The pain around the perineum in the eighth month of pregnancy may be caused by the enlargement of the uterus, the descent of the fetus into the pelvis, or vaginal inflammation, etc. You should rest in the side-lying position, keep the local area clean and hygienic and use medication under the guidance of a professional doctor. 1. Uterine enlargement: If the uterus enlarges and presses the inferior vena cava during the eighth month of pregnancy, resulting in the obstruction of venous blood return, it may cause pain in the perineum and lower limbs. Usually, you should avoid sitting and standing for a long time, and take proper activities, and take a rest in side-lying position, which can alleviate the pain around the perineum. 2. Fetal descent into the pelvis: If the fetus descended into the pelvis in the eighth month of pregnancy and pressed the pelvis, it will also cause pain around the perineum, which will disappear after the delivery of the fetus, and does not require special treatment. Usually, you should rest in the side-lying position and avoid prolonged standing and sitting. 3. Vaginal inflammation: If vaginal inflammation occurs during the eighth month of pregnancy, accompanied by perineal pain, vulvar itching, leukorrhea and other symptoms, you should cooperate with a professional doctor to conduct a vaginal secretion test to clarify the type of inflammation, and then give vaginal medication, including metronidazole suppositories, nifurtimox tablets, etc., but the medication needs to be under the guidance of a professional doctor, avoid self-medication. If you feel pain around the perineum in the eighth month of pregnancy, it is recommended that you go to a regular hospital as soon as possible for consultation and treatment, and be sure to use the medication in strict accordance with the doctor’s instructions.