Amenorrhea is a condition in which a woman does not menstruate or experiences one or more missed menstrual periods. There are two types of amenorrhea: primary amenorrhea and secondary amenorrhea. Primary amenorrhea is when a girl does not get her period by age 15. Secondary amenorrhea is when a female has had a normal menstrual cycle, but stops getting them or has missed at least three consecutive menstrual periods. Less than one percent of girls in the United States have primary amenorrhea.