After three years of trying to conceive a child, Michele and Jeff Turner learned they were infertile. "Our doctor told us, 'You have a better chance of winning the Powerball lottery than of conceiving a child naturally,'" said Michele, now 33.

In vitro fertilization (IVF), or seeking to produce an embryo outside the womb, was also a long shot. After two failed IVF attempts, the Turners looked into adopting a child and raising a family in their Royer's Ford, Pennsylvania home. The cost (more than $20,000 in their area) was prohibitive.

Then, during a meeting of a national infertility support group, they heard about frozen embryos left from infertility treatments.

After contacting about 40 fertility clinics, the Turners joined an embryo donation program at the Cooper Institute for Reproductive Medicine in Mont Clare, New Jersey. Later, they received embryos from a donor family. In December 1999, Michele gave birth to twin daughters, Morgan and Macy.

Then, when their daughters were nine months old, Jeff and Michele discovered she was pregnant with a son, Myles, who was conceived naturally. They had to relinquish their rights to some remaining donated embryos, which were considered property of the clinic.

"It was an excruciating thing to do," Michele said.

A new study, by the Society for Assisted Reproductive Technology and the RAND Corporation, found that fertility clinics in the United State have nearly 400,000 frozen human embryos in storage—twice the highest previous estimate.

The survey of 430 clinics showed that 88.2 percent of the embryos are being stored for possible future use. About 11,000 are set aside for scientific research. About 9,000 are designated for infertile couples. Another 9,000 will be thawed and destroyed.

The ...