Between 5 and 10 percent of reproductive-age women suffer from polycystic ovarian syndrome, or PCOS, the most common cause of infertility, according to the National Institutes of Health. PCOS is a complex syndrome with disruption of both hormonal and metabolic systems, causing a range of health problems in addition to infertility. Vigorous scientific study of PCOS suggests that the cause is extremely complex involving a combination of risk factors and genetic predisposition.
Genetics
PCOS tends to run in families, suggesting that some of the explanation for its cause may be due to genetics. PCOS is a very complex syndrome affecting steroid hormone production, ovarian follicle growth and metabolic pathways, so many potential genes could be involved, according to a review published in the July 2005 issue of "Human Reproduction Update." PCOS is probably caused by a net effect of both protective and susceptibility genes activated by an environmental trigger.
Environmental Factors
Obesity and quality of diet are two environmental factors that may interact with an underlying genetic susceptibility to cause PCOS. Obesity tends to increase the negative effect of PCOS on cycle regularity. Sisters with PCOS who were also obese had more severe menstrual cycle irregularities than normal weight sisters with PCOS. The uterine environment during pregnancy may aggravate severity of PCOS symptoms in women who were overweight infants or who were born to overweight mothers, according to "Human Reproduction Update."
A poor quality diet high in saturated fat and sugar derived toxins called advanced glycation end products found abundantly in fast food meals may contribute to insulin resistance and high androgen levels found with PCOS, according Doctors Diamanti-Kandarakis and Piper in their review of the scientific literature.
Hormonal Imbalances
Women with PCOS produce an excess amount of androgens such as testosterone in their ovaries. A small amount of androgen production is necessary for normal ovarian function, but excess androgens disrupt the normal process of follicle growth and release of mature eggs from the ovary, according to WomensHealth.gov. Excess androgens cause PCOS symptoms including severe acne, increased facial hair growth, increased abdominal fat distribution and problems with ovulation.
Exposure to excess androgens in the uterine environment may affect the expression of genes that control fat disposition and how insulin is used by the body, says MayoClinic.gov. High blood levels of insulin, called hyperinsulinemia, and insulin resistance are other hormonal imbalances associated with PCOS. Hyperinsulinemia is associated with elevated levels of luteinizing hormone which in turn can increase androgen production by the ovaries, disrupting normal ovarian function.
References
- Oxford Journals/Human Reproduction Update: Genetics of Polycystic Ovary Syndrome; Evanthia Diamanti-Kandarakis and Christina Piperi, 2005
- Womenshealth.gov: Polycystic Ovary Syndrome (PCOS)
- MayoClinic.gov: Polycystic ovary syndrom:causes
- National Institutes of Health: Beyond Infertility: Polycystic ovarian syndrome
