( Researchers at Yale School of Medicine ...)Most embryos produced during IVF do not result in live births

Published in the August issue of Fertility and Sterility, the study reviewed seven years of U.S. statistics from all the fertility clinics that report data on reproductive techniques. Director of the Yale Fertility Center, Pasquale Patrizio, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences led the project.

"Something in nature has decided that these implanted embryos are not viable," said Patrizio, who conducted the study with co-author George Kovalevsky, M.D.

"We as practitioners in the reproductive clinic are in a paradoxical situation," Patrizio added. "There is pressure to reduce multiple births, but we need to do so knowing that the majority of the embryos that are transferred do not implant. It is difficult to strike a balance between these two needs."

Patrizio said he and his fellow physicians strive to better identify the embryos with the most potential. But addressing the growing pressure to transfer fewer embryos to reduce multiple births is a difficult task unless they can come up with a method in the lab to identify the best embryos.

"Some potential methods for screening embryos include using pre-implantation genetic diagnosis and biochemical markers of embryo viability," said Patrizio. "In addition this study should also move the field toward perfecting methods of egg production."