A small amount of dark blood in the early stages of pregnancy may be caused by exertion or coitus stimulation, which is the precursor of miscarriage; it may also be caused by low progesterone or low HCG, so in this case, go to the hospital in time for examination. Ultrasound should be performed to find out the condition of the gestational sac, the implantation condition and whether there is any accumulation of blood in the gestational sac; progesterone test, estrogen test and blood β-HCG test, and even thyroid function test; or liver and renal function test and cysteine test, to find out whether there is any easy embolism and so on, and then according to the results of the test, the patient should be given symptomatic treatment of fetal preservation. The patient should absolutely forbid sexual intercourse, can’t be active, give progesterone or low molecular heparin calcium injection to protect the fetus, and should be regularly rechecked.