If you are sure that you are having a period, it means that you are not pregnant. If you have only a small amount of bleeding, it is not necessarily a period, but may be a reaction to the early stages of pregnancy. If you have a period close to the time of your period, and the amount of bleeding is the same as before, it means you are not pregnant. If there is only a small amount of bleeding near the time of the period, it is possible that it is not the onset of menstruation because, if conception occurs, some women may also experience a small amount of vaginal bleeding due to fluctuating hormone levels in the body and stimulation of the uterine lining when the fertilized egg is deposited. In addition to this, women who have miscarriages or pre-miscarriages after pregnancy and extra-uterine pregnancies will experience vaginal bleeding, causing some women to mistake it for menstruation. Therefore, if the amount of menstruation is abnormal, or the menstrual cycle is more variable than before, it is important to consult a doctor in time to rule out other causes of vaginal bleeding, so as to avoid delaying the condition.