JBRA Assist. Reprod. 2025;29(Suppl 1):51-51
POSTER PRESENTATION
doi: 10.5935/1518-0557.20250105
P-037. Frozen Single Euploid Embryo Transfer and Endometrial Preparation: Natural Cycle vs. Artificial Cycle
1Clínica CEM, Montevideo, Uruguay
Objective: Numerous studies have reported implantation rates of cryopreserved euploid embryos ranging from 61% to 70%(Tian et al., 2024; Forman et al., 2013; Sánchez-González et al., 2020; Kemper et al., 2020; Sociedad Española de Fertilidad. 2021). However, does this success depend on the protocol used for endometrial preparation in frozen embryo transfer (FET)? This study aims to compare the ongoing pregnancy rates between natural and artificial endometrial preparation cycles in single euploid embryo transfers.
Methods: A retrospective cross-sectional study was conducted to compare implantation and live birth rates following a FET of one euploid embryo in two groups:
- Natural cycle (NC): endometrial preparation without exogenous estrogen.
- Artificial cycle (AC): endometrial preparation with 6 mg/day of estradiol valerate.
Both groups received vaginal progesterone supplementation (800 mg/day), and serum progesterone levels were measured on the day of embryo transfer.The analysis included women who underwent euploid embryo FET between January 2022 and December 2023. All embryos were day 5 or 6 blastocysts that had undergone PGT-A. Mosaic embryos were excluded. Serum β-hCG was measured on day 10 posttransfer, and clinical pregnancy was confirmed by ultrasound scan at 6 weeks of gestation.
Results: A total of 193 single euploid FETs were included, with maternal age at cryopreservation ranging from 28 to 48 y.o (mean age 38.3 years overall).103 transfers were performed in NC with 66 positive BhCG and 59 ultrasound scan positive pregnancies. 56 pregnancies resulted in live birth and 3 in spontaneous abortion. In AC there were 90 transfers, 50 positive BhCG, and 42 ultrasound scan positive pregnancies. 35 resulted in live births and 6 in spontaneous abortion. One ectopic pregnancy was reported (table 1). Live birth rates were significantly higher in the natural endometrial preparation group (p=0.0294). While biochemical pregnancies and spontaneous miscarriages were more frequent in the artificial cycle group, the difference was not statistically significant (p=0.1550).
Conclusion: Based on our study conducted at Clínica CEM in Montevideo, our conclusion is that natural endometrial preparation cycles are associated with better live birth rates compared to artificial endometrial preparation cycles. These findings support the recommendation of natural cycle endometrial preparation to enhance clinical outcomes.
Table 1.
References
Forman et al. Fertil Steril. 2013l;100:100-7.e1.
Kemper, Hum Reprod. 2020;35:2408-12
Sánchez-González et al. Ginecol. obstet. Méx. 2020; 88: 508-16.
Sociedad Española de Fertilidad. Registro Nacional de Actividad 2021