Bleeding is likely to occur after pregnancy, but depending on the number of weeks of pregnancy, the causes of bleeding are different in early pregnancy than in mid to late pregnancy. If you experience a small amount of vaginal bleeding, blood in the vaginal discharge, brownish discharge, or a small amount of fresh blood, or no heavy menstrual flow in early pregnancy, you should be aware that it may be a sign of preterm abortion. The first thing you should do is to rest in bed and try to rest and not to do any physical work. If you have back pain and stomach pain, you may need to take fetus preservation medication, such as Chinese herbal medicine, and also go to the hospital to take blood for ultrasound to see if the development of the fetal sac and embryo is normal. Blood will be collected to measure the progesterone to see if the preterm miscarriage is caused by insufficient luteal function. If the progesterone level is low, you may need to take progesterone and progesterone pills to supplement the progesterone function. If the bleeding occurs in the mid to late stages, it may be more related to the placenta. Low placenta, placenta praevia or placenta abruptio may cause bleeding in the mid to late stage. This bleeding is usually painless and also needs to be detected by ultrasound at the hospital.