Despite standardization of treatment protocols there is a wide variation in pregnancy rates that basically stem from laboratory conditions, experience of the medical staff, and embryo transfer policy.

IVF clinics have been pressurized from the patients and their competitors to increase the number of embryos transferred into the uterus. However, this has been associated with an alarming increase in multiple pregnancy rates.

Regulatory in most European countries and Australia issued imposing restrictions on the number of embryos that can be transferred to a patient. In the American IVF clinic we elect not the transfer more than 2-3 good quality embryos in women < 39. When the embryo quality is suboptimal, when there is a history of multiple failed treatment cycles and when the woman’s age > 39 we replace 3-4 embryos.