But the new study also shows the limitations of transferring such embryos. A large majority of the 144 embryos transferred by the group had only one or two chromosomal aberrations, but the transfers led to 11 abortions in addition to the eight live births.
“There are a lot of abortions in that relationship,” said Laura Hercher, director of student research at Sarah Lawrence College’s genetic counseling program.
The PGT-A test is used to screen for aneuploidy, which is when an incorrect number of chromosomes – either too few or too many – are detected in sample cells. An abnormal number of chromosomes can in severe cases lead to genetic disabilities, such as Down syndrome. More often, the wrong number of chromosomes can lead to failed pregnancies, either by preventing embryos from implanting or by causing abortions.
But the problem with PGT-A, the authors of the study claim, is that it provides an incomplete picture that is often interpreted as a very definitive result. The test is based on sampling a handful of cells from the outer shell of the developing embryo and testing to see if each one has 23 pairs of chromosomes.
“The point of PGT was to select embryos that would give someone a better chance of getting pregnant,” said Dr. David Barad, an OB-GYN at the Center for Human Reproduction and co-author of the study. “But performing genetic tests does not make embryos better, it just gives us an idea of who they are.”
While there may be some risk in continuing to use these embryos with abnormalities, the authors of the new study, all of which were affiliated with the clinic performing the transfusions, claim that viable embryos are currently being neglected, leaving many women to believe that they have no other options to achieve a pregnancy.
“The abortion rate is pretty much what one expects at such a high age,” said Dr. Norbert Gleicher, director of the clinic and co-author of the study, via email. He added: “Ask women what they prefer. Risk of miscarriage or no chance at all of having a child. The answer will be clear.”