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Long-Term Freezing Doesn't Harm Embryos : In one case, twins resulted from an embryo stored 11.8 years by a donor aged 38 years at storage time.


 

INDIAN WELLS, CALIF. — Successful pregnancies and deliveries have resulted from donated embryos that had been frozen for more than 10 years, raising questions about arbitrary deadlines for unused embryos to be destroyed.

Researchers at the Cooper Center for In-Vitro Fertilization in Marlton, N.J., studied the viability of frozen embryos anonymously donated to infertile couples to see whether long-term freezing had an impact on their quality or survival.

Results were presented in poster at the annual meeting of the Pacific Coast Reproductive Society. (See chart.)

“There did not appear to be any decrease in pregnancy or implantation rates with longer storage duration. In contrast, there seemed to be a trend for the older embryos to do slightly better, with a higher pregnancy rate and lower spontaneous abortion rate, although this was not significant,” noted Dr. Jerome H. Check, medical director of the center, and his associates.

In two cases, live births resulted from embryos that had been frozen for more than 10 years.

A twin pregnancy resulted from an embryo stored 11.8 years by a donor who was aged 38 years at the time of storage. A total of six embryos were available for transfer and all survived thawing. Among the three transferred embryos, all reached the eight-cell stage and were of good quality. The recipient was delivered of a healthy boy and girl at full term.

A second live birth resulted from an embryo stored for 10.8 years by a 27-year-old donor. Three of four embryos available for thawing survived and two were transferred. Both had good morphology and had reached the eight- and nine-cell stage, respectively, at the time of transfer. A pregnancy resulted in the birth of a healthy, full-term boy.

A literature search revealed that the longest time a multicell embryo has been frozen and then resulted in a delivery was 12 years, but an increasing number of reports suggests that healthy babies can result from embryos frozen indefinitely.

“These data are important, since legislation in some countries allows or requires embryos to be destroyed after 2–5 years of storage,” the poster noted.

“Unequivocally, cryopreserved embryos can produce viable pregnancies and deliveries far beyond this arbitrary cutoff time. When considered in combination with a voluntary embryo donation program, it seems wise to allow [in vitro fertilization] couples the option of cryopreserving supernumerary embryos and donating them when no longer needed,” no matter how long the time period, the authors said.

The Cooper center is part of Cooper University Hospital, where Dr. Check serves as professor of obstetrics and gynecology and director of reproductive endocrinology. It is the teaching hospital for the University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School-Camden.

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