Ideal embryo transfer position and endometrial thickness in IVF embryo transfer treatment.

Objective: To establish an ideal transfer strategy by investigating the relationships among embryo transfer (ET) depth, endometrial thickness, and subsequent in vitro fertilization treatment clinical pregnancy outcomes.

Methods: In the present retrospective analysis, data from in vitro fertilization-ET treatment cycles conducted at a fertility center in Shanghai, China, between October 2014 and March 2015 were analyzed. Women were divided into groups 1-4 according to transfer depth (<10; 10-15, 15-20, and >20 mm, respectively), as measured by air bubbles. Additionally, 391 women were divided into groups A-C according to endometrial thickness (<7, 1-12, and >12 mm, respectively). Clinical pregnancy outcomes were assessed by group.

Results: Data from 501 cycles were included. Clinical pregnancy and live delivery rates were significantly higher in group 2 (P=0.009 and P=0.002, respectively) and group 3 (P=0.008 and P=0.001, respectively) than in group 4. Among the 394 patients with endometrial thickness data available, clinical pregnancy and live delivery rates were higher in group B (P=0.028 and P=0.015, respectively) and group (P=0.013 and P=0.013, respectively) than in group A.

Conclusion: Correct transfer depth and endometrial thickness can increase the rates of clinical pregnancy, implantation, and live delivery. Placing the embryos at 10-20 mm from the fundus and at an endometrial thickness of more than 7 mm is recommended for optimal clinical pregnancy outcomes.