Association between Myometrial Thickness and Assisted Reproductive Technologies Outcomes: A Prospective Cohort Study

Background: Myometrial thickness has been expected to be a prognosticator for lower uterine segment function. Anabnormal function of the uterine muscle layer can cause common and important reproductive problems. This studyaimed to evaluate the relationship between the baseline myometrial thickness and assisted reproductive technologies(ART) outcomes. Materials and Methods: In this prospective cohort study, 453 infertile women undergoing ART cycles without anyobvious uterine pathology, participated in this prospective cohort study from February 2013 to May 2015. In order tomeasure the myometrial thickness in the anterior and posterior of the uterine, trans-vaginal ultrasounds were conducted ondays 2-4 of the cycle (menstrual phase) preceding ovarian stimulation and the day of human chorionic gonadotropin (hCG) injection. We defined three groups based on the baseline myometrial thickness in the anterior and posterior, including(A) 25 mm, (B) 25-29.9 mm and (C) ≥30 mm. Ovarian stimulation, oocyte retrieval and luteal phase support wereperformed in accordance with the standard long protocol. Two weeks after embryo transfer, the patients underwent apregnancy test by checking their serum β-hCG levels. The primary outcome measure was the clinical pregnancy rate. Secondaryoutcome measures were implantation rate, abortion rate and live birth rate. Results: The clinical pregnancy (P=0.013) and implantation (P=0.003) rates were significantly lower in group A than in two other groups. Although the live birth rate was lower in group A than two other groups, this decrease was not statisticallysignificant (P=0.058). Conclusion: The findings may be a way for clinicians to draw focus on providing therapeutic strategies and a specificsupportive care for women with a baseline myometrial thickness 25 mm in order to improve the reproductive outcomeof in vitro fertilization/intracytoplasmic sperm injection (IVF-ICSI).