A comparison of live birth rates and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos

Purpose Prior studies suggest that pregnancy outcomes after autologous oocyte cryopreservation are similar to fresh in vitro fertilization (IVF) cycles. It is unknown whether there are differences in pregnancy and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos. This is a retrospective cohort study comparing pregnancy and perinatal outcomes between oocyte and embryo cryopreservation at a university-based fertility center. We included 42 patients and 68 embryo transfers in patients who underwent embryo transfer after elective oocyte preservation (frozen oocyte-derived embryo transfer (FOET)) from 2005 to 2015. We compared this group to 286 patients and 446 cycles in women undergoing cryopreserved embryo transfer (frozen embryo transfer (FET)) from 2012 to 2015. Five hundred fourteen transfer cycles were included in our analysis. The mean age was lower in the FOET vs FET group (34.3 vs 36.0 years), but there were no differences in ovarian reserve markers. Thawed oocytes had lower survival than embryos (79.1 vs 90.1%); however, fertilization rates were similar (76.2 vs 72.8%). In the FOET vs FET groups, clinical pregnancies were 26.5 and 30%, and live birth rates were 25 and 25.1%. Miscarriages were higher in the FET group, 8.1 vs 1.5%. There were no differences in perinatal outcomes between the two groups. The mean gestational age at delivery was 39.1 vs 38.6 weeks, mean birth weight 3284.2 vs 3161.1 gms, preterm gestation rate 5.9 vs 13.4%, and multiple gestation rate 5.9 vs 11.6%. In our study, live birth rates and perinatal outcomes were not significantly different in patients after oocyte and embryo cryopreservation.