Oligomenorrhea (or oligomenorrhoea) is infrequent (or, in occasional usage, very light) menstruation. More strictly, it is menstrual periods occurring at intervals of greater than 35 days, with only four to nine periods in a year. Also, menstrual periods should have been regularly established previously before the development of infrequent flow. The duration of such events may vary.
Oligomenorrhea can be a result of prolactinomas (adenomas of the anterior pituitary). It may also be caused by thyrotoxicosis, hormonal changes in perimenopause, Prader–Willi syndrome, and Graves disease. "Endurance exercises such as running or swimming can affect the reproductive physiology of women athletes. Female runners, swimmers and ballet dancers menstruate infrequently in comparison to nonatheletic women of comparable age or not at all (amenorrhea). The degree of menstrual abnormality is directly proportional to the intensity of the exercise. For example, Malina et al., (1978) have shown menstrual irregularity is more common, and more severe among tennis players than among golfers" (modified by a student paper written by A. Lord) Breastfeeding has also been linked to irregularity of menstrual cycles due to hormones which delay ovulation.
Women with polycystic ovary syndrome (PCOS) are also likely to suffer from oligomenorrhea. PCOS is a condition in which excessive androgens (male sex hormones) are released by the ovaries. Women with PCOS show menstrual irregularities that range from oligomenorrhea and amenorrhea, to very heavy, irregular periods. The condition affects about 6% of premenopausal women and is related to excess androgen production.
Eating disorders can also result in oligomenorrhea. Although menstrual disorders are most strongly associated with Anorexia nervosa, Bulimia nervosa may also result in oligomenorrhea or amenorrhea. There is some controversy regarding the exact mechanism for the menstrual dysregulation, since amenorrhea may sometimes precede substantial weight loss in some anorexics; thus some researchers hypothesize that some as-yet unrecognized neuroendocrine phenomenon may be involved, and the menstrual irregularities may be related to the biological undergirding of the disorders, rather than a result of nutritional deficiencies.
^Frisch RE; Gotz-Welbergen AV; McArthur JW et al. (1981). "Delayed menarche and amenorrhea of college athletes in relation to age of onset of training". JAMA246 (14): 1559–1563. doi:10.1001/jama.246.14.1559. PMID7277629.Cite uses deprecated parameter |author-separator= (help)
^Warren MP (1980). "The effects of exercise on pubertal progression and reproductive function in girls". J. Clin. Endocrinol. Metab.51 (5): 1150–1157. doi:10.1210/jcem-51-5-1150. PMID6775000.
^Malina RM, Spirduso WW, Tate C, Baylor AM (1978). "Age at menarche and selected menstrual characteristics in athletes at different competitive levels and in different sports". Med Sci Sports10 (3): 218–22. PMID723515.
^Pechenik, J (2007). A Short Guide To Writing About Biology. Harrisonburg: Pearson Education, Inc..
^Tăng Quang Thái (2011). "Khái niệm cơ bản về Kinh thưa". Vì mầm sống tương lai (3): www.drquangthai.wordpress.com.