Abstract

Background: Endometrial thickness is regarded as an indicator of the receptivity of the endometrium. Patients preparing for frozen embryo transfer need some interventions in case their endometrium is thin. Objective: This study aimed to compare the clinical outcomes of oral administration of estradiol valerate with its vaginal type in women with inappropriate endometrial thickness. Materials and Methods: This cross sectional study comprised of 79 women (cycles) who had undergone frozen-thawed embryo transfer. On the 13th day of the cycle, vaginal sonography was performed in case the thickness of the endometrium was < 7 mm; in the oral group, the patients continued using oral estradiol valerate tablet. However, in the vaginal group, the participants applied estradiol valerate tablet vaginally. Finally, the chemical and clinical pregnancy rate, also, early miscarriage rate were compared between the two groups. Results: The early miscarriage rate was lower in the vaginal group in comparison with the oral group (p = 0.040). Women in the vaginal group showed a lower rate of chemical pregnancy compared to the oral group, but this difference was not statistically significant (25.0 vs. 34.4, p = 0.440). The rate of clinical pregnancy in the two groups was not statistically significant, although the vaginal group had a higher pregnancy rate (22.5 vs. 15.6, p = 0.464), especially in women older than 34 years (37.5 vs. 11.1, p = 0.355). Conclusion: Vaginal administration of estradiol tablet in women with thin endometrium leads to a lower rate of early miscarriage.