The Outcome of Repeated In Vitro Fertilization-Embryo Transfer Based on the Endometrial Thickness

Objective: To determine whether in vitro fertilization embryo transfer (IVF-ET) outcome is affect- ed by endometrial thickness. Design: Retrospective study. Setting: IVF-ET unit in Osaka Medical College. Patients: Twenty-eight patients with tubal infertility who became pregnant following IVF-ET between 1998-2000. All patients underwent 2 cycles of IVF-ET with long down-regulation protocol of Gonadotorophin releasing hormone analogue (GnRHa) and became pregnant following one of them. These fifty-six courses were divided into pregnant and non-pregnant courses. Main Outcome Measure(s): Endometrial thickness, serum E2 and LH levels, number of oocytes, fertilization rate, cleavage rate, high quality embryo rate and pregnancy rate were investigated. Results: The endometrium in the pregnant courses were thicker than those in the non-pregnant courses (P<0.05). Serum E2 level showed direct correlation with endometrial thickness (R=0.882, P < 0.001). The courses with endometrial thickness greater than or equal to 10 mm showed a signifi- cantly higher pregnancy rate than courses with endometrium of less than 10 mm. Although there was no statistical difference in high-quality embryo rate or number of transferred embryo rate between the two groups, the fertilization rate of the courses with endometrium greater than or equal to 10 mm was higher than that in the courses with endometrium less than 10 mm. Conclusion: Although the number of transferred embryos and embryo quality does not affect the pregnancy rate, endometrial thickness might play an important role in the success of IVF-ET.