Further improvement in IVF outcome may need more than consistency in ovarian stimulation

It is agreed that reliability of hormonal products, starting with recombinant technology, has improved uniformity of ovarian response to a specified dosage, and that this has resulted in better pregnancy rates. Nevertheless, IVF cycle cancellation rate has not experienced a substantial decline in the last 5-10 years. We feel that further improvement will be more likely to be achieved once we gain better understanding of factors intrinsic to oocyte biology, such as oocyte ageing and oocyte depletion.