HCG is normal, but progesterone is low. If there is no other discomfort, and if the frequency of follow-up checks is increased, and progesterone does not continue to fall, and can be maintained at a more normal level, there is no need to worry excessively. Progesterone can fluctuate with the increase of gestational weeks and is an important hormone to maintain pregnancy, but it is not the only evaluation indicator. It is necessary to pay attention to exclude that the pregnant woman has insufficient luteal function or has underlying diseases of the endocrine system that affect the regulation and secretion of hormones by the gonadal axis, such as hypothyroidism, insulin resistance, abnormal adrenal function and other diseases. If the symptoms of abdominal pain and vaginal bleeding are also present, the presence of preterm abortion should be suspected, and progesterone and human chorionic gonadotropin should be monitored dynamically to keep an eye on the fetus in utero.