own, became pregnant and gave birth to healthy twin boys in August.
Tucker said he would describe the results this weekend at a meeting of the American Society for Assisted Reproduction in Cincinnati. He said in an interview that a second woman was 12 weeks pregnant with a fetus his group had created from a frozen egg. He also has nearly 100 other eggs frozen, awaiting recipients.
Infertility experts said they were greatly encouraged. "This is very good work," said Dr. Jacques Cohen of St. Barnabas Medical Center in Livingston, N.J., who is also working on freezing eggs.
"They're a credible group - they definitely did it," said Dr. Alan DeCherney, an infertility expert at the University of California at Los Angeles and editor of the journal Fertility and Sterility. "If this can be repeated, it's a breakthrough."
This month, the journal carries a report by investigators in Bologna, Italy, of a baby girl born from an egg that had been frozen for four months and then fertilized.
Now that the egg freezing barrier seems to be falling, infertility experts said, they will be able to take their art to a new plane, building banks of frozen eggs for infertile women or for those who want to store eggs when they are young for possible use later.
"We all know that the eggs of a woman who is 18 are a lot better than those of a woman who is 48," Cohen said. "If you can freeze eggs of young women, that's what you would want to do."
Dr. Mark Sauer, an infertility expert at Columbia-Presbyterian Medical Center in New York, said that many of his patients are women who decided when they are in their late 30s or early 40s that they were ready to have children. The problem, they discover, is that they are now so old that their eggs are difficult to fertilize.
"If you told men going into their careers when they are in their 20s that by the time they are ready to have kids, their sperm might be no good, you know the men would be banking their sperm," Sauer said. So, he added, if egg freezing is successful, "maybe women should bank their eggs."