Day 3 or Day 5?
Until about 10 years ago, all embryos were routinely placed in the uterus on day 3 of the cycle when they are at the 5-8 cell stage. Culture methods then emerged which allowed healthy embryos to continue developing to day 5, the blastocyst stage which has several attractive features. Most importantly it allows some of the embryos which are doomed to failure due to internal defects to fall by the wayside as they arrest and do not continue to develop.
Thus the more hardy embryos are self selecting and the rate of implantation of each embryo is higher.Initially it seemed that the ability to choose the more robust embryos by self selection in this manner would raise pregnancy rates. In a common IVF scenario, the choice if a patient had 5 embryos available for transfer, all about equal in quality on inspection under the microscope, the option would be to replace 3 embryos on day 3 or two on day 5. It was hoped that the day 5 embryo transfer would yield higher results for the IVF patient. This has not turned out to be the case. It is however true that the number of multiple pregnancies is reduced by use of the day 5 strategy.
This option remains one to consider when the risk of multiples is paramount. Please refer to the article on this web site under Updates regarding avoiding twins. For individual counseling on these issues, consult your care provider, and additional and personal guidance may be solicited from knowledgeable patient advocates at www.myfertilityplan.com