A number of risks that will be faced if you have sex during menstruation are:
The dirty blood of menstruation reverses to the uterus, even other organs. This condition will cause the menstrual blood stick to the place where it shouldn't and develop into new tissue. If it happens, endometriosis will cause pain, either during menstruation or sex.
Endometriosis can even develop into cyst that impacts quite seriously, such as difficult to have children. Endometriosis isn't a disease that causes death, but its effect can degrade the quality of life.
An intimate relationship will usually cause injury, and unsterile sperm can enter the body, causing infection. During menstruation, you also experience a decrease in the hormone estrogen, which means that lubrication fluid is being reduced. Therefore, the vaginal organs are vulnerable to injury and cause discomfort during sex.
The best time to have sex is about 14 days after the menstrual cycle. This is because the clitoris will grow about 20 percent and be more sensitive to stimulation, easier to reach orgasm and, of course, riskless.