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

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.

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.

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.

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.