Unfertilized Eggs May Remain Viable After Freezing, Thawing, Study Says
September 14, 2004
New research indicates that unfertilized eggs retrieved from a woman's ovaries may still be viable after being frozen for a period of time and then thawed, a finding that "offers new hope" to women who wish to delay childbearing, according to a study published in the September issue of the journal Fertility and Sterility, the Washington Post reports. Although sperm and embryos are regularly frozen for later use, previous attempts have indicated that unfertilized eggs often are damaged during the freezing and thawing process. As a result, women who had their ovaries removed or women who want to delay childbearing until after menopause had to decide who the sperm donor would be -- a "decision that many women in that situation want to delay" -- so that their eggs would survive the cryopreservation process, the Post reports.
Andrea Borini of the University of Bologna in Italy and colleagues froze a total of 737 eggs retrieved from 68 women -- 51 of whom were undergoing immediate in vitro fertilization and wanted to preserve additional eggs for future procedures. Seventeen of the women wanted to preserve their eggs and had no desired sperm donor at the time. Approximately 272 of the eggs survived thawing after various periods of time, about 122 of which were successfully fertilized. Of the fertilized eggs, 104 of the healthiest were implanted in the women's wombs. Although most did not result in pregnancies and three miscarriages occurred among those that did, 13 births were reported among the study participants (Weiss, Washington Post, 9/13). "[I]t appears that (eggs) that are able to survive freezing and can be fertilized, allow preimplantation development and implantation with acceptable rates," according to the study (Reuters Health, 9/13). However, researchers have said that additional examination is needed to improve the procedure and definitely show that it does not result in genetic abnormalities, according to the Post (Washington Post, 9/13).
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