A suboptimal endometrial pattern is associated with a reduced likelihood of pregnancy after a day 5 embryo transfer.

This retrospective study examined the association of endometrial pattern and pregnancy after a day 5 ET. The pregnancy rate of women with a triple-line ultrasound endometrial pattern on the day of hCG administration was significantly higher than the pregnancy rate of women with the other ultrasound patterns. This observation suggests that, in a subset of patients, a suboptimal endometrial lining may interfere with assisted reproductive technology success.