Maggie's training regimen may put her at risk to develop secondary amenorrhea. While amenorrhea is the absence of menstruation, secondary amenorrhea is the absence of the menstrual cycle in females who have started menstruating (having had at least one cycle) and then stop menstruating for a period longer than three months. Secondary amenorrhea occurs in times of extreme stress or weight loss (such as anorexia). Female soldiers have experienced secondary amenorrhea when they have gone to war or have become prisoners of war. Hormone shots, extreme weight gain, birth control, and certain medications also cause the condition.