The symptoms and harms of low progesterone vary between women who are pregnant and those who are not, and need to be analyzed specifically. Progesterone can reduce the excitability of uterine smooth muscle and inhibit contractions, which is conducive to the normal growth and development of the embryo in the uterus. A woman who is pregnant and has a low progesterone level may result in the growth and development of the embryo being restricted, which in turn may cause symptoms such as stomach ache, vaginal bleeding, etc., and may lead to fetal underdevelopment, miscarriage with an omen, or even miscarriage. Progesterone has a certain role in adjusting the menstrual cycle. If a woman is not pregnant and has low progesterone, it may cause symptoms such as shortened menstrual cycle and a small amount of vaginal bleeding in the pre-menstrual period, which may affect the woman’s menstruation and fertility and other functions. If the test reveals that progesterone is low, it is recommended to consult the attending physician for further examination and treatment.