There are open wounds in the uterus and menstrual blood is a good culture medium, making it easy for pathogenic bacteria to invade the uterus, fallopian tubes, ovaries, and pelvis and induce infection symptoms. Most of the ovulation days for those who usually have regular menstrual cycles are on the fourteenth day before the next menstrual period, with the first five and last four days being the ovulation period. Some people may experience a small amount of vaginal bleeding and discomfort in the lower back and abdomen, which need to be distinguished from normal menstrual flow. If you are not planning to have a baby in a short period of time, you should take effective contraceptive measures, such as using condoms during intercourse or taking short-acting contraceptive drugs regularly.