P-729 Factors affecting live birth rates in frozen-thawed single euploid blastocyst transfer cycles
Authors: Ozer G , Akca A , Bakır V L , Yelke H , Ozkara G , Kumtepe Colakoglu Y , Cetinkaya M , Tufekci M A , Kahraman S 
Published: June 2023

Study question

What are the factors affecting the rates of live birth in frozen-thawed euploid embryo transfer cycles?

Summary answer

Some demographic characteristics, frozen embryo transfer (FET) cycle parameters, and embryo characteristics of patients affect live birth rates in euploid embryo transfer cycles.

What is known already

The aim of assisted reproductive techniques (ART) is to achieve live birth as soon as possible. Preimplantation genetic testing (PGT) is an embryo selection technique recommended to shorten the live birth time. In addition, PGT reduces the number of failed ART cycles by eliminating embryos with chromosomal abnormalities that will not implant or will cause miscarriage. Despite these, the live birth rate after euploid embryo transfer cycles is still not at the expected level.

Study design, size, duration

This retrospective cohort study was conducted between January 2011 and May 2021 at the IVF and Reproductive Genetics Centre, Memorial Sisli Hospital, Istanbul, Turkey. The study involved a total of 2783 frozen-thawed euploid embryo transfer cycles.

Participants/materials, setting, methods

2873 euploid FET cycles were analysed in the study to determine factors affecting live birth rates. 30 parameters thought to affect live birth were identified and analysed by logistic regression analysis on the effects of live birth. These parameters include patients' demographics, fresh cycle and FET cycle characteristics, and embryo-related parameters on live birth effects in euploid embryo transfer cycles.

Main results and the role of chance

53% of 2783 euploid embryo transfer cycles have resulted in a live birth. The birth rate was 0,5 times less in the group with a body mass index (BMI) of higher than 29 compared to the group with a BMI of less than 25 (p &lt; 0.05). In cycles in which embryos of good-to-moderate-to-poor quality were transferred, the chance of live birth was lower than in cycles in which embryos of top quality were transferred (OR:0.837 OR:0.515 OR:0.528, respectively). The live birth rate was higher in cases where endometrial preparation was performed in natural cycles than in artificial cycles (OR:1.67, p &lt; 0.05). Embryo transfers without separate blastomeres had a higher live birth rate than embryo transfers with separate blastomeres (OR:1.416, p &lt; 0.006). The live birth rate was 0.7 times lower in the group that did not undergo embryo re-expansion 4 hours after thawing (p &lt; 0.04). Embryo transfer on the sixth day was associated with a lower live birth rate than embryo transfer on the fifth day. (OR:0.6, p &lt; 0.02). The group with a history of recurrent implantation failure (RIF) had a lower live birth rate than the group without a history of RIF (OR:0.5)

Limitations, reasons for caution

This study is a retrospective study.

Wider implications of the findings

In euploid embryo transfer cycles, clinicians and embryologists must know the parameters affecting live birth to guide treatment and select the embryo to be transferred first. In addition, the patient should be informed and guided about these factors.

Trial registration number

Not applicable