What is polycystic ovary syndrome (PCOS)?

Polycystic ovary syndrome (PCOS) affects a woman’s menstrual cycles and fertility.

Women with PCOS have trouble with ovulation, the monthly release of egg cells by the ovaries. Typically, an egg cell grows in a follicle (also called a cyst), which fills with fluid. When the egg is ready, the follicle breaks open and the egg is released and can be fertilized.

In women with PCOS, the follicle does not always break open and release the egg. Instead, it may remain as a cyst on the ovary. Over time, many cysts can develop.

While the exact cause of PCOS isn’t known, scientists believe that imbalances of hormones – particularly androgens and insulin – are involved.

Androgens are a type of sex hormone usually associated with men. Testosterone is one type of androgen. Women’s bodies make androgens too, but in much smaller amounts.

The bodies of women with PCOS make more androgens than they may need. High levels of androgens can interfere with ovulation.

High levels of insulin, a hormone that helps the body process and/or store blood sugar, may also be involved with PCOS. Experts think that insulin is related to androgen production. So, if a woman has too much insulin, her body might make more androgens.

Many women with PCOS have trouble getting pregnant. In fact, PCOS is believed to be the most common reason for female infertility.

Other issues associated with PCOS include:

  • Hirsutism (increased hair growth). Excess hair may grow on the face, chest, thighs, abdomen, stomach, back, toes, or thumbs.
  • Obesity. According to the American College of Obstetricians and Gynecologists, up to 80% of women with PCOS are obese.
  • Acanthosis nigricans. Areas of thick, dark skin may form on the neck, arms, breasts, or thighs.

Women with PCOS may also have acne, oily skin, and thinning hair.

PCOS could be hereditary. Many women with PCOS have a mother or sister with the condition.

It is estimated that between 5% and 10% of women have PCOS.

Currently, PCOS has no cure, but treatments are available. Treatment for PCOS is usually based on a woman’s symptoms and whether or not she would like to become pregnant.


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