One Embryo Better Than Two?

A study by Finnish researchers published in the current issue of the journal Human Reproduction finds that transferring a single fresh embryo at a time, followed by subsequent transfers of individual thawed embryos, may be as effective in achieving pregnancy as implanting multiple embryos at once. Using one embryo at a time also cuts medical costs, the study found, saving about $27,000 per live-birth pregnancy.

Some of that success can be attributed to improvements in freezing techniques, says Dr. Hannu Martikainen, the study's lead author and the chief physician at the University of Oulu Division of Infertility and Reproductive Endocrinology. "Now we have more and more experience, and we are doing more and more frozen cycles," he says. He points out the importance of not only transferring but also preserving each embryo on its own, which makes it possible to use frozen embryos one at a time rather than in bigger batches. "[If you transfer] three embryos in each cycle, you very soon don't have any good-quality embryos left," he says.