First successfully used in 1978, in vitro fertilization (IVF) is now used routinely as a form of assisted reproductive technology (ART). While the cumulative likelihood of live birth by the fifth embryo transfer cycle is currently about 80%, there remains an urgent need to improve treatment protocols, considering the high financial and psychological burden of the many failed IVF cycles. The main determinants of live birth are age and ovarian reserve, but individual differences in hormone levels strongly affect IVF outcome.