Female Fertility + Health

What Causes Polycystic Ovarian Syndrome (PCOS)?

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A diagnosis of polycystic ovarian syndrome (PCOS) is more common than you may think. In fact, roughly 1 in 10 women all over the world experience some or all of the symptoms, caused by an imbalance of reproductive hormones. This hormonal disparity creates all sorts of issues in the ovaries, making PCOS one of the most common — yet treatable — causes of infertility. What do you need to know about PCOS, especially if you’re trying to get pregnant? We break it down for you here.

What is Polycystic Ovarian Syndrome?

PCOS affects about 5 to 15 percent of women of childbearing age, and occurs among all races and nationalities. It is the most common hormonal disorder among women of reproductive age, and is a leading cause of infertility.

PCOS is characterized by:

  • Irregular menstrual cycles.
  • Elevated levels of male hormones.
  • Ovaries that contain many small “cysts” or fluid filled sacs.

Many women with PCOS also experience issues with insulin resistance, and are at an increased risk for diabetes.

In a normal menstrual cycle, a single follicle (or fluid filled sac containing an immature egg) is selected for and increases in size until it bursts and releases a mature egg. But with PCOS, the eggs in these follicles do not mature properly. Instead of being released during your menstrual cycle, the follicles build up in the ovaries and create a “string of pearls” appearance. So, if you have PCOS, then you are not necessarily ovulating and releasing an egg each month, making it common for you to have irregular or missed periods.

What Causes PCOS?

The exact cause of PCOS is unknown. Polycystic ovarian syndrome is called a syndrome rather than a disease because it refers to a group of symptoms, rather than an established condition with a known cause. Although the ovaries of women with this syndrome contain a higher than normal number of small follicles, women without PCOS may also have ovaries with a similar appearance. For this reason, researchers believe the cysts themselves are not causing the problem.

Does PCOS Have a Genetic Link?

PCOS tends to run in families, and it’s likely that there is a genetic predisposition. However, there is no known “PCOS gene.” Many studies are currently investigating the genetic causes of PCOS.

Other factors that may play a role in the development of PCOS are:

Excess androgens (male hormones): The ovaries of women with PCOS produce higher than normal amounts of androgens, which can interfere with the development and release of eggs.

Excess insulin: Insulin resistance results in increased secretion of insulin to overcome the resistance, which subsequently leads to increased androgen production.

Low-grade inflammation: Some studies have shown that women with PCOS have a low level of chronic inflammation that stimulates the ovaries to produce more androgens, as well.

Can I Get Pregnant if I Have PCOS?

The good news here is YES! Infertility due to PCOS is typically due to lack of regular ovulation. However, this can be treated with oral medications that promote ovulation. Many women also experience a return of regular menstrual cycles with weight loss, and are able to conceive without medications. However, it’s also important to note that not all women with PCOS have difficulty becoming pregnant.

Dr. Sydney Chang is a Fellow in Reproductive Endocrinology and Infertility at the Icahn School of Medicine at Mount Sinai/Reproductive Medicine Associates of New York.  She earned her Bachelor of Arts in Human Biology at Stanford University, where she graduated with Honors and Distinction. She went on to complete her medical school education at Duke University School of Medicine. She completed her residency in Obstetrics, Gynecology, and Women’s Health at the Albert Einstein College of Medicine, where she served as an administrative chief resident. 

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