In the case of IVF, is it possible to control the number of eggs that are being fertilised? For example, to fertilise only 2-3 eggs that will later be implanted, and not to have any residual embryos frozen?
It is possible to fertilise only a small number of oocytes. The additional oocytes could be cryopreserved without being fertilized. It is not very common, as we don´t know which oocyte will lead into the best blastocyst so a selection is less effective. This is something best to discuss with all the information you bring as a couple (age, reason for infertility ect)