The effect of endometrial thickness on IVF/ICSI outcome

Background: During the menstrual cycle the endometrium undergoes cyclic proliferative and secretory changes in preparation for implantation. If this preparation is not sufficient, then implantation will fail. The impact of endometrial thickness on the day of embryo transfer on IVF outcome was investigated in the present study. Methods: A retrospective analysis was conducted of 1228 IVF/ICSI cycles. Stimulation was with clomiphene citrate (CC) + hMG in one-third of the cycles, and ultrashort GnRH agonist stimulation in two-thirds. Cycle parameters were compared between pregnant and non-pregnant patients. A similar comparison was made between ongoing pregnancies and those that resulted in a loss. Results: There were more follicles, oocytes and embryos, the endometrium was thicker and the embryo quality was higher among women who became pregnant when compared with non-pregnant women after assisted reproduction. The pregnancy rate improved as endometrial thickness increased. No difference in cycle parameters and endometrial thickness was found between ongoing pregnancies and pregnancies that resulted in a first-trimester loss. CC had no measurable adverse endometrial effect, but the pregnancy rate was lower in CC+hMG cycles. Conclusions: Increased endometrial thickness is associated with higher pregnancy rates. However, neither attainment of pregnancy nor pregnancy outcome was predicted by endometrial thickness alone.