Is Missing a Period Normal?

Amenorrhea, the lack of menstrual periods, can have a variety of causes. In many cases, the reason for not menstruating is a normal, expected occurrence. In other cases, failure to menstruate signals a problem. By understanding some of the reasons why you might miss a period, you will have a better idea of whether you should see your doctor to discuss your lack of menstruation.

Reproductive Causes

• A number of physiologically normal reasons for missing a period are connected to a woman's reproductive cycle. The number one reason women don't menstruate is pregnancy, according to Drugs.com. After a pregnancy has ended, it takes a period of time for a woman's cycles to return to normal. This period tends to last a shorter time for younger and better nourished women and longer the more live births a woman has had and the more she breastfeeds. Women will also cease having periods if they have a hysterectomy, where the uterus is removed, and at menopause, the natural end of menstruation.

Hormonal Causes

• A number of hormonal disorders may cause a woman to miss her period. Polycystic ovary syndrome -- a condition where women tend to be overweight, have excessive amounts of body hair and have abnormally high levels of hormones -- may prevent a woman from menstruating. An overactive or underactive thyroid or a pituitary tumor may disrupt a woman's hormones enough that she does menstruate. A woman may also stop having periods if she goes through premature menopause, where her egg supply declines before the age of 40.

Stress

• Stress can result in the cessation of menstrual periods. Mental stress affects the hypothalamus, the part of the brain controlling a woman's reproductive hormones. If the stress is severe it may interfere with normal hormonal function enough that she misses her period. Extreme exercise or excessive weight loss, such as from an eating disorder, can also place a severe enough strain on a woman's body to disrupt her menstrual cycles. These abnormal reasons for missing a period can be reversed when the stress ends.

Medications

• Some medications may cause a woman to miss her period as a natural side effect. Hormonal birth control methods -- such as birth control pills, the patch and intrauterine devices -- may prevent a woman from menstruating. Even after stopping birth control pills, a woman may not resume normal menstrual cycles for three to 12 months. Other drugs that can cause a woman to stop menstruating include antidepressants, blood pressure medication and chemotherapy.

Structural Abnormalities

• Sometimes women have abnormalities in their reproductive organs that keep them from menstruating. If a woman has a congenital problem where her uterus, ovaries or vagina is missing, she won't be able to have periods. Scarring in the uterine tissue because of fibroid treatment or a cesarean section can damage the uterine lining enough to prevent normal menstruation. Abnormalities in the vagina, such as a membrane blocking the cervix or no opening to the vagina, may also interfere with a woman's ability to have a period.