Publication:

The impact of embryo quality and endometrial thickness on frozen embryo transfer cycles

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.