IVF Embryo Screening: Pregnancy Boost?
Researchers Say Technique Lowers Pregnancy Chances for Women Having in Vitro Fertilization
Criticism of the Study continued...
"This research team is inexperienced," says Santiago Munne, PhD, a member of the board of directors for the Preimplantation Genetic Diagnosis International Society, a Chicago-based organization that coordinated research, education, and training in the technique.
Munne and other critics say that inexperience affected the results. For instance, 20% of the embryos tested came up with "undetermined" results, with the researchers unable to term them normal or abnormal. "Experienced centers typically have a 5% indeterminate rate," Munne tells WebMD.
The undiagnosed embryos were transferred to the women, resulting in an implantation rate of 6% compared with the higher 14.7% implantation rate in the group of patients whose embryos did not have biopsies, he says.
"In our study, all biopsies were performed on the third day after insemination, which is very normal in the case of preimplantation genetic screening," Mastenbroek responds.
"Our results are in line with all other data available in the scientific literature," he adds. "A beneficial effect in terms of ongoing pregnancy has never been shown for PGS. Lower ongoing pregnancy rates have been shown before, but this outcome was significant in our trial since this is the largest randomized trial available today."
Now, he says, his team is investigating why the technique was ineffective.
In an editorial accompanying the study, John A. Collins, MD, a physician at McMaster University in Hamilton, Ontario and Dalhousie University, Halifax, Nova Scotia, Canada, puts the results in perspective: "The results suggest that for every nine women who are 35 to 41 years of age who plan three cycles of IVF or IVF and intracytoplasmic sperm injection, there will be one more live birth if pre-implantation genetic diagnosis for [abnormalities] is not performed."
In an email interview, Collins tells WebMD that the new study results are "convincing most people in the field that PGS has no value in screening infertile women over 35 undergoing IVF."
In his editorial, Collins advises that the preimplantation screening not be done solely due to a woman's age.