IVF & PGD: What is the Success Rate?
Some doctors are telling their patients to transfer abnormal embryos during IVF. Is this a good idea for you?
How to identify abnormal embryos
The majority of embryos that human beings make are abnormal. This means they did not have the correct number of chromosomes. When embryos are created outside the body during IVF, it is possible to test the embryos to determine if they have the correct number of chromosomes.
This type of testing is called PGD or the newer term is PGT.
What if all your embryos are abnormal? Should you consider doing an embryo transfer with an abnormal embryo? Some doctors are recommending that their patients do this.
Those recommendations are based on the assumption that in some cases the PGD test results might be wrong and you could therefore be throwing out an embryo that has some chance to produce a healthy baby.
Recently, doctors attempted to answer a seemingly simple question:
Can you rely on abnormal PGT results?
If you test an embryo and it is abnormal... Can you rely on the results? In other words, will an abnormal result accurately predict the failure of that embryo to produce a viable healthy baby?
Really, the only way you can determine this for sure is to go ahead and transfer those abnormal embryos and see what happens. These doctors designed a study to do just that. Here's how it worked.
They recruited several hundred couples who were undergoing their first IVF cycle. If those couples made at least one embryo that developed to the blastocyst stage, the embryos were biopsied and tested but the results were not revealed to the doctors or the patients.
A single embryo was transferred based only on its appearance under the microscope, not based on the test results. Those results were only revealed later after the outcome of the embryo transfer was known.
Results of the PGT non-selection study
Here are those results. As expected, embryos from older women were more likely to have abnormal test results. If the embryo transferred happened to be normal, 65% of those embryo transfers resulted in an ongoing pregnancy or delivery.
If the embryo transfer happened to be abnormal, there were no viable pregnancies produced. There were over a hundred embryo transfers performed with abnormal embryos and not one resulted in a baby.
Abnormal embryos implant less and miscarry more
If you dig a little bit deeper into the data you will find that the failure to produce a viable pregnancy was because, compared to normal embryos, the abnormal embryos were half as likely to even implant and more likely to miscarry.
We can say with certainty that even with all of the potential sources of testing errors, the reproductive potential of embryos that have an abnormal test result is extremely low.
Embryo biopsy did not impact IVF success
One other thing when the doctors compared the outcomes of all of the transfers that were done with embryos that were biopsied, both normal and abnormal, and compared them to a similar group of patients that had embryo transfers of unbiopsied embryos, they found no difference. This indicates that the biopsy itself did not cause any lowering of the success rate.