How many eggs are retrieved during IVF?

In preparation for the IVF cycle, women are given fertility drugs that are aimed at ovarian stimulation. The course of the drugs can last anywhere between 8 to 14 days. This causes the ovaries to produce multiple eggs rather than just one as during normal ovulation. On an average 10 to 20 eggs are retrieved but not all of them might have attained the appropriate maturity. On average, only two-thirds of the total number of eggs retrieved may be viable for IVF, which is dependent mainly on the ovarian reserve, Drugs used and the Ovarian response to drugs.