The impact of embryo quality and endometrial thickness on frozen embryo transfer cycles
DOI:
https://doi.org/10.18203/2320-1770.ijrcog20260548Keywords:
Endometrial thickness, Embryo grading, Euploid embryo transfer, Implantation rateAbstract
Background: Endometrial thickness and embryo quality are critical factors influencing implantation rates in IVF cycles. This study aimed to study how endometrial thickness impacts implantation rate in FET cycles and study the relationship between the quality of the transferred embryos and the occurrence of successful pregnancy.
Methods: This study retrospectively analyzed 100 embryo transfer cycles that were performed in fertility centers associated with SPOVUM TECHNOLOGIES PRIVATE LIMITED, Rajajinagar, Bangalore. ET assessment was performed with grayscale ultrasound on the day of embryo transfer. Embryo grading ranked embryos based on morphological features of each embryo indicating its viability and developmental potential.
Results: Out of 100 patients, successful pregnancy was achieved in 56 patients, giving implantation rate of 56% (56/100). Patients with endometrial thickness (ET) <9 mm on the day of embryo transfer had significantly lower implantation rates compared to those with ET ≥9 mm (p = 4.68 × 10⁻⁵). Implantation rates by embryo grade were 65% for excellent, 60% for fair, and 14% for poor-grade embryos. Higher implantation rates were observed following transfer of blastocysts with Grade A and B trophectoderm (TE) (p = 0.002833). Associations between successful implantation and patient age, as well as embryo grade, were statistically significant (p = 3.451 × 10⁵ and 3.511 × 10⁻⁴, respectively).
Conclusions: Ultrasound assessment of endometrial thickness and vascularity helps optimize Day 5 embryo transfer timing and implantation. Overall blastocyst quality strongly influences pregnancy outcomes. The study supports incorporating TE and ICM morphological grading to improve embryo selection criteria.
References
Vander Borght M, Wyns C. Fertility and infertility: Definition and epidemiology. Clin Biochem. 2018;62:2-10. DOI: https://doi.org/10.1016/j.clinbiochem.2018.03.012
Kanwal HI, Shahid M, Bacha R. Sonographic evaluation of various causes of female infertility: A literature review. J Diagnos Medi Sonograph. 2022;38(2):155-9. DOI: https://doi.org/10.1177/87564793211052023
Siristatidis C, Sertedaki E, Vaidakis D, Trivella M, Vogiatzi P, Chrelias C. A clinical review of female infertility: From pathophysiology to current diagnostic approaches and treatment options. Frontiers in Endocrinology. 2020;11:591837.
Medical News Today. Dresden D. What to know about endometrial thickness, (2024, August 2). Available at: https://www.medicalnewstoday.com/ articles/327036. Accessed 01 November 2025.
Harper MJ. 10 The implantation window. Bailliere's Clin Obstetr Gynaecol. 1992;6(2):351-71. DOI: https://doi.org/10.1016/S0950-3552(05)80092-6
Poormoosavi SM, Behmanesh MA, Aryannejad S, Janati S. Fresh embryo transfer in the cleavage and blastocyst stages and pregnancy outcomes: A retrospective cross-sectional study. Int J Reproduct BioMedi. 2023;21(5):425. DOI: https://doi.org/10.18502/ijrm.v21i5.13477
Yurci A, Kamar A, Turktekin N, Ozyurt R. Comparison of immediate versus delayed frozen embryo transfer on reproductive outcome. Clin Experim Obstetr Gynecol. 2021;48(2):263-9. DOI: https://doi.org/10.31083/j.ceog.2021.02.2408
Chen X, Fan Y, Ji H, Zhou L, Wu X, Wei Y, et al. Effect of blastocyst morphology and developmental rate on euploidy and live birth rates in PGT-a cycles: a retrospective cohort study. Reproduct Sci. 2025;32(5):1705-12. DOI: https://doi.org/10.1007/s43032-025-01818-6
Xia M, Zheng J. Comparison of clinical outcomes between the depot gonadotrophin-releasing hormone agonist protocol and gonadotrophin-releasing hormone antagonist protocol in normal ovarian responders. BMC Pregn Childb. 2021;21(1):372. DOI: https://doi.org/10.1186/s12884-021-03849-8
Delisle MF, Villeneuve M, Boulvain M. Measurement of endometrial thickness with transvaginal ultrasonography: is it reproducible?. J Ultras Medi. 1998;17(8):481-4. DOI: https://doi.org/10.7863/jum.1998.17.8.481
El-Toukhy T, Coomarasamy A, Khairy M, Sunkara K, Seed P, Khalaf Y, et al. The relationship between endometrial thickness and outcome of medicated frozen embryo replacement cycles. Fertil Steril. 2008;89(4):832-9. DOI: https://doi.org/10.1016/j.fertnstert.2007.04.031
Tomic V, Kasum M, Vucic K. Impact of embryo quality and endometrial thickness on implantation in natural cycle IVF. Arch Gynecol Obstetr. 2020;301(5):1325-30. DOI: https://doi.org/10.1007/s00404-020-05507-4
Lv H, Li X, Du J, Ling X, Diao F, Lu Q, et al. Effect of endometrial thickness and embryo quality on live-birth rate of fresh IVF/ICSI cycles: a retrospective cohort study. Reproduct Biol Endocrinol. 2020;18(1):89. DOI: https://doi.org/10.1186/s12958-020-00636-6
Haas J, Smith R, Zilberberg E, Nayot D, Meriano J, Barzilay E, et al. Endometrial compaction (decreased thickness) in response to progesterone results in optimal pregnancy outcome in frozen-thawed embryo transfers. Fertil Steril. 2019;112(3):503-9. DOI: https://doi.org/10.1016/j.fertnstert.2019.05.001
Weissman A, Gotlieb L, Casper RF. The detrimental effect of increased endometrial thickness on implantation and pregnancy rates and outcome in an in vitro fertilization program. Fertil Steril. 1999;71(1):147-9. DOI: https://doi.org/10.1016/S0015-0282(98)00413-0
Kovacs P, Matyas SZ, Boda K, Kaali SG. The effect of endometrial thickness on IVF/ICSI outcome. Human Reproduct. 2003;18(11):2337-41. DOI: https://doi.org/10.1093/humrep/deg461
Fishel S, Campbell A, Foad F, Davies L, Best L, Davis N, et al. Evolution of embryo selection for IVF from subjective morphology assessment to objective time-lapse algorithms improves chance of live birth. Reproduct Biomed Online. 2020;40(1):61-70. DOI: https://doi.org/10.1016/j.rbmo.2019.10.005
Ng EH, Chan CC, Tang OS, Yeung WS, Ho PC. The role of endometrial and subendometrial vascularity measured by three-dimensional power Doppler ultrasound in the prediction of pregnancy during frozen–thawed embryo transfer cycles. Human Reproduct. 2006;21(6):1612-7. DOI: https://doi.org/10.1093/humrep/dei502
Oborna I, Novotny R, Brezinova J, Petrova P, Lichnovsky V, Fingerova H. Changes in the development of uterine pinopodes in steroid hormone supplemented cycles. Physiol Res. 2004;53:423-30. DOI: https://doi.org/10.33549/physiolres.930500
Nikas G, Psychoyos A. Uterine pinopodes in peri-implantation human endometrium. Clinical relevance. Ann New York Acad Sci. 1997;816:129-42. DOI: https://doi.org/10.1111/j.1749-6632.1997.tb52136.x
Downloads
Published
How to Cite
Issue
Section
