Impact of HCG level after Frozen Embryo Transfer (FET) on Ongoing Pregnancy Rate

14 days after embryo transfer, an HCG value of 500 mIU/mL or higher is a good indicator that the pregnancy will progress to the point where a fetal heart beat will be detected on transvaginal ultrasound. Sometimes with HCG values as low as 100 mIU/mL the pregnancy will still progress normally.

The corpus luteum seems to play an important role in luteal phase support because for a given hCG value there is a higher chance of seeing a fetal heartbeat on transvaginal ultrasound (usually evaluated at 6 weeks 5 days at our center) if the embryo transfer occurred after an ovulation (“Ovulatory FET” in the graph below).