On average, it first happens when a girl is between 12 and 13. It's important for young women to know that their first ovulation will happen before their first period. This means that a young woman can become pregnant from vaginal intercourse before her first period. When you a pregnant 13-year-old, there are some added risks of pregnancy; your body may not be fully developed yet to carry a child to term and have a safe delivery. A doctor can answer all of your questions and make sure you receive the care you need to keep you safe and healthy. im pregnant guys ,pls not hate. i cant help it