Endometrial thickness as a predictor of pregnancy outcomes in 10787 fresh IVF–ICSI cycles

Abstract This retrospective study assessed the predictive value of endometrial thickness (EMT) on HCG administration day for the clinical outcome of fresh IVF and intracytoplasmic sperm injection (ICSI) cycles. A total of 8690 consecutive women undergoing 10,787 cycles over a 5-year period were included. The 5th, 50th and 95th centiles for EMT were determined as 8, 11 and 15 mm, respectively. Group analysis according to these centiles (Group 1: 11 and ≤15 mm; Group 4: >15 mm) demonstrated significant differences ( P < 0.001) in clinical pregnancy rates (23.0%, 37.2%, 46.2% and 53.3%, respectively), live birth rates per clinical pregnancy (63.3%, 72.0%, 78.1% and 80.3%, respectively), spontaneous abortion rates (26.7%, 23.8%, 19.9% and 17.5%, respectively), and ectopic pregnancy rates (10.0%, 4.3%, 2.1% and 2.2%, respectively). Logistic regression analyses showed EMT as one of the independent variables predictive of clinical pregnancy (OR = 1.097; P < 0.001), live birth (OR = 1.078; P < 0.001), spontaneous abortion (OR = 0.948; P < 0.001), and ectopic pregnancy (OR = 0.851; P < 0.001). Future research should aim to understand the underlying mechanisms relating EMT to conception, ectopic implantation and spontaneous abortion.