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.
True oligomenorrhea can not occur until menstrual periods have been established. In the United States, 97.5% of women have begun normal menstrual cycles by age 16. The complete absence of menstruation, whether menstrual periods never start or whether they stop after having been established, is called amenorrhea. Oligomenorrhea can become amenorrhea if menstruation stops for six months or more.
It is quite common for women at the beginning and end of their reproductive lives to miss or have irregular periods. This 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 on the one hand to very heavy, irregular periods on the other. The condition affects about 6% of premenopausal women and is related to excess androgen production.
Other physical and emotional factors also cause a woman to miss periods. These include:
illicit use of anabolic steriod drugs to enhance athletic performance
Serious ballet dancers, gymnasts, and ice skaters are especially at risk because they combine heavy activity with a diet intended to keep their weight down. One study at the University of California San Francisco found that 11% of female ultramarathon runners had amenorrhea or oligomenorrhea. This is a much higher rate than in the general population. Women's coaches are becoming more aware of the problem and are encouraging female athletes to seek medical advice. A gynecologist is the doctor most experienced in diagnosing and treating oligomenorrhea.
Tish Davidson, The Gale Group Inc., Gale, Detroit,