Swimming is prohibited during menstruation because during menstruation, the endometrium is shed from the cervical os and the cervical os is open. If you swim, including taking a bath in the tub, it may cause retrograde infection and endometritis and tubitis in the uterus. In severe cases, it may also cause abdominal pain, or even continuous bleeding and high fever, so swimming during menstruation is prohibited. It is also important to keep warm during menstruation because the resistance is weak and weak. If you do not pay attention to hygiene, including not keeping warm, it can easily cause symptoms of cold. You should also pay attention to menstrual hygiene and wash your vulva every day to avoid itching and even vaginitis during menstruation.