The influence of day 3 embryo cell number on the clinical pregnancy and live birth rates of day 5 single blastocyst transfer from frozen embryo transfer cycles.

Publisher: BioMed Central Country of Publication: England NLM ID: 100967799 Publication Model: Electronic Cited Medium: Internet ISSN: 1471-2393 (Electronic) Linking ISSN: 14712393 NLM ISO Abbreviation: BMC Pregnancy Childbirth Subsets: MEDLINE

Original Publication: London : BioMed Central, [2001-

Birth Rate* ; Cryopreservation*/methods; Pregnancy ; Female ; Humans ; Retrospective Studies ; Embryo Transfer/methods ; Pregnancy Rate ; Live Birth ; Cell Count

Background: To evaluate the influence of day 3 embryo cell number on the clinical pregnancy and live birth rates of day 5 single blastocyst transfer in frozen embryo transfer (FET) cycles.
Methods: Our retrospective study included 3761 day 5 single blastocyst FET cycles between January 2015 and December 2019. These FET cycles were divided into three groups according to the day 3 embryo cell number: 939 cycles in the < 8-cell group, 1224 cycles in the 8-cell group and 1598 cycles in the > 8-cell group. The clinical pregnancy and live birth rates were compared among the three groups.
Results: The clinical pregnancy rate of day 5 single blastocyst transfer in FET cycles increased significantly as the day 3 embryo cell number increased (52.2%, 61.4% and 66.8%, P < 0.001). Similarly, the live birth rate increased significantly as the day 3 embryo cell number increased (42.7%, 49.8% and 54.9%, P < 0.001). The results of the subgroup analysis showed that the clinical pregnancy and live birth rates were not significantly different among the three groups when good-quality blastocysts were transferred. The clinical pregnancy and live birth rates increased significantly as the day 3 embryo cell number increased when fair- and poor-quality blastocysts were transferred.
Conclusion: The day 3 embryo cell number needs to be considered when day 5 single blastocyst transfer is performed in FET cycles, especially when fair- and poor-quality blastocysts are used for transfer. The transfer of a day 5 single blastocyst derived from an embryo with faster development on day 3 may shorten the time to achieving a live birth.
(© 2022. The Author(s).)

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YKK15070 the Nanjing Medical Science and Technology Development Foundation

Keywords: Blastocyst; Clinical pregnancy; Embryo; Frozen embryo transfer; Live birth

Date Created: 20221229 Date Completed: 20230102 Latest Revision: 20230103

20240829

PMC9798545

10.1186/s12884-022-05337-z

36581843