The rate-limiting factor for IVF success is the quality of the embryo. Embryo quality in turn is almost entirely dependent upon egg quality. All the eggs a woman will ever have are those that she was born with; no new eggs are produced after birth. Consequently, as a woman gets older, so too do her eggs. As eggs age, their capacity to make good embryos and to support pregnancy also declines. By the start of the thirties, this egg-decline begins to have a marked impact on embryo- and pregnancy-potential and becomes particularly pronounced after the mid-thirties. It is for these reasons that IVF success is directly related to female age and why IVF success rates are typically reported with reference to female age.
Because of this impact of female age, the highest IVF success rates occur for women under 35 years of age. Success rates become markedly reduced after the age of 37 years and especially after 40 years of age. Because of this ageing effect, the success rate for someone in their late thirties is roughly half that of someone in their early thirties.
The success of an IVF cycle is also strongly influenced by the quality of the embryology laboratory and importantly, the expertise of the treating clinician.
Professor Homer is an internationally leading expert in egg quality and the effects of ageing. His lab is actively researching novel treatments for reversing poor egg quality. Click here to read his recent paper on the effect of ageing on egg quality published in the world’s top reproduction journal.