Does the ultrasound appearance of the endometrium during treatment with assisted reproductive technologies influence pregnancy outcomes?

We evaluated endometrial pattern, defined as the relative echogenicity of the endometrium on a longitudinal uterine ultrasonic section, as a surrogate for endometrial receptivity in an attempt to evaluate the association between endometrial pattern and pregnancy outcome in women who underwent ART treatment. The primary outcome was live birth and secondary outcomes were clinical intrauterine pregnancy and miscarriage. Potential associations were evaluated using cluster-weighted generalized estimating equations to account for within-couple correlation among repeated ART cycles while adjusting for potentially confounding variables. There were 1034 ART cycles with embryo transfer (778 fresh, 256 frozen) among 695 women (median age: 31.0 (6.0) years). The average number of embryos transferred per cycle was 2.1. The clinical intrauterine pregnancy rate per transfer was 56.0% for fresh and 54.3% for frozen cycles. The overall live birth rate per embryo transfer was 48.4%. Live birth rates were unchanged when the endometrium was semi-trilinear (RR:0.91 CI:0.74,1.12) or unilinear (RR:1.15 CI:0.89,1.49) in comparison to trilinear endometrium after controlling for potentially confounding variables. Results were similar when analysed separately for fresh and frozen cycles and when evaluating associations with clinical intrauterine pregnancy and miscarriage rates. It appears that endometrial pattern does not significantly affect live birth in ART and our data do not support cancelling an ART cycle if the endometrium is less than trilinear.