Having no menstrual periods is called amenorrhea.
Amenorrhea is normal in the following circumstances:
Before puberty
During pregnancy
While breastfeeding
After menopause
At other times, it may be the first symptom of a serious disorder.
Amenorrhea may be accompanied by other symptoms, depending on the cause. For example, women may develop masculine characteristics (virilization), such as excess body hair (hirsutism Hairiness In men, the amount of body hair varies greatly (see also Overview of Hair Growth), but very few men are concerned enough about excess hair to see a doctor. In women, the amount of hair that... read more 
), a deepened voice, and increased muscle size. They may have headaches, vision problems, or a decreased sex drive. They may have difficulty becoming pregnant.
In most women with amenorrhea, the ovaries do not release an egg. Such women cannot become pregnant.
If amenorrhea lasts a long time, problems similar to those associated with menopause Menopause Menopause is the permanent end of menstrual periods and thus of fertility. For up to several years before and just after menopause, estrogen levels fluctuate widely, periods become irregular... read more 
may develop. They include hot flashes, vaginal dryness, decreased bone density (osteoporosis Osteoporosis Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more 
), and an increased risk of heart and blood vessel disorders. Such problems occur because in women who have amenorrhea, the estrogen level is low.
Types of amenorrhea
There are two main types of amenorrhea:
Primary: Menstrual periods never start.
Secondary: Periods start, then stop.
Usually if periods never start, girls do not go through puberty, and thus secondary sexual characteristics, such as breasts and pubic hair, do not develop normally.
If women have been having menstrual periods, which then stop, they may have secondary amenorrhea. Secondary amenorrhea is much more common than primary.
Hormones and menstruation
Menstrual periods are regulated by a complex hormonal system Overview of the Female Reproductive System . Each month, this system produces hormones in a certain sequence to prepare the body, particularly the uterus, for pregnancy. When this system works normally and there is no pregnancy, the sequence ends with the uterus shedding its lining, producing a menstrual period Menstrual Cycle Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. It occurs in approximately monthly cycles throughout a woman's reproductive life, except during... read more . The hormones in this system are produced by the following:
The hypothalamus (part of the brain that helps control the pituitary gland)
The pituitary gland, which produces luteinizing hormone and follicle-stimulating hormone
The ovaries, which produce estrogen and progesterone
Other hormones, such as thyroid hormones and prolactin (produced by the pituitary gland), can affect the menstrual cycle.
The most common reason for no menstrual periods in women who are not pregnant or breastfeeding is
Malfunction of any part of this hormonal system
When this system malfunctions, the ovaries do not release an egg. The type of amenorrhea that results is called anovulatory amenorrhea.
Less commonly, the hormonal system is functioning normally, but another problem prevents periods from occurring. For example, menstrual bleeding may not occur because the uterus is scarred or because a birth defect, fibroid, or polyp blocks the flow of menstrual blood out of the vagina.
High levels of prolactin, which stimulates the breasts to produce milk, can result in no periods.
Causes
Amenorrhea can result from conditions that affect the hypothalamus, pituitary gland, ovaries, uterus, cervix, or vagina. These conditions include hormonal disorders, birth defects, genetic disorders, and drugs.
Which causes are most common depends on whether amenorrhea is primary or secondary.
Primary amenorrhea
The disorders that cause primary amenorrhea are relatively uncommon, but the most common are
A genetic disorder
A birth defect of the reproductive organs that blocks the flow of menstrual blood (such as an imperforate hymen Imperforate hymen Defects of the genitals can involve the penis, scrotum, or testes (testicles) in boys and the vagina and labia in girls. Sometimes the genitals are ambiguous, that is, not clearly female or... read more
)
Genetic disorders include
Overproduction of male hormones by the adrenal glands (congenital adrenal hyperplasia Congenital adrenal hyperplasia Defects of the genitals can involve the penis, scrotum, or testes (testicles) in boys and the vagina and labia in girls. Sometimes the genitals are ambiguous, that is, not clearly female or... read more
)Genital disorders Genital Birth Defects Defects of the genitals can involve the penis, scrotum, or testes (testicles) in boys and the vagina and labia in girls. Sometimes the genitals are ambiguous, that is, not clearly female or... read more
that result in ambiguous—neither male nor female—genitals (pseudohermaphroditism or true hermaphroditism)Disorders that result in having a Y chromosome (which normally occurs only in males).
Genetic disorders and birth defects that cause primary amenorrhea may not be noticed until puberty. These disorders cause only primary amenorrhea, not secondary.
Sometimes puberty is delayed in girls who do not have a disorder, and normal periods simply begin at a later age. Such delayed puberty may run in families.
Secondary amenorrhea
The most common causes are
Pregnancy
Breastfeeding
Malfunction of the hypothalamus
Malfunction of the pituitary gland or the thyroid gland
Use of certain drugs, such as birth control pills (oral contraceptives), antidepressants, or antipsychotic drugs
Pregnancy is the most common cause of amenorrhea among women of childbearing age.
The hypothalamus may malfunction for several reasons:
Stress or excessive exercise (as done by competitive athletes, particularly women who participate in sports that involve maintaining a low body weight)
Poor nutrition (as may occur in women who have an eating disorder Overview of Eating Disorders Eating disorders involve a disturbance of eating or of behavior related to eating, typically including Changes in what or how much people eat Measures people take to prevent food from being... read more or who have lost a significant amount of weight)
Mental disorders (such as depression Depression A short discussion of prolonged grief disorder. Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to... read more or obsessive-compulsive disorder Obsessive-Compulsive Disorder (OCD) Obsessive-compulsive disorder is characterized by obsessions, compulsions, or both. Obsessions are recurring, persistent, unwanted, anxiety-provoking, intrusive ideas, images, or urges. Compulsions... read more )
Radiation therapy or an injury
The pituitary gland may malfunction because
It is damaged.
Levels of prolactin are high.
Antidepressants, antipsychotic drugs, oral contraceptives (sometimes), or certain other drugs can cause prolactin levels to increase, as can pituitary tumors and some other disorders.
The thyroid gland may cause amenorrhea if it is underactive (called hypothyroidism Hypothyroidism Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions. Facial expressions become dull, the voice... read more 
) or overactive (called hyperthyroidism Hyperthyroidism Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more 
).
Less common causes of secondary amenorrhea include chronic disorders (particularly of the lungs, digestive tract, blood, kidneys, or liver), some autoimmune disorders, cancer, HIV infection, radiation therapy, head injuries, a hydatidiform mole (overgrowth of tissue from the placenta), Cushing syndrome, and malfunction of the adrenal glands. Scarring of the uterus (usually due to an infection or surgery), polyps, and fibroids can also cause secondary amenorrhea.
Genetic disorders, such as Fragile X syndrome Fragile X Syndrome Fragile X syndrome is a genetic abnormality on the X chromosome that leads to intellectual disability and behavior problems. Chromosomes are structures within cells that contain DNA and many... read more , may cause menstrual periods to stop early (premature menopause Premature Menopause Premature menopause is the permanent end of menstrual periods before age 40. It occurs because the ovaries no longer release eggs (ovulation) regularly and become less able to produce hormones... read more ).
Evaluation
Doctors determine whether amenorrhea is primary or secondary. This information can help them identify the cause.
Warning signs
Certain symptoms are cause for concern:
Delayed puberty
Development of masculine characteristics, such as excess body hair, a deepened voice, and increased muscle size
Vision problems
A milky nipple discharge Nipple Discharge Fluid that leaks from one or both nipples is called a nipple discharge. Each breast has several (15 to 20) milk ducts. A discharge can come from one or more of these ducts. (See also Overview... read more that occurs spontaneously (that is, without the nipple's being squeezed or otherwise stimulated)
A significant change in weight
When to see a doctor
Girls should see a doctor within a few weeks if
They have no signs of puberty (such as breast development or a growth spurt) by age 13.
Periods have not started by age 15 in girls who are growing normally and have developed secondary sexual characteristics.
Such girls may have primary amenorrhea.
If girls or women of childbearing age have had menstrual periods that have stopped, they should see a doctor if they have
Missed 3 menstrual periods
Fewer than 9 periods a year
A sudden change in the pattern of periods
Such women may have secondary amenorrhea. Doctors always do a pregnancy test when they evaluate women for secondary amenorrhea. Women may wish to do a home pregnancy test before they see the doctor.
What the doctor does
Doctors first ask about the medical history, including the menstrual history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of amenorrhea and the tests that may need to be done (see table Some Causes and Features of Amenorrhea Some Causes and Features of Amenorrhea 
).
For the menstrual history, doctors determine whether amenorrhea is primary or secondary by asking the girl or woman whether she has ever had a menstrual period. If she has, she is asked how old she was when the periods started and when the last period occurred. She is also asked to describe the periods:
How long they lasted
How often they occurred
Whether they were ever regular
How heavy they were
Whether her breasts were tender or she had mood changes related to periods
If a girl has never had a period, doctors ask
Whether breasts have started to develop
Whether she has had a growth spurt
Whether pubic and underarm hair (signs of puberty) has appeared
Whether any other family member has had abnormal periods
This information enables doctors to rule out some causes. Information about delayed puberty and genetic disorders in family members can help doctors determine whether the cause is a genetic disorder.
Doctors ask about other symptoms that may suggest a cause and about use of drugs, exercise, eating habits, and other conditions that can cause amenorrhea.
During the physical examination, doctors determine whether secondary sexual characteristics have developed. A breast examination is done. A pelvic examination is done to determine whether genital organs are developing normally and to check for abnormalities in reproductive organs.
Doctors also check for symptoms that may suggest a cause such as
A milky discharge from both nipples: Possible causes include pituitary disorders and drugs that increase levels of prolactin (a hormone that stimulates milk production).
Headaches, hearing loss, and partial loss of vision or double vision: Possible causes include tumors of the pituitary gland or hypothalamus.
Development of masculine characteristics, such as excess body hair, a deepened voice, and increased muscle size: Possible causes include polycystic ovary syndrome, tumors that produce male hormones, and use of drugs such as synthetic male hormones (androgens), antidepressants, or high doses of synthetic female hormones called progestins.
Hot flashes, vaginal dryness, and night sweats: Possible causes include premature menopause, a disorder that causes the ovaries to malfunction, radiation therapy, and use of a chemotherapy drug.
Shakiness (tremors) with weight loss or sluggishness with weight gain: These symptoms suggest a thyroid disorder.
Testing
In girls or women of childbearing age, the first test is
A pregnancy test
If pregnancy is ruled out, other tests are done based on results of the examination and the suspected cause.
If girls have never had a period (primary amenorrhea) and have normal secondary sexual characteristics, testing begins with ultrasonography to check for birth defects that could block menstrual blood from leaving the uterus. If birth defects are unusual or difficult to identify, magnetic resonance imaging (MRI) may be done.
Tests are usually done in a certain order, and causes are identified or eliminated in the process. Whether additional tests are needed and which tests are done depend on results of the previous tests. Typical tests include
Blood tests to measure levels of prolactin (to check for conditions that cause high levels), thyroid hormones (to check for thyroid disorders), follicle-stimulating hormone (to check for pituitary or hypothalamus malfunction), and male hormones (to check for disorders that cause masculine characteristics to develop)
Imaging tests of the abdomen and pelvis using computed tomography (CT), MRI, or ultrasonography to look for a tumor in the ovaries or adrenal glands
Examination of chromosomes in a sample of tissue (such as blood) to check for genetic disorders
Viewing of the uterus and usually fallopian tubes (hysteroscopy Hysteroscopy Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more
or hysterosalpingography Hysterosalpingography Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more ) or imaging tests to check for blockages in these organsUse of hormones (estrogen and a progestin or progesterone) to try and trigger menstrual bleeding
For hysteroscopy, doctors insert a thin viewing tube through the vagina and cervix to view the interior of the uterus. This procedure can be done in a doctor's office or in a hospital as an outpatient procedure.
For hysterosalpingography, x-rays are taken after a substance that can be seen on x-rays (a radiopaque contrast agent) is injected through the cervix into the uterus and fallopian tubes. Hysterosalpingography is usually done as an outpatient procedure in a hospital radiology suite.
If hormones trigger menstrual bleeding, the cause may be malfunction of the hormonal system that controls menstrual periods or premature menopause. If hormones do not trigger bleeding, the cause may be a disorder of the uterus or a structural abnormality preventing menstrual blood from flowing out.
If symptoms suggest a specific disorder, tests for that disorder may be done first. For example, if women have headaches and vision problems, MRI of the brain is done to check for a pituitary tumor.
Treatment
When amenorrhea results from another disorder, that disorder is treated if possible. With such treatment, menstrual periods sometimes resume. For example, if an abnormality is blocking the flow of menstrual blood, it is usually surgically repaired, and periods resume. Some disorders, such as Turner syndrome and other genetic disorders, cannot be cured.
If women have a Y chromosome, doctors recommend surgical removal of both ovaries because having a Y chromosome increases the risk of ovarian germ cell cancer Ovarian Cancer . Ovarian germ cell cancer starts in the cells that produce eggs (germ cells) in the ovaries.
If a girl's periods never started and all test results are normal, she is examined every 3 to 6 months to check on the progression of puberty. She may be given a progestin and sometimes estrogen to start her periods and to stimulate the development of secondary sexual characteristics, such as breasts.
Problems associated with amenorrhea may require treatment, such as
Treating symptoms and long-term effects of an estrogen deficiency (for example, by taking vitamin D, consuming more calcium in the diet or in supplements, or taking drugs, including hormone therapy and drugs that prevent bone loss such as bisphosphonates Drugs
or denosumab for fractures caused by osteoporosis)
Key Points
Various conditions can disrupt the complex hormonal system that regulates the menstrual cycle, causing menstrual periods to stop.
Doctors distinguish between primary amenorrhea (periods have never started) and secondary amenorrhea (periods started, then stopped).
The first test is a pregnancy test.
Unless a woman is pregnant, other testing is usually required to determine the cause of amenorrhea.
Problems related to amenorrhea (such as a low estrogen level) may also require treatment to prevent later health problems.
