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. 2020 Mar 11;19(2):182-188.
doi: 10.1002/rmb2.12322. eCollection 2020 Apr.

Predictive factors influencing pregnancy rate in frozen embryo transfer

Nao Hayashi  1 , Noritoshi Enatsu  1 , Toshiro Iwasaki  1 , Junko Otsuki  1   2 , Yukiko Matsumoto  1 , Shoji Kokeguchi  1 , Masahide Shiotani  1
Affiliations

Predictive factors influencing pregnancy rate in frozen embryo transfer

Nao Hayashi et al. Reprod Med Biol. .

Abstract

Purpose: To evaluate the outcomes of embryo transfer (ET) and to identify the parameters influencing pregnancy outcomes.

Methods: This study included 938 ET cycles involving single frozen and thawed good-quality blastocyst (Gardner grade ≥3BB) between August 2017 and January 2018. The significance of several parameters including endometrial thickness, position of the transferred air bubble, self-evaluation score by physicians, and uterus direction at ET as predictors of clinical pregnancy was evaluated using univariate and multivariate analyses.

Results: Among 938 ET cycles, 462 (49.3%) resulted in a clinical pregnancy. Endometrial thickness was positively associated with clinical pregnancy in a linear trend. Between the variable position of the transferred air bubble and clinical pregnancy rate showed a curvilinear relationship. Clinical pregnancy rate was higher in cases with good self-evaluation score, whereas there was no difference between groups with different uterus directions. Univariate analysis of predictive parameters identified endometrial thickness, self-evaluation score by physicians, and position of air bubbles as significant predictors of clinical pregnancy, of which endometrial thickness and position of air bubbles appeared to be independently related to clinical pregnancy.

Conclusion: Endometrial thickness and the position of transferred air bubbles influenced clinical pregnancy in ET cycles.

Keywords: assisted reproductive technique; clinical pregnancy rate; endometrial thickness; frozen‐thawed embryo transfer; predictive factors.

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Conflict of interest statement

Conflict of interest: Nao Hayashi, Noritoshi Enatsu, Toshiro Iwasaki, Junko Otsuki, Yukiko Matsumoto, Shoji Kokeguchi, Masahide Shiotani declare that they have no conflict of interest. Human rights statement and informed consent: All patients were well informed, and written informed consent was obtained prior to the treatment period. The treatment investigated in this study has already been discussed in other studies that have shown positive outcomes. Animal studies: This article contains no studies with animal subjects performed by any of the authors. Approval by Ethics Committee: This study was approved by Ethical Committee of Hanabusa Women's Clinic consists of members chosen by our institute and third party medical institute (approval number; 2019‐08).

Figures

Figure 1
Figure 1
A, Scatter plot and linear correction for clinical pregnancy rates and endometrial thickness showing a positive correlation and a linear trend. B, Receiver operator characteristic curve constructed for the assessment of endometrial thickness and clinical pregnancy by frozen‐thaw embryo transfer. A clinical threshold was calculated when sensitivity plus specificity reached maximum
Figure 2
Figure 2
Scatter plot and non‐linear correction describing a curvilinear relationship between the variable position of the transferred air bubble and clinical pregnancy. This graph indicates that the clinical pregnancy rate increased as the air bubble position got closer to 6 mm apart from uterine fundus, remained steady until 10 mm, and began decreasing after 10 mm
Figure 3
Figure 3
Association between clinical pregnancy rate and self‐assessment relating “A” or “B/C”
Figure 4
Figure 4
Association between pregnancy rate and uterus direction. Statistical differences are analyzed by chi‐square test of 3 × 2 contingency table
See this image and copyright information in PMC

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