Causes:

Dysmenorrhea

• Contraction-Causing Chemicals. Powerful chemicals known as prostaglandins and arachidonic acid can induce uterine muscle contractions. Prostaglandins also play a large role in the heavy bleeding that causes dysmenorrhea.
• Abnormal Nervous System Response. Some women with primary dysmenorrhea may have autonomic nervous systems that are overly sensitive to menstrual cycle changes. The autonomic nervous system regulates heart rate and blood pressure, and it contains the pain receptors in nerve fibers in the uterus and pelvic area. As a result, women with autonomic nervous system abnormalities may have a more intense response to pain.
• Abnormalities in the Arteries in the Uterus. Impaired blood flow through the arteries in the uterus may cause severe dysmenorrhea for some women.
• Genetic Factors. Genetic factors may play a role in primary dysmenorrhea cases.
• Endometriosis. Endometriosis is a chronic and often progressive disease that develops when the tissue that lines the uterus (endometrium) grows onto other areas, such as the ovaries, bowels, or bladder. [For more information, see In-Depth Report #74: Endometriosis.]

Endometriosis is the condition in which the tissue that normally lines the uterus (endometrium) grows on other areas of the body, causing pain and irregular bleeding.

• Uterine Fibroids. Fibroids are noncancerous growths that grow on the walls of the uterus. They can cause heavy bleeding during menstruation and cramping pain. [For more information, see In-Depth Report #73: Uterine fibroids.]
• Other Causes. Pelvic inflammatory disease, ovarian cysts, and ectopic pregnancy. The intrauterine device (IUD) contraceptive can also cause dysmenorrhea.

Abnormal Uterine Bleeding

Abnormal uterine bleeding may occur as infrequent episodes, excessive flow, prolonged duration of menses, or bleeding between menses.

Examples of abnormal bleeding include:

• Bleeding or spotting between periods
• Bleeding after sex
• Bleeding heavier or for more days than normal
• Bleeding after menopause

Dysfunctional Uterine Bleeding (DUB). DUB is a general term for abnormal uterine bleeding that usually refers to extra or excessive bleeding caused by hormonal problems. DUB usually occurs either when girls begin to menstruate or when women approach menopause, but it can occur at any time during a woman's reproductive life.

• About 90% of DUB events happen when ovulation is not occurring (anovulatory DUB). In such cases, women do not properly develop and release a mature egg. As a result, estrogen is produced continuously, causing an overgrowth of the uterus lining. The period is delayed in such cases, and when it occurs menstruation can be very heavy and prolonged.
• The other 10% of DUB cases occur in women who are ovulating (ovulatory DUB), but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding.

Other Causes of Abnormal Uterine Bleeding. Abnormal uterine bleeding may also be related to other causes unrelated to the natural cycle or ovulation:

• Uterine Fibroids. [For more information, see In-Depth Report #73: Uterine fibroids.]
• Von Willebrand Disease and Other Bleeding Disorders. Bleeding disorders that stop blood from clotting can cause heavy menstrual bleeding. Most of these disorders have a genetic basis. Von Willebrand disease is the most common of these bleeding disorders and may be underdiagnosed in many women with unexplained menorrhagia.
• Abnormalities in the Uterus. Structural problems or other abnormalities in the uterus may cause bleeding. They include uterine polyps (small benign growths in the uterus), uterine fibroids, endometriosis, adenomyosis, and miscarriage. Infections or inflammation in the vagina or pelvic area can also cause heavy bleeding.
• Medications and Contraceptives. Certain drugs, including anticoagulants and anti-inflammatory medications, can cause heavy bleeding. Problems linked to some birth control methods, such as birth control pills or intrauterine devices (IUDs) can cause bleeding.
• Cancer. Rarely, uterine, ovarian, and cervical cancer can cause excessive bleeding
• Infection. Infection of the uterus or cervix can cause bleeding.
• Pregnancy or Miscarriage.
• Other Medical Conditions. Systemic lupus erythematosus, diabetes, pelvic inflammatory disorder, cirrhosis, and thyroid disorders can cause heavy bleeding. Women who have migraine headaches may be more likely to have menorrhagia and endometriosis.

Fibroid tumors may not need to be removed if they are not causing pain, bleeding excessively, or growing rapidly.

Amenorrhea and Oligomenorrhea

Normal causes of skipped or irregular periods include pregnancy, breast-feeding, hormonal contraception, and perimenopause. Skipped periods are also common during adolescence, when it may take a while before ovulation occurs regularly. Consistently absent periods may be due to the following factors:

• Delayed Puberty. A common cause of primary amenorrhea is delayed puberty due to some genetic factor that delays physical development. Failure of ovarian development is the most common cause of primary amenorrhea.
• Hormonal Changes and Puberty. Oligomenorrhea is a frequent complaint during puberty who are just beginning to have their periods
• Weight Loss and Eating Disorders. Another common cause of amenorrhea in adolescent girls is eating disorders. Extreme weight loss and reduced fat stores lead to hormonal changes that include low thyroid levels (hypothyroidism) and elevated stress hormone levels (hypercortisolism). These changes produce a reduction in reproductive hormones. A syndrome known as the female athlete triad is associated with hormonal changes that occur with the combination of eating disorders, amenorrhea, and osteopenia (loss of bone density that can lead to osteoporosis) in young women who excessively exercise.
• Polycystic Ovarian Syndrome (PCOS). PCOS is a condition in which the ovaries produce high amounts of androgens (male hormones), particularly testosterone. PCOS occurs in about 10% of women of childbearing age, and amenorrhea or oligomenorrhea (infrequent menses) is quite common.
• Elevated Prolactin Levels (Hyperprolactinemia). Prolactin is a hormone produced in the pituitary gland that stimulates breast development and milk production in association with pregnancy. High levels of prolactin (hyperprolactinemia) in women who are not pregnant or nursing can reduce gonadotropin hormones and inhibit ovulation, thus causing amenorrhea.
• Premature Ovarian Failure (POF). POF is the early depletion of follicles before age 40. In most cases, it leads to premature menopause. POF is a significant cause of infertility.
• Structural Problems. In some cases, structural problems or scarring in the uterus may prevent menstrual flow. Inborn genital tract abnormalities may also cause primary amenorrhea.
• Stress. Physical and emotional stress may block the release of luteinizing hormone, causing temporary amenorrhea.
• Athletic Training. Amenorrhea or oligomenorrhea associated with vigorous activity is related to stress and not weight loss. Female athletes who use anabolic steroids will often have amenorrhea or oligomenorrhea.

• Other Medical Conditions. Epilepsy, thyroid problems, celiac sprue, metabolic syndrome, and Cushing's disease are associated with amenorrhea.

If the ovaries produce too much androgen (hormones such as testosterone) a woman may develop male characteristics. This ovarian imbalance can be caused by tumors in the ovaries or adrenal glands, or polycystic ovarian disease. Virilization may include growth of excess body and facial hair, amenorrhea (loss of menstrual period) and changes in body contour.