I recently attended the American Society of Reproductive Medicine (ASRM) meeting in New Orleans, where the guidelines were again presented for patients undergoing assisted reproductive technologies. These guidelines state that in women under the age of 35 years old, no more than two embryos should be considered for transfer and it’s possible that perhaps only a single embryo may be considered for transfer. In women ages 35 to 37, no more than two blastocyst-stage embryos should be transferred or no more than two cleavage-stage or day three embryos should be transferred. Finally, for patients in the age group of 38 to 40, four cleavage-stage or day three or three blastocyst day five embryos are the recommended limits. For women over the age of 40, no more than five cleavage-stage embryos, which is day three, or three blastocyst day five embryos should be transferred.
In looking at these guidelines, clearly it appears that the major reason for this is to lower the multifetal gestation rate in women undergoing assisted reproductive technologies. At the ASRM meeting, we presented a randomized prospective study which looked at putting back only two embryos in women at the day five stage and utilizing preimplantation genetic diagnosis as a determinate to putting back the best embryos. In that study, the major goal was to limit the incidence of multifetal gestation.
This study, although preliminary, does in fact show that if you put back two day five embryos in these young women, the risk of a multifetal gestation is dramatically lowered. In fact, in the group that underwent PGD, in putting back only up to two normal embryos, there were no multifetal gestations. I think that this will have an impact on the reproductive community and will hopefully by following these guidelines encourage a lower multifetal pregnancy rate.
In Europe of course there are limits to numbers of embryos that are put back, and clearly their multifetal gestation rate is less than that in the United States. However, in the United States of course the driving power many times is for a patient to be successful, and clearly when a patient goes through IVF -- which is an expensive procedure, time consuming, emotionally consuming, and physically consuming -- a patient wants her best likelihood for success. Thus in certain instances, more embryos may be put back than would be followed by the guidelines. So I think that this will have an effect on the reproductive community; however, I do believe that most groups are now following these guidelines.