1. Women have menstrual cramps, endometrial bleeding, some endometrial rupture and shedding, and some blood vessels are also exposed. At this time, sexual intercourse, after being stimulated locally, will increase menstrual flow, or will prolong menstrual days and aggravate menstrual discomfort.

2. Sexual intercourse at this time is easy to cause bacterial infection. Moreover, the uterine orifice is also slightly stretched. Moreover, due to the discharge of menstrual blood, the acidic environment in the vagina is diluted, and the self-cleaning ability of the vagina is weakened. At this time, during sexual intercourse, the male genitals will bring bacteria, infect the endometrium and cause pelvic inflammation, which will bring pain to the woman. Some women will have a resurgence a few days after menstruation. In this case, we should pay more attention to avoid sexual intercourse pollution. In addition, we should also pay attention to the fact that even if condoms are used during menstrual period, Because condoms can only prevent sperm from entering the vagina, but they can't prevent bacteria from being brought into the vagina, it is also harmful.

3. During menstrual sexual intercourse, women's menstrual secretions enter men's urethra, which will cause urethral irritation in men.

4. Sleeping in the same room during menstrual period may lead to infertility. Because sperm meet with spilled blood cells at the damaged part of endometrium and even enter the blood, it may lead to immune cell allergy in the middle period. It also stimulates the body to produce anti-sperm antibodies, which can exist in female cervical mucus and serum. Once sperm antibodies come into contact with sperm again, it will stimulate the body's immune rejection, thus affecting the combination of sperm and eggs and leading to infertility.