The Human Oocyte Preservation Experience (HOPE) Registry: evaluation of cryopreservation techniques and oocyte source on outcomes.

Background: This prospective, Phase IV, multicenter, observational registry of assisted reproductive technology clinics in the USA studied outcomes of first cycles using thawed/warmed cryopreserved (by slow-freezing/vitrification) oocytes (autologous or donor).

Methods: Patients were followed up through implantation, clinical pregnancy, and birth outcomes. The main outcome measure was live birth rate (LBR), defined as the ratio of live births to oocytes thawed/warmed minus the number of embryos cryopreserved for each cycle, averaged over all thawing cycles. Clinical pregnancy rate (CPR) was also evaluated, and was defined as the presence of a fetal sac with heart activity, as detected by ultrasound scan performed on Day 35-42 after embryo transfer.

Results: A total of 16 centers enrolled 204 patients; data from 193 patients were available for analyses. For donor oocytes, in the slow-freezing (n = 40) versus vitrification (n = 94) groups, respectively, CPR and LBR were significantly different: 32.4% versus 62.6%, and 25.0% versus 52.1%; outcomes from Day 3 transfers did not differ significantly. For vitrified oocytes, in the autologous (n = 46) versus donor (n = 94) group, respectively, CPR and LBR were significantly different: 30.0% versus 62.6% and 17.4% versus 52.1%. This was largely due to a significant difference in CPR with Day 5/6 transfers.

Conclusions: In two subgroup data analyses, in women who received cryopreserved oocytes from donors, CPR and LBR were significantly higher in cycles using oocytes cryopreserved via vitrification versus slow-freezing, reflecting differences in methodologies and more Day 5/6 transfers; in women who received vitrified oocytes, CPR and LBR were significantly higher in cycles using donor versus autologous oocytes with Day 5/6 transfers.

Trial Registration: ClinicalTrials.gov: NCT00699400 . Registered June 13, 2008.