Nowadays it's unusual to freeze embryos so soon after fertilization (about 12 to 18 hours). Instead, clinicians monitor embryonic development for three to five days in an attempt to identify those that are more likely to result in healthy pregnancies after transfer. Despite their best efforts, though, they have only about a 35 percent success rate. As a result, most women elect to transfer two or more embryos to increase the chance of a live birth. However, if multiple embryos implant and develop successfully, a woman and her physician may choose to selectively abort one or more to better the odds for the remaining embryos.
Reijo Pera and her colleagues received a large grant from an anonymous donor to investigate ways to better predict embryonic developmental success within one or two days of fertilization. Not only would such an advance decrease the likelihood of miscarriage or the possible need for a selective reduction, it would also reduce the amount of time the embryo would be have to be cultured in the laboratory before transfer. (Although it's not been conclusively shown, some researchers are concerned that genetic changes may accumulate in a cultured embryo and cause subtle, long-lasting effects in the fetus.)
The researchers thawed the embryos, split them into four groups and tracked their development during the first few days using time-lapse video microscopy and computer software specially designed by Loewke, a former Stanford mechanical engineering graduate student, for this study. They followed the cells through the development of a hollow ball called a blastocyst, which t
|Contact: Krista Conger|
Stanford University Medical Center