P-133 The best of the worst: analyze of outcome in artificial reproductive technologies (ART) fresh cycles with transfers of slow-growing embryos and expanded poor-quality blastocysts
Authors: Polumiskova A , Shishimorova M , Tevkin S , Jussubaliyeva T 
Published: June 2022

Study question

Fresh transfer of slow-growing embryos versus expanded poor-quality blastocysts, in case of absence of good-quality blastocysts on day 5: which is the optimal approach?

Summary answer

The clinical pregnancy rate (CPR), live birth rate (LBR) are significantly higher during expanded poor-quality blastocysts transfers. There’s no statistical difference in miscarriage rate (MR).

What is known already

Several studies show contradictory results about which blastocyst morphological parameter best predicts pregnancy outcomes in ART cycle. However, in clinical practice embryologists encounter in ART protocols with scheduled fresh embryo transfer the absence of expanded good-quality blastocysts on day 5. In this case, slow-growing embryos or poor-quality blastocysts could be chosen for transfer. Day 5 slow-growing embryos have low implantation potential in fresh ART cycles, it could be due to embryo-endometrial asynchrony. Also, the quality of further blastocyst remains unclear. Poor-quality blastocysts have a high aneuploidy rate and lower viability compared to good-quality blastocysts.

Study design, size, duration

This study included ART cycles with fresh embryo transfer on day 5, with selected group of patients under 40 years of age, between 2014 and 2019. Group A consisted of 619 cycles with slow-growing embryos transfer; group B included 88 cycles with expanded poor-quality blastocysts transfer; the control group counted 1501 cycles with a transfer of good-quality blastocysts. Group A had an average of 1,5 embryos transferred per patient, control group and group B 1,3.

Participants/materials, setting, methods

Embryos were cultured until day 5 and scored according to Gardner and Schoolcraft’s grading system. In group A, slow-growing embryos were transferred at the stage of morula and early blastocyst with a degree of expansion 1. In group B, expanded poor-quality blastocysts were scored as 3-6CB, 3-6BC, 3-6CC. In control group expanded good-quality blastocysts were scored as 3-6AA, 3-6AB, 3-6BA, 3-6BB.The cycles with donor gametes, surrogacy, and preimplantation genetic testing were excluded.

Main results and the role of chance

The main women’s age of group A, B and control group was 32,2 ± 4,2, 31,5 ± 4,7 and 32,6 ± 4,6 years respectively. The CPR, the ongoing pregnancy rate (OPR), the LBR and the implantation rate (IR) were significantly increased in the group B compared to the group A [34,0% (30/88) vs 17,7% (110/619); P &lt; 0,01], [21,6% (19/88) vs 11,9% (74/619); P = 0,012], [19,3% (17/88) vs 10,5% (65/619); P = 0,015] and [26,2% (31/118) vs 12,6% (119/946); P &lt; 0,01] respectively. There’s no statistical difference in the MR between group A and B [35,2% (42/119) vs 35,5% (11/31); P = 0,946]. The CPR, the OPR, the LBR and the IR were significantly higher in the control group compared to the group A and B [50,5% (758/1501); P &lt; 0,01], [41,6% (625/1501); P &lt; 0,001], [40,3% (605/1501); P &lt; 0,001] and [40,45% (849/2099); P &lt; 0,01]. The MR in the control group was almost two times lower compared to the group A and B [16,2% (138/849); P &lt; 0,01). Relationships between variables were assessed by Pearson's chi-squared test.

Limitations, reasons for caution

The study is limited due to the uneven distribution of patients in three groups and by a low number of participants in group B. The grading of blastocysts’ quality is also subjected to a human factor.

Wider implications of the findings

If in ART protocol with scheduled fresh embryo transfer have no expanded good-quality blastocysts, expanded poor-quality blastocysts could be chosen for transfer and slow-growing embryos should be cultured until day 6 with subsequent cryopreservation of blastocysts. Patients should be informed about elevated MR after the transfer of poor-quality blastocysts.

Trial registration number

Not applicable