Impact of vitrification on human oocytes before and after in vitro maturation (IVM): A systematic review and meta-analysis

Background: Combination of in vitro maturation (IVM) and cryopreservation offers new opportunities for women with contraindication in ovarian stimulation, and females who desire to postpone the childbearing due to different problems. There are still controversies regarding IVM procedure and its impact on oocytes fertilization capability.Objective: The aim of this systematic review and meta-analysis was to evaluate the impact of vitrification on human oocytes during IVM procedure.Materials and Methods: A systematic review with meta-analysis was undertaken. Main search terms were those related key words. We searched Medline, Embase, Scopus and ISI web of science to detect English-language studies. The original articles which studied ART outcomes after vitrification of MII or GV oocytes before or after IVM were included. Studies that compared the combination of vitrification and IVM with fresh oocytes were also included. Exclusion criteria were animal trials and the studies that performed cryopreservation using slow-freeze method. The protocol of the review has been registered in the International Prospective Register of Systematic Reviews (PROSPERO) by registration number of CRD42017054372.Results: 2476 articles were screened and after duplicates removing together with the application of inclusion and exclusion criteria, 14 studies assessed for eligibility. Finally, 5 studies included for analysis. All studies compared laboratory outcomes between oocytes that vitrified at the GV stage and those which firstly matured in vitro, and then vitrified. Meta-analysis showed that vitrification of oocytes at GV stage had a negative impact on maturation rate (RR=1.28, 95% CI: 0.96-1.70); but not on cleavage rate (RR=1.07, 95% CI: 0.70-1.64); fertilization rate (RR=0.99, 95% CI: 0.85-1.14) and survival rate (RR=1.01, 95% CI: 0.96-1.06).Conclusion: In general, based on our results, oocyte vitrification decreases the maturation rate. In addition, survival, fertilization as well as cleavage rates did not significantly differ between the oocytes vitrified before IVM versus oocytes vitrified after IVM. However, there was no significant difference in oocyte maturation rate regarding vitrification before and after IVM.

کلیدواژه ها:

Human oocyte Vitrification ، in vitro maturation ، Cryopreservation ، Fertility Preservation