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.(Gynecology)(research)

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.