Vaginal flow in the third trimester is likely to be caused by premature rupture of the amniotic membrane, which may be caused by the usual vaginitis and cervicitis of the pregnant woman and the retrograde infection of inflammation leading to premature rupture of the fetal membrane. Fetal preservation treatment should be carried out. Gynecological ultrasound examination should also be done to check the development of the fetus, and progesterone, or dydrogesterone should be taken for fetal preservation treatment under the guidance of the doctor according to the examination results. As the month of pregnancy increases, the secretion of estrogen in the body gradually increases, causing an increase in vaginal discharge. Therefore, during pregnancy, you should change and wash your underwear regularly and wash your vulva with warm water. If you have yellowish leucorrhea, odor and vulvar itching, you should cooperate with your doctor to have a leucorrhea test to confirm whether you have bacterial or mycobacterial vaginitis, and then use medication to treat the symptoms under your doctor’s guidance.