Embryo production varies greatly from donor to donor and flush to flush. Average production is approximately 6 freezable (Excellent & Good) and 8 transferable (Excellent, good, fair & poor) embryos per super-ovulation.
Pregnancy rates vary from flush to flush with fresh averages 60-70% and frozen 50-60%. Many factors affect pregnancy rate such as embryo quality, recipients, technical ability, and donor. Some donors consistently produce embryos with higher pregnancy rates that others with embryos of similar grade. This last factor seems to be uncontrollable and unpredictable.