There is no authoritative information on how old is suitable for girls to have sex, and it is suggested that girls can have sex after the age of 18 to 20. In addition, women should avoid having sex too early. Generally speaking, women will have menstruation at the age of 11~16 years old, and after menstruation, their genitals will gradually develop and mature, and most of them will have sexual maturity at the age of 18~20 years old, at this time, not only do women’s ovaries begin to ovulate regularly, but also their genitals are mature, so women can have sex at this time. Women should not have sex before the age of 18 because the reproductive organs are not yet fully developed, and having sex too early will increase the risk of cervical cancer, as well as increase the chances of vaginitis, cervicitis and other gynecological diseases. It is generally recommended that women have sex after the age of 18 to 20, and the first time they have sex, they need to clean their genitals to prevent infection. In addition, for women who do not intend to get pregnant, they can do a good job of contraception during sex.