A 16 year old female can become pregnant if she has her period. Under normal circumstances, the general time for girls to have menstruation is 12-14 years old, so 16 years old has already had menstruation, due to the function of the ovaries has returned to normal, there are eggs discharged, there is sexual intercourse will lead to the occurrence of pregnancy in women. So 16-year-old girls must not have sex, because the entire female reproductive organs are not yet mature, including the female vulva, vagina, and the cervix, premature sex will cause damage to the organs, serious cervical cancer, because the occurrence of cervical cancer and premature sex has a very big relationship.