P–151 Correlation between the first euploid frozen-thawed blastocyst embryo transfer (FBT) and the subsequent euploid FBT outcome originating from the same cohort of oocytes
Authors: Abalı R , Boynukalın F K , Gültomruk M , Yarkiner Z , Bahçeci M 
Published: August 2021

Abstract

Study question
Does the outcome of the first euploid frozen-thawed blastocyst embryo transfer affect the subsequent euploid FBT originating from the same cohort of oocytes?

Summary answer
The clinical pregnancy rate and ongoing pregnancy rate of the subsequent FBT are higher if a clinical pregnancy was attained in the first euploid FBT.

What is known already
Numerous factors including patient, cycle and embryological characteristics affect the outcome of an IVF treatment cycle. There is no data available whether the outcome of euploid FBT has an impact on the outcome of the subsequent euploid FBT of embryos originating from the same cohort of retrieved oocytes.

Study design, size, duration
The study enrolled cycles preimplantation genetic test for aneuploidy (PGT-A) performed between January 2016 and July 2019 at the Bahceci Fulya IVF Center. A total of 1051 patients with single euploid FBT were evaluated and resulted live birth (n = 589, live birth rate (LBR): 56%(589/1051)), miscarriage (n = 100, miscarriage rate (MR): 14.5% (100/689)) and no clinical pregnancy (n = 362, 34,4%, (362/1051)). 159 FBT after the first single euploid FBT originating from the same cohort of oocytes were analyzed.

Participants/materials, setting, methods
Second euploid FBT cycle after first FBT with a clinical pregnancy were compared to frozen-thawed cycles after a without a pregnancy. Logistic regression analysis was utilized to adjust for potential confounders including female age, body mass index, embryo quality, day of embryo frozen, number previous failed attempt, number of previous miscarriage, endometrial thickness, outcome of the first euploid FBT.

Main results and the role of chance
The pregnancy outcome from the first euploid FBT in the study group was resulted live birth (25.1%, (40/159)), miscarriage (15.7%, (25/159)) and no clinical pregnancy (59.1%, (94/159). The pregnancy outcome of the subsequent euploid embryo transfer from the same oocyte cohort was clinical pregnancy rate (CPR): (67.3%, (107/159) ongoing pregnancy rate (OPR) (52.2% (83/159) and MR (22.4%, (24/107)). The CPR in the subsequent euploid FBT was 80% (52/65) among patients who achieved a clinical pregnancy in the first euploid FBT and 58.5% (55/94) of those who did not (p = 0.0045). The OPR in the subsequent euploid FBT was 64.6% (42/65) among patients who achieved a clinical pregnancy in first euploid FBT and 43.6% (41/94) of those who did not (p = 0.009). On a multivariate regression analysis, clinical pregnancy in the first euploid FBT was a significant independent predictor for a pregnancy in the subsequent FBT transfer (p = 0.003).

Limitations, reasons for caution
The limitation of the study is in the retrospective nature of the study. As the PGT-A strategy significantly decreases number of transferable embryos, the sample size of the study is limited.
Wider implications of the findings: Identifying predictive factors for the success of euploid FBT is important. These can help physicians while counseling patients regarding the outcome of the previous euploid FBT.

Trial registration number
NA