Half a month early menstruation is not necessarily pregnancy, the causes of half a month early menstruation are as follows: 1, ovulation bleeding, which is a physiological phenomenon, usually does not require treatment, bleeding is small and does not last long. 2, the last cycle of menstruation did not come or have menstruation, but the amount of menstruation is very small, this time menstruation is 15 days earlier than expected, and there is sexual intercourse, consider the possibility of pre-eclampsia abortion, clinical manifestations are Vaginal bleeding and abdominal pain, which, if not treated in time, may lead to inevitable miscarriage. 3. Cervical disease, mostly vaginal bleeding after intercourse, with small amount and red color. Active bleeding from the cervix is seen in gynecology. Abnormal vaginal bleeding needs to be seen in hospital in time for clear diagnosis and then symptomatic treatment.