Objective: To determine whether there is a maximal value for endometrial thickness, as measured on the day of hCG administration, above which implantation and pregnancy are unlikely to occur. Design: Retrospective analysis. Setting: A university-based tertiary care center for assisted reproductive technology. Patient(s): A total of 809 IVF cycles in 623 patients resulting in ET. Intervention(s): Endometrial thickness was measured by means of transvaginal ultrasound on the day of hCG administration. Cycles were divided into two groups based on endometrial thickness. Group A consisted of 680 cycles with 'normal' endometrial thickness (7-14 mm), and group B included 37 cycles with 'increased endometrial thickness' (>14 mm). Main Outcome Measure(s): Implantation, clinical pregnancy and miscarriage rates. Result(s): Group B cycles had significantly lower implantation and pregnancy rates compared with group A (3% versus 15% and 8.1% versus 29.7%, respectively). Two of 3 pregnancies (66.6%) from group B miscarried, compared with 44 of 202 (21.8%) pregnancies in group A. Conclusion(s): Patients with endometrial thickness of >14 mm on the day of hCG administration comprise approximately 5% of the patients who undergo ET in our program. Our experience suggests that implantation and pregnancy rates are significantly reduced, and miscarriage rates may be increased in this group.
Weissman, A., Gotlieb, L., & Casper, R. F. (1999). The detrimental effect of increased endometrial thickness on implantation and pregnancy rates and outcome in an in vitro fertilization program. Fertility and Sterility, 71(1), 147–149. https://doi.org/10.1016/S0015-0282(98)00413-0