Egg sharing for assisted conception: a window on oocyte quality.

The steep decline in both natural fertility and success after assisted reproduction treatment with increasing maternal age is universally recognized. Large variations in the developmental competence of oocytes collected are seen during assisted cycles,and a link between the biological competence of oocytes retrieved and age has been confirmed. Patients who require donated oocytes can benefit from egg sharing programmes, in which a proportion of oocytes collected from selected patients aged 35 years undergoing conventional assisted reproduction treatment are shared with a matched recipient. The reproductive outcomes of the egg provider and recipient can thus be compared to quantify the significance of oocyte quality. Data gathered from two comparable treatment centres resulted in 285 pairs of egg sharing providers and their recipients that could be analysed statistically. The chief finding was donor pregnancy as a predictor of recipient pregnancy given embryo transfer (odds ratio 2.15, 95% confidence interval 1.33–3.46, P ≈ 0.002), despite an appreciably higher mean age of the recipients. The probability of a recipient pregnancy increased by almost 0.2. Such results strongly indicate the key importance of oocyte quality for a successful clinical outcome in egg sharing practices and assisted reproduction treatment more generally.