RESCUE-IVM AND THE TRANSFER OF A EUPLOID BLASTOCYST PROVIDED IMPROVED ODDS FOR PATIENTS WITH POOR PROGNOSIS TO CONCEIVE

Abstract

Rescue in vitro maturation (Rescue-IVM) of immature oocytes in stimulation cycles may generate additional embryos for transfer and increase changes of pregnancy for patients with poor prognosis. However, rescue-IVM oocytes are inevitably matured in the absence of cumulus cells. Therefore, the safety of performing rescue-IVM is questionable, as it may increase the chance of meiotic defects and miscarriage. To evaluate the safety of rescue-IVM, we retrospectively analyzed the pregnancy outcome of euploid blastocyst transfer with only embryos produced from rescue-IVM. Following routine ovarian stimulation and oocyte retrieval, immature oocytes at the germinal vesicle (GV) or metaphase I (MI) stage were placed into Oocyte Handling Medium for Maturation (OHM-Mat) for 27-30 h. ICSI was performed on all MII oocytes that matured by the second day following rescue-IVM, and cultured to the blastocyst stage for trophectoderm biopsy and PGT-A prior to vitrification. A total of 418 good quality blastocysts (≥Grade 3BB) from infertility patients with mean maternal age 36.6 ± 3.5 years and mean paternal age 39.2 ± 6.0 years, were produced from rescue-IVM. A significantly lower embryonic euploid rate was observed in the rescue-IVM group compared to blastocysts produced from MII oocytes collected at the time of retrieval in a maternally age matched cohort (n=1732) (42.1% and 55.9%, respectively, p<0.0001). A total of 58 frozen embryo transfers were performed with rescue-IVM only euploid blastocysts and yielded 81.0% positive bhCG, 70.7% clinical pregnancy with fetal cardiac activity, 67.2% live birth and only a miscarriage rate of 4.9%. These rates were comparable to the cohort of maternally aged matched women with MII oocytes collected at the time of retrieval (84.8% positive bhCG, 72.9% clinical pregnancy with fetal cardiac activity, 68.9% live birth, and 5.5% miscarriage). Rescue-IVM may induce oocyte meiotic defects resulting in a higher percentage of aneuploid blastocysts. However, euploid blastocysts produced by rescue-IVM are equally competent yielding implantation and live birth rates comparable to their maternally aged counterparts with mature MII oocytes at the time of oocyte retrieval.