Clinical outcomes after fresh versus frozen embryo transfer in women with advanced reproductive age undergoing in vitro fertilization: a propensity score-matched cohort study

Abstract

This retrospective cohort study aimed to compare clinical outcomes following fresh or frozen embryo transfer (FET) in women with advanced reproductive age (ARA). Women aged 35–45 years who underwent their first autologous fresh or frozen cleavage stage embryo transfer cycle in the Centre for Assisted Reproduction of Shanghai First Maternity and Infant Hospital between January 2016 and December 2020 were included. The primary outcome was live birth after the first embryo transfer of the in vitro fertilization (IVF) cycle. Multiple covariates were used for propensity score matching (PSM) and generalized estimating equations were performed to examine the independent association between FET and live birth. Of the total 1453 patients, 327 patients had FET and 1126 patients had fresh ET. After the PSM procedure, 274 patients were included in each group. The live birth rate was 24.8% in the FET group and 25.2% in the fresh ET group (OR 0.98, 95% CI: 0.67–1.44, P = 0.92). Other pregnancy, perinatal and neonatal outcomes were all comparable between the two groups. This study showed that FET did not improve live birth and other clinical outcomes as compared with fresh embryo transfer in women with ARA who underwent their first IVF cycle.

Keywords:

• Frozen embryo transfer
• in vitro fertilization
• women with advanced reproductive age
• live birth
• propensity score matching

Acknowledgements

The authors thank Marilyn Seidel for her excellent proofreading.

Ethics approval

This study was approved by the Research Ethics Committee of Shanghai First Maternity and Infant Hospital (KS21211).

Author contributions

CYS, MMY and YYW collected data, analyzed data and wrote the manuscript. QYC, ZZM and LLG contributed to analysis and interpretation of data. OB and BWM revised the manuscript. XMT contributed to study supervision and interpretation of data. MXC designed the study, analyzed data and revised the manuscript. All authors reviewed and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a grant from the Special Funds for Clinical Medical Research of Chinese Medical Association [18010030732], a grant from the Science and Technology Commission of Shanghai Municipality [19411960500], a grant from the Clinical Research Plan of Shanghai Hospital Development Center [SHDC2020CR4080], two grants from the National Natural Science Foundation of China [81871213,81671468], a grant from the State’s Key Project of Research and Development Plan [SQ2017ZY050118-03], and a grant from the Shanghai Municipal Population and Family Planning Commission [201640364]. Ben W. Mol is supported by a NHMRC Investigator grant (GNT1176437). Ben W. Mol reports consultancy for ObsEva, and research grants from Merck KGaA, Ferring and Guerbet. The funding bodies have not participated in the design of the study and collection, analysis, interpretation of data or in writing the manuscript.