Menstrual irregularities are changes to the menstrual cycle that result in missed periods, irregular periods, or excessive bleeding. NICHD is one of many federal agencies and NIH Institutes working to understand menstrual problems. NICHD supports and conducts research on what causes menstrual irregularities and how best to treat and detect them.
What are the symptoms of menstruation?
The primary sign of menstruation is bleeding from the vagina. Additional symptoms include:
- Abdominal or pelvic cramping
- Lower back pain
- Bloating and sore breasts
- Food cravings
- Mood swings and irritability
What are menstrual irregularities?
For most women, a normal menstrual cycle ranges from 21 to 35 days.1 However, 14% to 25% of women have irregular menstrual cycles, meaning the cycles are shorter or longer than normal; are heavier or lighter than normal; or are experienced with other problems, like abdominal cramps.2 Irregular cycles can be ovulatory, meaning that ovulation occurs, or anovulatory, meaning ovulation does not occur.
The most common menstrual irregularities include:
- Amenorrhea (pronounced ey-men-uh-REE-uh) or absent menstrual periods:3,4,5,6 When a woman does not get her period by age 16, or when she stops getting her period for at least 3 months and is not pregnant.
- Oligomenorrhea (pronounced ol-i-goh-men-uh-REE-uh) or infrequent menstrual periods: Periods that occur more than 35 days apart.4
- Menorrhagia (pronounced men-uh-REY-jee-uh) or heavy menstrual periods:3,4,7 Also called excessive bleeding. Although anovulatory bleeding and menorrhagia are sometimes grouped together, they do not have the same cause and require different diagnostic testing.7
- Prolonged menstrual bleeding: Bleeding that exceeds 8 days in duration on a regular basis.4
- Dysmenorrhea (pronounced dis-men-uh-REE-uh): Painful periods that may include severe menstrual cramps.8
Additional menstrual irregularities include:
- Polymenorrhea (pronounced pol-ee-men-uh-REE-uh): Frequent menstrual periods occurring less than 21 days apart4
- Irregular menstrual periods with a cycle-to-cycle variation of more than 20 days4
- Shortened menstrual bleeding of less than 2 days in duration4
- Intermenstrual bleeding: Episodes of bleeding that occur between periods, also known as spotting4
How many women are affected by menstrual irregularities?
Menstrual irregularities occur in an estimated 14% to 25% of women of childbearing age.1
Estimates of the number of women with menstrual irregularities may differ by the cause or nature of the irregularity. For example, if a woman experiences severe cramps, she might be included in the tally of women with endometriosis rather than in the tally of women with menstrual irregularities.
What causes menstrual irregularities?
Causes of irregular periods (generally light) include:2
- Perimenopause (generally in the late 40s and early 50s)
- Primary ovarian insufficiency (POI)
- Eating disorders (anorexia nervosa or bulimia)
- Excessive exercise
- Thyroid dysfunction (too much or too little thyroid hormone)
- Elevated levels of the hormone prolactin, which is made by the pituitary gland to help the body produce milk
- Uncontrolled diabetes
- Cushing’s syndrome (elevated levels of the hormone cortisol, used in the body’s response to stress)
- Late-onset congenital adrenal hyperplasia (problem with the adrenal gland)
- Hormonal birth control (birth control pills, injections, or implants)
- Hormone-containing intrauterine devices (IUDs)
- Scarring within the uterine cavity (Asherman’s syndrome)
- Medications, such as those to treat epilepsy or mental health problems
- Adolescence (during which cycles may not be associated with ovulation)
- Polycystic ovary syndrome (PCOS) (bleeding irregular but heavy)
- Uterine fibroids (benign growths of uterine muscle)
- Endometrial polyps (benign overgrowth of the lining of the uterus)
- Adenomyosis (the presence of uterine lining in the wall of the uterus)
- Nonhormonal IUDs
- Bleeding disorders, such as leukemia, platelet disorders, clotting factor deficiencies, or (less common) von Willebrand disease
- Pregnancy complications (miscarriage)
How do health care providers diagnose menstrual irregularities?
- Medical history
- Physical examination
- Blood tests
- Ultrasound examination
- Endometrial biopsy—a small sample of the uterus’s endometrial lining is taken to be examined under a microscope
- Hysteroscopy—a diagnostic scope that allows a health care provider to examine the inside of the uterus, typically done as an outpatient procedure
- Saline infusion sonohysterography—ultrasound imaging of the uterine cavity while it is filled with sterile saline solution
- Transvaginal ultrasonography—ultrasound imaging of the pelvic organs, including the ovaries and uterus, using an ultrasound transducer that is inserted into the vagina
What are the common treatments for menstrual irregularities?
Treatments for menstrual irregularities often vary based on the type of irregularity and certain lifestyle factors, such as whether a woman is planning to get pregnant.
- Oral contraceptives
- Cyclic progestin
- Treatments for an underlying disorder that is causing the menstrual problem, such as counseling and nutritional therapy for an eating disorder
- Insertion of a hormone-releasing intrauterine device
- Use of various medications (such as those containing progestin or tranexamic acid) or nonsteroidal anti-inflammatory medications
If the cause is structural or if medical management is ineffective, then the following may be considered:
- Surgical removal of polyps or uterine fibroids
- Uterine artery embolization, a procedure to block blood flow to the uterus
- Endometrial ablation, a procedure to cauterize (remove or close off by burning) blood vessels in the endometrial lining of the uterus
Treatment for dysmenorrhea (painful periods) include:7
- Applying a heating pad to the abdomen
- Taking nonsteroidal anti-inflammatory medications
- Taking contraceptives, including injectable hormone therapy or birth control pills, using varied or less common treatment regimens
NICHD Menstruation Research Goals
Understanding and maximizing women’s health has been part of the NICHD mission since the Institute was founded. Research on menstruation and menstrual irregularities is an important part of addressing this mission.
Fertility status is viewed as an important marker of overall health in that irregularities in the menstrual cycle, including those that affect fertility, may signal a larger health problem. As a result, NICHD research on menstruation and menstrual irregularities falls into multiple disciplines, such as reproductive endocrinology, infertility/fertility research, and reproductive and regenerative medicine, as well as specific studies of gynecological disorders that affect menstruation, such as endometriosis, uterine fibroids, and polycystic ovary syndrome.
In addition, the NICHD-funded Reproductive Medicine Network conducts large, multicenter clinical trials of diagnostic and therapeutic interventions for infertility and reproductive diseases and disorders to help advance treatment options for women affected by these conditions.
Menstruation Research Activities and Advances
NICHD conducts and supports research to learn more about normal menstruation and menstrual irregularities.