FRESH EMBRYO TRANSFER IMPROVES LIVE BIRTH RATE OVER FROZEN EMBRYO TRANSFER IN FRESHLY RETRIEVED DONOR EGG CYCLES

Abstract

To test the hypothesis that in cycles using embryos derived from freshly retrieved donor eggs, a fresh embryo transfer (fresh ET) is more likely to result in a clinical pregnancy and live birth compared to a cryopreserved-thawed embryo transfer (CET). Retrospective cohort study using national data from the Society for Assisted Reproductive Technology (SART). Donor egg cycles in the SART database from 2014-2017 were collected. Only cycles using freshly retrieved eggs from anonymous donors were included. Cycles in which eggs were previously frozen, a known donor was used, or recipient age at time of transfer was over 55 years were excluded. All included cycles had at least one embryo available to transfer at either the cleavage or blastocyst stage. Using log binomial regression, relative risks and 95% confidence intervals were calculated for clinical pregnancy rate (CPR), live birth rate (LBR) and miscarriage rate. Crude and adjusted analyses were performed, controlling for donor age. Of a total of 51,942 donor egg cycles, 15,308 (29.5%) were fresh ET cycles and 36,634 (70.5%) were CET cycles. Both groups were similar in terms of age, gravidity, parity, BMI, infertility diagnosis, and race/ethnicity. A majority of recipients had blastocyst(s) transferred (92.4% of fresh ETs and 96.5% of CETS), with a similar mean number of embryos transferred: 1.52 ± 0.52 in the fresh and 1.39 ± 0.53 in the CET groups. Both CPR and LBR were lower after CET compared to fresh ET (CPR 54.2% vs 66.7%, aRR 0.78 [95% CI 0.76-0.79]; LBR 44.0% vs 56.6%, aRR 0.74 [95% CI 0.72-0.75]), controlled for donor age. Miscarriage rate was similar for both (9.4% following CET vs 9.3% following fresh ET, aRR 1.02 [95% CI 0.96-1.10]). CPR and LBR following transfer of fresh non-PGT-A embryos were statistically significantly higher than following transfer of PGT-A embryos (either fresh or frozen) with no difference in miscarriage rates (Table).Tabled 1Fresh non-PGT-AN = 15044Fresh and frozen PGT-AN = 2327Frozen PGT-AN = 2063RR (95% CI)aRR (95% CI)*RR (95% CI) ‡aRR (95% CI) * ‡Clinical pregnancy10026 (66.6%)1420 (61.0%)1237 (60.0%)0.92 (0.88-0.95)0.89 (0.85-0.94)0.90 (0.87-0.93)0.84 (0.79-0.90)Live birth8505 (56.5%)1191 (51.2%)1031 (50.0%)0.91 (0.87-0.94)0.89 (0.83-0.95)0.88 (0.84-0.93)0.82 (0.75-0.89)Miscarriage1396 (9.3%)203 (8.7%)183 (8.9%)0.94 (0.82-1.08)0.94 (0.76-1.17)0.96 (0.83-1.11)1.01 (0.80-1.29)* adjusted for donor age. ‡ relative risk for only frozen PGT-A compared to fresh non-PGT-A Open table in a new tab * adjusted for donor age. ‡ relative risk for only frozen PGT-A compared to fresh non-PGT-A Both CPR and LBR following the use of fresh donor eggs are over 10% higher after a fresh rather than frozen embryo transfer. This study suggests that recipients should be encouraged to undergo fresh donor egg embryo transfer without PGT-A.