| Yes, it is. Unlike the old riddle, "What comes first, the chicken or the egg?" we know for sure that the egg comes before menstruation. If there is no pregnancy after the egg is released from the ovary, the lining of the uterus breaks down and a woman has her period. This is also the way her first period starts.
It is very important for a young woman to know that vaginal intercourse before her first period can cause pregnancy. If she decides to have intercourse before her first period, she must be sure to use contraception to avoid an unintended pregnancy. | 
