You can have intercourse when your period is about to come.
The fact that you are about to have your period means that you are not yet having your period, that is, the lining of the uterus has not yet fallen off, and you can have sex at this time. Sexual intercourse is prohibited during menstruation because it can cause infections in the reproductive organs. As long as there is no vaginal bleeding and no bloody discharge, you can have sex, and it will not affect your genitals.
If a small amount of bleeding is found, it means that the uterine lining has begun to shed, and intercourse at this time may cause retrograde infection of pathogenic bacteria, which may lead to inflammation of the reproductive tract, so it is necessary to strictly control the time of coitus.
Regardless of the time of coitus, it is necessary to maintain local hygiene, strengthen vulvar care, and reduce the production of inflammation.