The main criterion for pregnancy on the 12th day of transfer is the level of chorionic gonadotropin in the blood, which rises to 100 units per liter to be considered a successful pregnancy. When the embryo is successfully transferred, it will reach the bed in about 6-7 days. After the embryo reaches the bed, it secretes chorionic gonadotropin, which doubles in the early stages of pregnancy, and in the case of the better-grown embryos, it doubles every other day, so that the hormone level can be determined after 10 days of transfer. The 12 days after the transfer is still an early period, the specific differences are also relatively large, mainly based on the development of the embryo to determine whether the pregnancy, it is recommended that the patient can carry out a blood test to determine the level of human chorionic gonadotropin in the body, or check every other day to determine whether there is a doubling of the situation. If the chorionic gonadotropin level doubles every other day, it is considered that the embryo is developing well, and if it does not double or continues to get lower, it is recommended that the patient consult the obstetrics and gynecology department of a regular hospital to rule out the existence of preterm miscarriage.