What causes amenorrhea?

Secondary amenorrhea usually indicates pregnancy, as the uterine lining remains to provide nutrition to the fertilized egg. Secondary amenorrhea can also be caused by the following situations:

• Contraceptives, including oral medication, injections, or those containing progesterone, can disrupt the menstrual cycle for up to six months after use.
• Hormonal disorders, such as polycystic ovary syndrome. This disorder is indicated by an imbalance of estrogen and the male hormone androgen, and can cause facial hair, amenorrhea or overly heavy menstruation, and obesity.
• Uterine scarring (otherwise known as Asherman's syndrome) from surgery.
• Premature menopause (also known as primary ovarian insufficiency), in which a woman's supply of eggs diminishes before age 40.
• Eating disorders, such as anorexia or bulimia, cause abnormally low body weight and disrupt the body's balance of hormones.
• Other drugs, such as antidepressants, chemotherapy, hallucinogenic drugs, or cocaine.