Mid-pregnancy although the fetus is more stable, coitus with brown discharge may generally be more serious, may be the first sign of miscarriage, cervical polyps, vaginitis and other diseases lead to. 1. Pre-eclampsia: It is caused by embryonic factors, maternal factors, paternal factors and environmental factors. A small amount of vaginal bleeding before the 28th week of pregnancy will lead to the appearance of brown discharge, which can seriously lead to miscarriage. 2. Cervical polyp: It is a limited hyperplasia of the glands and mesenchyme of the cervical canal caused by chronic inflammatory reaction and cervical infection, which will lead to abnormal vaginal bleeding or brown sticky vaginal discharge, and need to be surgically removed for treatment. 3. Vaginitis: It is an inflammation of the vagina caused by bacterial infection, fungal infection, trichomonas infection, etc. It is mainly manifested by abnormal vaginal discharge such as brown discharge, itching, pain, burning sensation and other symptoms in the vagina, which need to be treated with medication. Mid-pregnancy coitus with brown discharge may also be seen in placental abruption, placental hypoplasia and other diseases, if the symptoms of mid-pregnancy coitus with brown discharge, persistent and unrelieved, you need to consult a doctor in time for treatment.