Obstetric outcomes following vitrification of in vitro and in vivo matured oocytes

ObjectiveTo evaluate obstetric outcomes with oocyte vitrification after ovarian stimulation (OS) and in vitro maturation (IVM) of immature oocytes.DesignA prospective trial from October 2003 to April 2007.SettingUniversity-based medical center.Patient(s)OS group: 38 patients undergoing intrauterine insemination who overresponded to OS. IVM group: 20 patients who had previous unsuccessful intrauterine insemination.Intervention(s)Mature oocyte retrieval following OS. Immature oocyte retrieval and IVM. Oocyte vitrification, thawing, insemination, and transfer of the resulting embryos.Main Outcome Measure(s)Live-birth rates and obstetric outcomes.Result(s)The OS group was superior to the IVM group in terms of oocyte survival (81.4 ± 22.6% vs. 67.5 ± 26.1%), fertilization rate (75.6 ± 22.5% vs. 64.2 ± 19.9%), and cumulative embryo score (38.4 ± 22.3 vs. 20.0 ± 13.8). However, the differences in the implantation rate per embryo (19.1 ± 25.8% vs. 9.6 ± 24.1%), clinical pregnancy rate per cycle started (44.7%, vs. 20.0%), and live-birth rate per cycle started (39.5% vs. 20.0%) were not statistically significant. Twenty healthy babies were born in the OS group and four in the IVM group.Conclusion(s)Pregnancies achieved with vitrification of oocytes after OS and IVM treatments do not appear to be associated with adverse pregnancy outcomes. Vitrification of IVM oocytes represents a novel option for fertility preservation.