Yeungnam Univ J Med.  2020 Jan;37(1):47-53. 10.12701/yujm.2019.00346.

Clinical factors that affect the pregnancy rate in frozen-thawed embryo transfer in the freeze-all policy

• Hwang SY
• Jeon EH
• Kim SC
• Joo JK

• KMID: 2501407
• DOI: http://doi.org/10.12701/yujm.2019.00346

Abstract

Background
This study was conducted to analyze clinical factors that can affect pregnancy rates in normal responders undergoing the freeze-all policy in in vitro fertilization.
Methods
We evaluated 153 embryo transfer cycles in 89 infertile women with normal response to controlled ovarian stimulation (COS). After COS, all embryos were cultured to the blastocyst stage, and good quality blastocysts were vitrified for elective frozen-thawed embryo transfer (FET). Clinical variables associated with COS and the results of COS and culture, including the number of retrieved oocytes, fertilized oocytes, and frozen blastocysts were compared between the pregnant group and the non-pregnant group.
Results
After a single cycle of COS for each patient, 52 patients became pregnant while 37 did not. Significant differences were observed in the number of matured oocytes, fertilized oocytes, frozen blastocysts, and transferred embryos. The number of frozen blastocysts in the pregnant group was almost twice that in the non-pregnant group (5.6±3.1 vs. 2.8±1.9, p<0.001). The area under the receiver operating characteristic curve for the 4 frozen blastocysts was 0.801 in the pregnant group.
Conclusion
In the freeze-all policy, the number of matured oocytes, number of fertilized oocytes, and number of frozen blastocysts might be predictive factors for pregnancy.

Keyword

Blastocyst; Embryo transfer; In vitro fertilization; Pregnancy

Figure

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  Fig. 1. Flow diagram of the inclusion cycles. In this study, 153 embryo transfer cycles in 89 infertile women were analyzed. The second FET cycle was conducted in 50 patients and the third FET cycle was conducted in 14 patients. In case of no remnant frozen embryos, a second COS was started. FET, frozen-thawed embryo transfer; COS, controlled ovarian stimulation.

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  Fig. 2. ROC curve of the cumulative pregnancy group (A) and the pregnancy group after the first frozen embryo transfer (B). (A) AUC of the ROC curve of the cumulative pregnancy group: 0.801 for the 4 frozen blastocysts (95% CI, 0.625–0.819), 0.713 for the 13 fertilized oocytes (95% CI, 0.540–0.747), and 0.710 for the 8 matured oocytes (95% CI, 0.525–0.733). (B) AUC of the ROC curve of the pregnancy group for the first frozen embryo transfer: 0.730 for the 4 frozen blastocysts (95% CI, 0.588–0.788), 0.649 for the 13 fertilized oocytes (95% CI, 0.548–0.753), and 0.634 for the 14 matured oocytes (95% CI, 0.524–0.733). ROC, receiver operating characteristic; AUC, area under curve; CI, confidence interval.

Reference

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