Eight babies have been born after being frozen and stored as embryos, a new technique that could make test tube conception more successful, American Medical News reports.

The freezing process allows doctors to remove several eggs from a women in a single procedure, store them, and later implant only one at a time. Current test-tube conception techniques require the implantation of more than one fertilized egg to increase chances of success.

"On one hand, to expose too few eggs to fertilization risks failure," says Dr. Howard Jones of the Jones Institute for Reproductive Medicine in Norfolk, Va. "And transferring all fertilized eggs risks multiple births."

After freezing and thawing, about 60 percent of embryos are too damaged to implant.

With the freezing technique, if one egg is implanted and a pregnancy results, left-over embryos can be implanted in infertile women, he says. Cost of the procedure at one clinic is $5,100, plus $450 for freezing. The freezing charge is waived if the couple donates extra embryos for adoption.

Two of the births have been in Holland, the other six in Australia. Twenty attempts at the University of Southern California have failed.

But Dr. Geoffrey Sher of the Reno Women's Clinic says he currently has 15 to 20 embryos frozen in liquid nitrogen -- each about four to six cells in size -- ready for implantation before summer.