The 1st ultrasound is usually done 4 weeks after the transfer. The ultrasound at this time is mainly to see if the pregnancy is intrauterine and extrauterine, because there are many IVF cases where the embryos are transferred in the uterine cavity, but there are still cases where the embryos end up planted in the fallopian tubes. And there are embryos that develop quickly and it is also possible to see if there is a fetal heart and if there is no fetal heart, the patient will be instructed to wait another 1 week and then recheck to see if there is a fetal heart. So don’t stop the medication for luteal support after the transplantation and don’t stop it too early. After the 1st ultrasound, if there is no fetal heart, you have to wait for the 2nd ultrasound to see the fetal heart before reducing the dosage, and you should not stop all of it, but stop the medication gradually. After the 1st ultrasound to determine that it is intrauterine, do not worry if there is no fetal heart, because you can still wait for 1 week and then some patients have a fetal heart.