HCG is not progesterone. After pregnancy, the body secretes a special hormone called chorionic gonadotropin, or HCG for short, which doubles as the number of days since menopause increases, and the level of HCG represents the activity of the embryo. However, the final determination of whether the pregnancy is intrauterine and whether the embryo is developing in accordance with the number of days since menopause depends on an ultrasound examination by the obstetrics and gynecology department. Generally, the ultrasound can monitor the gestational sac around 35 days after menopause, the fetal buds can be seen around 42 days after menopause, and the fluctuating fetal heartbeat can be seen around 49 days after menopause, when the intrauterine pregnancy is truly viable. And progesterone is a hormone secreted by the corpus luteum or placenta of pregnancy, which has a supportive and protective effect on the early development of the embryo. Some patients with preeclampsia are caused by low progesterone, so progesterone supplementation is very important in the treatment of preeclampsia.