Women are not allowed to have sex during their first period, and they will not be able to conceive because ovulation occurs 14 days before the next period. It is important to note that women are not allowed to have sex during menstruation because sex during menstruation can cause infection to the reproductive system. The resistance of women’s reproductive system is weak during menstruation, and sex will bring pathogenic microorganisms into the female reproductive system, which will easily cause infection in women, and in serious cases, may even lead to women not being able to get pregnant and have children normally, and may also cause endometriosis, which is caused by sex during menstruation, resulting in the shedding of endometrium being squeezed into the myometrium This can cause endometriosis in the myometrium, resulting in menstrual disorders, dysmenorrhea and even infertility, so it is absolutely forbidden for women to have sex during menstruation, and they will not get pregnant at this time.