Dataset Information

Association of Fresh Embryo Transfers Compared With Cryopreserved-Thawed Embryo Transfers With Live Birth Rate Among Women Undergoing Assisted Reproduction Using Freshly Retrieved Donor Oocytes.

ABSTRACT:

Importance

In in vitro fertilization cycles using autologous oocytes, data have demonstrated higher live birth rates following cryopreserved-thawed embryo transfers compared with fresh embryo transfers. It remains unknown if this association exists in cycles using freshly retrieved donor oocytes.

Objective

To test the hypothesis that in freshly retrieved donor oocyte cycles, a fresh embryo transfer is more likely to result in a live birth compared with a cryopreserved-thawed embryo transfer.

Design, setting, and participants

Retrospective cohort study using national data collected from the Society for Assisted Reproductive Technology for 33 863 recipients undergoing fresh donor oocyte cycles in the US between January 1, 2014 and December 31, 2017.

Exposures

Fresh embryo transfer and cryopreserved-thawed embryo transfer.

Main outcomes and measures

The primary outcome was live birth rate; secondary outcomes were clinical pregnancy rate and miscarriage rate. Analyses were adjusted for donor age, day of embryo transfer, use of a gestational carrier, and assisted hatching.

Results

Recipients of fresh and cryopreserved-thawed embryos had comparable median age (42.0 [interquartile range {IQR}, 37.0-44.0] years vs 42.0 [IQR, 36.0-45.0] years), gravidity (1 [IQR, 0-2] vs 1 [IQR, 0-3]), parity (0 [IQR, 0-1] vs 1 [IQR, 0-1]), and body mass index (24.5 [IQR, 21.9-28.7] vs 24.4 [IQR, 21.6-28.7]). Of a total of 33 863 recipients who underwent 51 942 fresh donor oocyte cycles, there were 15 308 (29.5%) fresh embryo transfer cycles and 36 634 (70.5%) cryopreserved-thawed embryo transfer cycles. Blastocysts were transferred in 92.4% of fresh embryo transfer cycles and 96.5% of cryopreserved-thawed embryo transfer cycles, with no significant difference in the mean number of embryos transferred. Live birth rate following fresh embryo transfer vs cryopreserved-thawed embryo transfer was 56.6% vs 44.0% (absolute difference, 12.6% [95% CI, 11.7%-13.5%]; adjusted relative risk [aRR], 1.42 [95% CI, 1.39-1.46]). Clinical pregnancy rates were 66.7% vs 54.2%, respectively (absolute difference, 12.5% [95% CI, 11.6%-13.4%]; aRR, 1.34; [95% CI, 1.31-1.37]). Miscarriage rates were 9.3% vs 9.4%, respectively (absolute difference, 0.2% [95% CI, -0.4% to 0.7%]); aRR, 0.98 [95% CI, 0.91-1.07]).

Conclusions and relevance

In this retrospective cohort study of women undergoing assisted reproduction using freshly retrieved donor oocytes, the use of fresh embryo transfers compared with cryopreserved-thawed embryo transfers was associated with a higher live birth rate. However, interpretation of the findings is limited by the potential for selection and confounding bias.

SUBMITTER: Insogna IG

PROVIDER: S-EPMC7804915 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background: The availability and use of frozen-thawed embryos after controlled ovarian hyperstimulation for assisted reproduction have increased with improvements in vitrification techniques and the rise of gonadotropin-releasing hormone (GnRH) antagonist protocols. Although evidence has shown that frozen-thawed embryo transfers (FETs) result in higher live birth rates than fresh embryo transfers, it is uncertain whether this association exists in cycles employing the GnRH antagonist protocol. Objective: To test the hypothesis that FETs are more likely to result in a live birth than fresh embryo transfers in a GnRH antagonist protocol cycle and to investigate whether frozen blastocyst transfer increases live birth rates compared to fresh blastocyst transfer. Design: A retrospective historical cohort study was conducted using data collected from the Department of Reproductive Medicine of Liuzhou Maternity and Child Healthcare Hospital for 1,437 patients who underwent the GnRH antagonist protocol between 1 January 2015, and 31 December 2020. The primary outcome was the live birth rate, which was compared between fresh embryo transfer and FET, and the secondary outcomes were clinical pregnancy rate and miscarriage rate, which were compared between the two groups. Analyses were adjusted to account for the age of the patient, number of embryo transfers, day of embryo transfer, and type of infertility. Results: Fresh embryo transfers accounted for 1,026 (71.4%) of the 1,437 patients who underwent the GnRH antagonist protocol in our analysis, while FETs accounted for 411 (28.6%). Patients with fresh and frozen-thawed embryos had comparable median body mass index (body mass index; 22.3 [IQR, 24.6-20.0] vs. 22.0 [IQR, 24.5-19.9]). There was a significant difference in the median age of the fresh embryo transfer group (34.0 [IQR, 39.0-30.0]) and the Frozen-thawed embryo transfer group (32.0 [IQR, 37.0-29.0]). Blastocysts were transferred in 14.6% of the fresh embryo transfer cycles and 45.5% of the FET cycles, whereas they account for 10.4% and 13.0% of all patients, respectively. The mean number of embryos transferred was 2 (IQR, 2.0-1.0) for the fresh embryo transfer group and 1 (IQR, 2.0-1.0) for the FET group, with a significant difference in the mean number of embryos transferred. The live birth rate after fresh embryo transfer vs. FET was 28.7% vs. 34.5% (absolute difference, 5.9%; adjusted relative risk [aRR], 1.15 [95% CI, 0.88-1.51]). The clinical pregnancy rates were 39.9% vs. 46.0%, respectively (absolute difference, 6.1%; aRR, 1.10 [95% CI, 0.85-1.43]). The miscarriage rates were 22.5% vs. 23.8%, respectively (absolute difference, 1.3%; aRR, 1.13 [95% CI, 0.75-1.70]). Conclusion: In this retrospective study of women who underwent assisted reproduction using GnRH antagonists, FETs resulted in a higher live birth rates and clinical pregnancy rates than fresh embryo transfers, which parts of these differences were attributable to embryo stage. However, the interpretation of the findings is limited by the possibility of selection and confounding biases.