P–136 Factors predicting clinical outcomes of 511 recipients of vitrified oocyte donation from an UK-regulated egg bank

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Abstract Study question Do established donor and recipient clinical markers predict recipient clinical pregnancy and live birth rates (LBRs) in a vitrified oocyte donation programme? Summary answer Recipient BMI and previous miscarriages predicted cumulative LBR. Likelihood of clinical pregnancy and LBR was higher in recipients of donors aged 23–29 than donors 18–22. What is known already The influence of age on ovarian reserve underlies the upper limit of 35 years for UK donors. However, recent evidence suggests that oocyte aneuploidy rates follow an inverse U-shaped curve in relation to a woman’s age. Conflicting evidence exists regarding the impact of other donor-related factors including BMI, AMH, oocyte yield and prior reproductive history on recipient outcomes. Moreover, the effect of recipient age, BMI, and reproductive history on oocyte donation outcome remains unclear. Study design, size, duration Retrospective cohort study of 325 altruistic oocyte donors matched to a total of 511 recipients. Only first donations taking place between January 2017 and December 2019 were included. Participants/materials, setting, methods All oocyte donors were altruistic volunteers aged 18–35 with no prior infertility diagnosis. Donor and recipient screening for suitability and safety was carried out according to the Human Fertilisation Embryology Authority guidelines. Backward stepwise logistic regression was used to identify donor, recipient and embryology parameters predictive of recipient primary outcomes defined as clinical pregnancy and live birth, either cumulative or after the first embryo transfer (ET). Main results and the role of chance A total of 705 fresh and frozen/thawed ETs were performed, of which 76% were elective single embryo transfers (eSETs) of blastocysts (96.5%), resulting in a cumulative clinical pregnancy and LBR of 83.5% and 70.5% respectively after 3 ETs. Recipient BMI and previous miscarriages were predictors of cumulative LBR (p < 0.05). The ratio of transferrable embryos per oocytes received/fertilised and the number of ETs needed to achieve the intended primary outcome were predictors of cumulative clinical pregnancy and LBR (p < 0.05). Donor age 18–22 was associated with lower incidence of recipient clinical pregnancy and live birth after the first ET, as compared to donor age 23–29 (p < 0.05). Limitations, reasons for caution The present study included only healthy oocyte donors, thus conclusions may not apply to subfertile or less healthy women. Male factors were not accounted for. Wider implications of the findings: We demonstrate the efficacy of vitrified oocyte donation treatment and identify recipient BMI, previous miscarriages and embryology parameters as predictors of cumulative LBR. Additionally, the choice of donors aged 18–22 instead of older donors is found not to be advantageous for increasing the chance of clinical pregnancy and live birth. Trial registration number Not applicable