Does it affect the live birth rates to have a maximum endometrial thickness of 7, 8, or 9 mm in in-vitro fertilization-embryo transfer cycles?

Abstract

Objective To assess the effect of endometrial thickness (EMT) on live birth rates (LBR) in women with endometrial lining between 7.0–9.9 mm. Methods This retrospective cohort study included women who underwent fresh and frozen embryo transfers between 2008 and 2018, grouped according to their maximum EMT; group 1, 7.0–7.9 mm; group 2, 8.0–8.9 mm; and group 3, 9.0–9.9 mm and underwent blastocyst transfer. Results The study included 7,091 in-vitro fertilization cycles: 1,385 in group 1, 3,000 in group 2, and 2,706 in group 3. The combined LBR was 22.2%. The mean age of women at oocyte retrieval day was 36.7±4.5 years. There was no difference in female age at oocyte retrieval or in the quality of embryos transferred between the three groups. Group 1 had more diagnoses of diminished ovarian reserve (25.8% vs. 19.5% and 19.1%; P<0.001) and less male factor infertility compared with group 2 and 3, respectively (25.0% vs. 28.8% and 28.5%; P=0.024). LBR was higher with increasing endometrial thickness, group 2 vs. group 1 (22.0% vs. 17.4%; P=0.0004), group 3 vs. group 1 (25.0% vs. 17.2%; P<0.001), and group 3 vs. group 2 (25.0% vs. 22.0%; P=0.008). After controlling for confounding factors, these three groups did not differ in LBR (group 1 vs. group 2, odds ratio [OR], 1.08; 95% confidence interval [CI], 0.83–1.4; P=0.54 and group 1 vs. group 3, OR, 1.16; 95% CI, 0.90–1.51; P=0.24). Conclusion Live birth rates in women with endometrial thickness between 7.0–9.9 mm were not affected by different cut-offs when blastocyst transfer was performed.

Keywords

• endometrium thicknes
• live birth
• embryo transfer