MONDAY, Oct. 14 (HealthDay News) -- Doctors have unveiled a new test for determining which embryos have the best chance of survival.

The amount of mitochondria found in the cells of an embryo appeared to be a marker of its health, doctors reported Monday at the International Federation of Fertility Societies and American Society for Reproductive Medicine annual meeting in Boston. Research presented at meetings is considered preliminary until published in a peer-reviewed medical journal.

Higher levels of mitochondria -- the "powerhouses" of cells -- seemed to indicate an embryo was under stress and less likely to successfully implant in a woman's uterus, said study co-author Dr. Dagan Wells, a scientific leadership fellow at Oxford University in England.

The researchers were able to establish a mitochondrial threshold above which they felt sure an embryo wouldn't be able to implant in a uterus, he said.

By selecting the healthiest embryos, doctors hope to cut down on unsuccessful implantations and miscarriages.

Doctors already can screen embryonic cells to make sure they have the proper number of chromosomes. Previous research has found that if embryos have more or fewer than the usual 46 chromosomes -- 23 from the mother and 23 from the father -- they rarely survive implantation, Wells said.

When doctors add the mitochondria test to the chromosome count, they will be able to increase the rate of successful embryo implantation from between 60 percent and 65 percent to as high as 80 percent, he said.

"We think this will get us to a significantly improved birth rate, and we are planning clinical trials," Wells said.

Dr. Joe Leigh Simpson, president of the International Federation of Fertility Societies, hailed the new findings as creating a "better mouse trap" for screening embryos.

"We can simply add mitochondrial assessment at the same time as chromosomal screening, and better address the disappointment of why we don't get a success," Simpson said. "I would look upon this as providing transformative information. There would be fewer cycles required to produce a baby that one could take home."