Many Frozen Embryos Go Unused, Study Says

Filed under: In The News, Infertility

A researcher handles frozen embryonic stem cells in a laboratory at the Univestiry of Sao Paulo's human genome research center, in Sao Paulo, Brazil. Credit: Mauricio Lima, AFP / Getty Images

Many women who successfully have a baby using donated eggs do not try to get pregnant a second time using extra embryos they have stored, according to a study completed at one fertility clinic. The researchers say that the findings suggest that more fertility treatment centers should consider offering "shared donor" programs, in which eggs from a single donor are given to two women seeking in-vitro fertilization (IVF), rather than one.

Since fewer eggs go to each patient, shared donor programs can be an important option for women seeking IVF, as it means lower overall costs. The average cost in the U.S. for one IVF treatment cycle is $12,400, according to the American Society for Reproductive Medicine, and is higher when a woman must use donor eggs instead of her own. Lower costs could allow more women to take advantage of IVF. In addition, the study suggests that there would then be fewer unused embryos.

Published last month in the journal Fertility and Sterility, the study looked at 829 women who underwent IVF using donor embryos at the New York University Fertility Clinic between January 2000 and December 2004. Researchers found that more than half -- 54 percent -- of the women had a baby, or multiples, after that 40 percent of those women elected to freeze and store any extra embryos that were not implanted. However, by August 2009, only 21percent of the women who had their embryos stored actually returned to the clinic to try for a second pregnancy using the stored embryos. For women whose initial attempt at IVF failed and had their extra embryos frozen, 87 percent returned for a second attempt.

According to Reuters, the research team, led by Jaime M. Knopman, M.D., concluded the findings suggest that most women conceive using donor eggs "are satisfied after experiencing only one successful outcome," and added that many women who give birth to multiples may be especially likely to feel this way; out of 81 participants who had twins after their first attempt, 74 did not return to use their extra embryos.

The NYU fertility clinic offers patients the option of using either an "exclusive" or shared anonymous egg donor. With the shared donor, two women can receive eggs from one donor, as long as there are at least 12 eggs available. Knopman's team suggested that since the number of women who want donor eggs is growing, and the number of donors is limited, fertility centers should considered a shared donor program, which they suggest "will maximize efficiency, reduce costs, and achieve fertility for a larger number of infertile patients," and "would markedly reduce the number of unused frozen embryos."

In related news, a recent study on IVF completed in Finland suggests that women who use frozen embryos are somewhat less likely to give birth prematurely, compared to those who use an egg that is removed, fertilized and implanted "fresh" within the same cycle. In addition, the study found that frozen embryos were also less likely to be linked to low birth weight and being small for the length of the pregnancy. The researchers did find that there was a higher incidence of premature births from frozen embryos vs. natural conceptions, but there were no significant differences in fetal or infant mortality among any of the groups.

Published in the journal Human Reproduction, the Finnish study is notable because it could clear up some misconceptions about using frozen embryos. "There's a sense people have that frozen aren't as good -- that freezing and thawing could harm the embryos. This quiets those concerns," Dr. Helen Kim, Director of the In Vitro Fertilization Program at The University of Chicago, told Reuters in a phone interview.

The researchers did not, however give a definitive reason as to why frozen embryos result in more favorable outcomes. In an email to Reuters Health, Dr. Gordon Baker of the University of Melbourne and The Royal Women's Hospital in Australia commented that the freezing and thawing process could filter out the "weak" embryos, leaving only the good quality ones. He also added that frozen embryo transfer also allows doctors to time a woman's hormone cycles to more closely mimic natural conception.

It remains to be seen if findings like those from the Finnish study will serve to influence a woman's decision about using extra embryos that are frozen for storage after a first IVF attempt, but clearly more research needs to be done to pinpoint causes and effects.

Related: Should I Have Infertility Testing?

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