Minimum number of mature oocytes needed to obtain at least one euploid blastocyst according to female age in in vitro fertilization treatment cycles

Abstract

Objective: To find a useful tool for estimating the minimum number of metaphase II (MII) oocytes needed to obtain at least one euploid blastocyst according to female age.

Design: Retrospective analysis of in vitro fertilization (IVF) treatment cycles with preimplantational genetic testing for aneuploidies (PGT-A) performed over 5 years in IVIRMA Valencia (Spain), January 2017-March 2022. Approval from the Institutional Review Board of IVI Valencia (2204-VLC-040-CR).

Setting: Private infertility clinic in Spain.

Patients: Eligible patients were undergoing their first IVF-PGT-A treatment cycle, in which at least one MII oocyte was obtained, regardless of oocyte and semen origin. Oocyte donation cycles were included in the donor group (≤34 years old). Treatment cycles from women with their own oocytes were selected only when the oocytes were aged ≥35 years (patient group). Only trophoectoderm biopsies performed on days 5 or 6 of development and analyzed using next-generation sequencing were included. Preimplantational genetic testing for aneuploidy cycles because of a known abnormal karyotype were excluded.

Intervention: Not applicable.

Main outcome measures: Number of MII oocytes needed to obtain one euploid blastocyst according to female age.

Results: A total of 2,660 IVF-PGT-A treatment cycles were performed in the study period in the eligible population (patients group = 2,462; donors group =198). The mean number of MII oocytes needed to obtain one euploid blastocyst increased with age, as did the number of treatment cycles that did not get at least one euploid blastocyst. An adjusted multivariate binary regression model was designed using 80% of the patient group sample (n = 2,462; training set). A calculator for the probability of obtaining at least one euploid blastocyst was created using this model. The validation of this model in the remaining 20% of the patient group sample (n = 493; validation set) showed that it could estimate the event of having at least one euploid blastocyst with an accuracy of 72.0%.

Conclusions: Our results show a preliminary model capable of predicting the number of MII oocytes needed to obtain at least one euploid blastocyst according to female age, calculated with the largest database of IVF-PGT-A treatment cycles ever used for this purpose, including only treatment cycles using next-generation sequencing on trophoectoderm biopsies. Once this model has been properly validated, it could help with decision-making for both clinicians and patients coming to an infertility clinic.

Keywords: NGS; Oocyte; PGT-A; euploid blastocyst; female age.