Assessment of the relationship between endometrial thickness and number of dominant follicles in pregnancy rate among 361 intrauterine insemination cases

The size of the follicles and endometrial thickness are two important factors in pregnancy rate of patients undergoing intrauterine insemination (IUI). The likelihood of ovulation increases with follicular diameter and the fecundity increases with endometrial thickness. The other important factor in IUI is the number of follicles. In this study, we investigated the role of the endometrial thickness and the number of dominant follicles on pregnancy rate in patients undergoing IUI. The study group was the patients who were undergoing IUI during 6 years period in Amir-al-Momenien Hospital of Semnan. Ovulation induction was launched for all patients and when there was appropriate endometrial thickness (≥6 mm) and at least one dominant follicle (≥16 mm) in trans-vaginal ultrasonography. Thirty six hours after injection of HCG, IUI was performed. After survey of patients file, the number of dominant follicles and endometrial thickness were recorded. Then the pregnancy rate between patients with equal or more than 3 dominant follicles or less than 3 dominant follicles and patients with equal or more than 7mm endometrial thickness with less than 7 mm. we used student t test for statistical analysis. About 361 cases of IUI were performed and pregnancy happened in 70 cases (19.4 %). In non-pregnant group (291 cases), 133 cases had equal or more than 3 dominant follicles and 158 cases had less than 3 dominant follicles. In pregnant group (70 case) 37 cases had equal or more than 3 dominant follicle and 33 cases had less than 3 dominant follicles in the time of HCG injection. Statistical analysis revealed no significant differences in pregnancy rate between two groups (p= 0.317). With regard to endometrial thickness, 222 cases had equal or more than 7 mm endometrial thickness and 69 cases had less the 7 mm in non pregnant group (291 cases). In pregnant group (70 cases) 68 cases had equal or more than 7 mm endometrial thickness and 2 cases(2.8%) had less than 7 mm. Statistical analysis showed a significant difference in pregnancy rate between two groups (P<0.0001). Findings of this study indicated that the pregnancy rate in IUI method has a significant relation with endometrial thickness equal or more than 7 mm, but there is no such relationship with equal or more than 3 dominant follicle