The effect of embryo migration after embryo transfer with fresh oocyte donation cycles on pregnancy outcomes

Embryo migration is defined as the movement of embryos to implant at the exact site in the endometrial cavity during assisted reproductive technology (ART). We aimed to evaluate the impact of embryo migration on clinical pregnancy (CPR) and live birth rates (LBR) in fresh oocyte donation (OD) cycles. A total of 611 fresh OD cycles was recruited in this prospective cohort study. All embryos were expulsed to upper-middle uterus between 10 and 20 mm from the fundus. Air bubble-fundus distance was measured using ultrasound (USG) at the time of embryo transfer (ET) and then 60 minutes after ET. Patients were divided into 3 groups; first group consisted of patients whose embryos migrated towards fundus, second group whose embryos remained between 10 and 20 mm from fundus and the third group including embryos which migrated towards cervix. There was no significant difference between the groups regarding CPR and LBR (<i>p</i> = 0.359 and <i>p</i> = 0.865, respectively). Our study revealed that embryo migration was a fact and almost 22% of embryos migrated towards the fundus or the cervix. On the other hand, whether the embryo stayed static or migrated, CPR and LBR did not differ significantly in fresh OD cycles.