If you have intercourse without measures during ovulation, which can cause pregnancy, your period can be delayed indefinitely. 12 days after intercourse, you can buy an early pregnancy test to exclude yourself from conception and to avoid delaying your period due to emotional factors. In case of delayed menstruation without pregnancy, as long as it is delayed within 7-10 days, it is considered a normal cycle, sometimes the environment, stress, mental factors can also cause delayed menstruation, once in a while will not affect health and reproductive health, so do not worry too much. In the future, if you need to prepare for pregnancy, you should have intercourse during ovulation, and if you need contraception, you should use condoms as much as possible during any period of time to avoid changes in ovulation due to environmental changes and stress.