It is possible for a girl to be fertile at age 14. A girl is fertile when she has her period and has regular ovulation. A 14-year-old girl is fertile if she is already menstruating, i.e., if she has regular ovulation. The reproductive organs usually begin to develop when a woman is about 12 years old. 14-year-old girls may be fertile even though they are only children and their reproductive systems are not yet complete. However, if a girl has not had her period at this time, that is, she has not ovulated regularly, that is, she is not fertile. As 14-year-old girls are still relatively young, it is important to ensure adequate nutrition to replenish the body and to provide proper sex education to the child.