Significance of increased endometrial thickness in assisted reproduction technology treatments

Purpose: The purpose of this study was to evaluate the relationship between thick endometrium and both implantation and pregnancy rates in ART treatments. Methods: The study group was composed of consecutive women undergoing ultrasonographic evaluation on the day of hCG administration in our ART unit. Endometrial thickness was measured at the thickest part of the midsagittal plane. On the basis of the findings, patients were divided into two groups: A - endometrial thickness >14 mm (above the 95th percentile) and B - endometrial thickness 7-14 mm (between the 5th and 95th percentiles). Patients with a thickness of less than 7 mm were excluded from the study. Results: In all, 1218 cycles were included in the study (50 in Group A and 1168 in Group B). There was no significant difference between the groups in mean patient or mean number of embryos transferred. Similar pregnancy and implantation rates were noted in Group A (24 and 11.3%, respectively) and Group B (27.7 and 14.7%, respectively). Endometrial thickness was found to have a significant positive correlation with the duration of follicular stimulation, and an inverse correlation with woman's age. Conclusions: Increased endometrial thickness (>14 mm) is not associated with decreased implantation or pregnancy rates in assisted reproduction.