Controlled ovarian hyperstimulation (COH) parameters associated with euploidy rates in donor oocytes

Although oocyte donors are young and are expected to provide a high rate of euploid oocytes, significant differences of euploidy rates for donor embryos exist between different IVF centers (1). Laboratory conditions can lead to differences of euploidy (2,3,4,5,6,7); but, the role of COH has not been investigated. In this study, we investigated whether euploidy rates in the embryos created from donor oocytes are influenced by controlled ovarian hyperstimulation parameters used during assisted reproduction. Euploidy rates in egg donor cycles undergoing PGT-A (N = 423) were examined retrospectively for associations with donor age, gonadotropin doses (dose per day), the fraction of gonadotropin provided by hMG (F(hMG)), days of stimulation, estradiol per mature oocyte on day of trigger, number of mature oocytes retrieved, number of embryos biopsied, incidence of euploidy and physician of record. Differences in euploidy rates between physicians were examined using analysis of variance. The proportion of euploid embryos per donor cycle was examined for associations with COH parameters using pairwise post-hoc comparisons, adjusting for multiple testing. The set of variables from this analysis was then submitted to a principal component analysis. Linear regression analysis was used to assess the relationships between stimulation parameters and the incidence of euploidy (the dependent variable). Euploidy rates and cycle parameters varied significantly among treating physicians. Euploidy rates (expressed as a fraction of biopsied embryos) were associated (p = 0.01) only with the F(hMG) but not with the number of MII retrieved or other variables. On the other hand, the number of euploid embryos (in contrast to the euploidy rate) was associated with the number of MII produced. Donor euploidy rates are significantly associated with the fraction of total gonadotropin comprising human menopausal gonadotropin (or F(hMG)) during controlled ovarian hyperstimulation but are not associated with other cycle parameters. The study provides the first suggestion that patient stimulation parameters can affect the incidence of euploidy in embryos generated through the use of standard assisted reproductive techniques. The study is limited by its retrospective approach and because the aCGH analysis used is less sensitive than more recent NGS technology. Further, it provides a suggestion that the use of hMG is beneficial for obtaining euploid embryos.