14-18. Can be younger than 14. You can get a girl pregnant at age 13/14 and into older age. I advise you to wait until you are at least at the age of consent to have sex (16) Use protection and make sure the girl is protected also. Wait until you are old enough, have a job and a house to have kids. Girls can get pregnant once they start their period. Girls can start their period from age 8-16.