Definition
Medical dictionaries define oligomenorrhea as infrequent or very light menstruation. But physicians typically apply a narrower definition, restricting the diagnosis of oligomenorrhea to women whose periods were regularly established before they developed problems with infrequent flow. With oligomenorrhea, menstrual periods occur at intervals of greater than 35 days, with only four to nine periods in a year.
Description
True oligomenorrhea cannot occur until a young woman's menstrual periods have been established. In the United States, 97.5 percent of women have begun normal menstrual cycles by age 16. The complete absence of menstruation (menstrual periods never started or they stopped after having been established) is called amenorrhea. Oligomenorrhea can be redefined as amenorrhea if menstruation stops for six months or more; however, there is no universally agreed-upon cutoff point or timeline.
It is quite common for women at the beginning and end of their reproductive lives to miss periods or have them at irregular intervals. This variation is normal and is usually the result of imperfect coordination between the hypothalamus, the pituitary gland, and the ovaries. For no apparent reason, a few women menstruate (with ovulation occurring) on a regular schedule as infrequently as once every two months. For them that schedule is normal and not a cause for concern.
Women with polycystic ovary syndrome (PCOS) are also likely to suffer from oligomenorrhea. PCOS is a condition in which the ovaries become filled with small cysts. Women with PCOS show menstrual irregularities that range from oligomenorrhea and amenorrhea to very heavy and irregular periods. PCOS affects about 6 percent of premenopausal women and is related to excess androgen production.
Other physical and emotional factors also cause a woman to miss periods. These include the following:
- emotional stress
- chronic illness
- poor nutritional status
- such eating disorders as anorexia nervosa
- excessive exercise
- estrogen-secreting tumors
- abnormalities in the structure of the uterus or cervix that obstruct the outflow of menstrual fluid
- illicit use of anabolic steroid drugs to enhance athletic performance
Professional ballet dancers, gymnasts, and ice skaters are especially at risk for oligomenorrhea because they combine strenuous physical activity with a diet intended to keep their weight down. Menstrual irregularities are known to be one of the three disorders comprising the so-called "female athlete triad," the other disorders being disordered eating and osteoporosis. The triad was first formally named at the annual meeting of the American College of Sports Medicine in 1993, but doctors were aware of the combination of bone mineral loss, stress fractures, eating disorders, and participation in women's sports for several decades before the triad was named. Women's coaches have become increasingly aware of the problem since the early 1990s and are encouraging female athletes to seek medical advice.
