If you have intercourse on the first day of menstruation, it is recommended to do the following: First, intercourse during menstruation may lead to pathogenic bacteria invasion and cause inflammatory reactions in the reproductive tract, so this time, in addition to keeping the vulva clean and changing sanitary napkins regularly, it is also recommended to take oral antibiotics for two days, mainly to prevent pathogenic bacteria infection, so as not to cause endometritis, cervicitis or pelvic inflammatory disease. Secondly, intercourse on the first day of menstruation may lead to contraction of the smooth muscle of the uterus through sexual stimulation, which will close the inner cervical opening and cause menstrual blood in the uterine cavity to enter the pelvic cavity, thus easily leading to endometriosis, you can drink hot brown sugar and ginger water, which has the effect of expelling cold and warming the uterus, and can make the menstrual blood flow more smoothly and minimize the possibility of endometriosis caused by menstrual blood reflux. The possibility of endometriosis caused by menstrual blood reflux is minimized.