Amenorrhea is often a sign of another health problem rather than a disease itself, and it can happen for many reasons. It can occur as a natural part of life, such as during pregnancy or breastfeeding. It can also be a sign of a health problem, such as polycystic ovary syndrome (PCOS). Because amenorrhea is associated with health conditions that are also linked to infertility, understanding amenorrhea is an important part of NICHD’s research on infertility and fertility.
What causes primary amenorrhea?
Primary amenorrhea (failure of menses to occur by age 16) can result from two main causes:
- Chromosomal or genetic abnormalities: can cause the ovaries to stop functioning normally.
- Problems with the hypothalamus or pituitary gland in the brain: can cause an imbalance of hormones that can prevent periods from starting. Conditions such as eating disorders, excessive exercise, and extreme physical or psychological stress or a combination of these factors can also disrupt the normal functioning of the hypothalamus or pituitary gland, delaying the onset of menstruation.
- physical problems: such as missing reproductive organs or blockage of reproductive passageways can also lead to primary amenorrhea. Missing portions of the reproductive tract can cause endocrine disruptions and may combine with hypothalamic or pituitary problems to prevent menstruation. Blockages may also prevent menstrual bleeding, making it seem like a girl has primary amenorrhea, even if her menstrual cycles are actually normal.
What causes secondary amenorrhea?
Secondary amenorrhea (missing three menstrual periods in a row or not having periods for at least 6 months after menstruating normally) can result from various causes, such as:
- Medications and therapies: Certain birth control pills, injectable contraceptives, and hormonal intrauterine devices (IUDs), certain antidepressants and blood pressure medications, can increase the levels of a hormone that prevents ovulation and the menstrual cycle. Chemotherapy and radiation treatments for hematologic cancer (including blood, bone marrow, and lymph nodes) and breast or gynecologic cancer can destroy estrogen-producing cells and eggs in the ovaries, leading to amenorrhea. Sometimes scar tissue can occurs after a dilation and curettage (D&C), a procedure in which tissue is removed from the uterus to diagnose or treat heavy bleeding or to clear the uterine lining after a miscarriage, a cesarean section, or treatment for uterine fibroids.
- Hypothalamic amenorrhea: This condition occurs when the hypothalamus, a gland in the brain that regulates body processes, slows or stops releasing gonadotropin-releasing hormone (GnRH), the hormone that starts the menstrual cycle. Common characteristics of women with hypothalamic amenorrhea include low body weight, low percentage of body fat, very low intake of calories or fat, emotional stress, strenuous exercise that burns more calories than are taken in through food, deficiency of leptin, a protein hormone that regulates appetite and metabolism, and some medical conditions or illnesses.
- Gynecological conditions: specifically, those that lead to or result from hormone imbalances, may also have secondary amenorrhea as a main symptom. Polycystic ovary syndrome (PCOS). Fragile X-associated primary ovarian insufficiency (FXPOI). The term FXPOI describes a condition in which a woman’s ovaries stop functioning before normal menopause.
- Thyroid problems: A thyroid gland that is overactive (called hyperthyroidism) or underactive (hypothyroidism) can cause menstrual irregularities, including amenorrhea.
- Pituitary tumors: Tumors on the pituitary gland are usually noncancerous (benign) but can interfere with the body’s hormonal regulation of menstruation.