A woman who has intercourse and has a normal period will not get pregnant. However, vaginal bleeding after intercourse when a woman reaches her period is not necessarily a real period, but may be in the following three special cases. In these three special cases, the patient is bleeding due to pregnancy and not a real period: First, the patient has a biochemical pregnancy, so there is bleeding. Patients with biochemical pregnancy have vaginal bleeding like menstrual bleeding mostly clears on time and after the end of regular blood or urine HCG checks can gradually drop to normal or become (-). Secondly, the patient has abnormal bleeding due to intrauterine pregnancy, preterm miscarriage or ectopic pregnancy. The diagnosis can be clarified by dynamic observation of the changes in HCG, progesterone and ultrasound. The patient’s needs and the results of the examination will be used to treat the symptoms. Third, the patient should be considered to have cyclic vaginal bleeding after pregnancy. This condition is called menstrual stimulation from the Chinese medicine perspective. This type of vaginal bleeding does not affect the development of the embryo and usually does not require special treatment.