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

Objective: To evaluate obstetric outcomes with oocyte vitrification after ovarian stimulation (OS) and in vitro maturation (IVM) of immature oocytes.

Design: A prospective trial from October 2003 to April 2007.

Setting: University-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.