Ovarian cysts can happen for a variety of reasons. They commonly develop due to ovulation or certain health conditions, like endometriosis or polycystic ovary syndrome (PCOS). Ovarian cysts can also form due to abnormal cell growth, pregnancy, or, in rare cases, ovarian cancer. 

This article provides an overview of ovarian cysts’ most common causes and lifestyle risk factors.

Common Causes

Several types of ovarian cysts can develop as a result of different causes, which include ovulation, pregnancy, PCOS, and more.

Ovulation

As part of the body’s reproductive system, the ovaries produce the eggs released each month during the ovulation stage of the menstrual cycle. Ovarian cysts most commonly form when:

  • The follicle (or sac) that the egg grows in does not break open to release the egg but instead continues to fill with fluid. This produces what is known as a follicular cyst.
  • The follicle (or sac) that the egg grows in does not dissolve but continues to grow. This produces what is known as a corpus luteum cyst.

Pregnancy

One type of ovarian cyst, a corpus luteum cyst, is common during pregnancy. It develops during ovulation, forming from follicular cells that store thyroid hormones to be released into the bloodstream, and is meant to break down or dissolve.

But in some cases, this ovarian cyst does not dissolve and grows during pregnancy.

Endometriosis

Ovarian cysts also commonly develop in people with endometriosis, a condition that causes tissue to develop abnormally outside the uterus. If the tissue attaches to the ovaries, it can form an ovarian cyst.

PCOS

People with PCOS, a hormonal disorder, often have many small follicles on their ovaries. This is because the condition causes the ovaries to enlarge and follicles to arrange on the outer lining of the organ, creating a polycystic appearance.

Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is an infection that affects the reproductive organs. It typically happens when a sexually transmitted infection (STI) spreads to the ovaries and the fallopian tubes.

It can also occur as a complication of pelvic or gynecologic surgery. As a result, an abscess or pus-filled cyst can form involving the ovary.

Noncancerous Growths

Other benign (not cancerous) ovarian cysts can develop on the outside surface of the ovaries. Known as dermoid cysts or teratomas, they’re often made of reproductive cells and sometimes hair, fat, or teeth.

Cancer

In rare cases, cancer can be a cause of ovarian cysts. These chances are less likely in people who menstruate and may be slightly more common in people who have reached menopause (when a person no longer gets a menstrual period).

Genetics

Experts believe certain types of ovarian cysts have a genetic component. Research indicates that dermoid ovarian cysts appear to run in families. Older studies have shown that you’re more likely to develop a dermoid ovarian cyst if you have an immediate family member with a history of those cysts.

Some researchers estimate that up to 7% of people develop an ovarian cyst in their lifetime.

In addition, genetics also plays a role in conditions like PCOS, which can lead to the development of ovarian cysts. People with PCOS often have a family member who also has the condition. Researchers have identified variations in specific genes that may be responsible for PCOS in combination with other factors.

Lifestyle Risk Factors

Certain factors may make it more likely for an ovarian cyst to develop. Lifestyle risk factors for ovarian cysts include hormonal imbalances and pregnancy.

Some hormonal changes can prompt the development of ovarian cysts. Fertility treatments that cause a person to ovulate may increase the chances of an ovarian cyst developing.

Throughout pregnancy, it’s possible for the follicle that formed during ovulation to stay on the ovary, causing an ovarian cyst.

In addition, the chances of developing an ovarian cyst are higher in:

  • Menstruating peoplePeople who have a history of ovarian cystsPeople who have endometriosis, PCOS, or a severe pelvic infection

Summary

Fluid-filled growths known as ovarian cysts can form on the ovaries for various reasons. Most commonly, ovarian cysts form due to the ovulation process during the menstrual cycle. Other causes include having certain health conditions (such as PCOS, endometriosis, and severe pelvic infections) or pregnancy. Rarely can ovarian cysts be caused by cancer. Experts are still studying a potential genetic link for developing certain ovarian cysts.

Ovarian cysts are quite common and can develop during the reproductive years or postmenopause. Most arebenign and often resolve themselves without treatment. It’s important to always check with a healthcare provider to get a proper diagnosis and treatment plan if needed.

A Word From Verywell

If you’ve been diagnosed with an ovarian cyst, know you’re not alone. While they’re usually harmless, it’s still a good idea to check with a healthcare provider about how often you should receive routine pelvic exams.

Frequently Asked Questions

  • What causes a cyst on the ovary?
  • Ovarian cysts commonly develop during the ovulation part of the menstrual cycle. They can also form due to hormonal imbalances, pregnancy, genetic factors, abnormal cell production, or health conditions like endometriosis, PCOS, and inflammatory pelvic disease.
  • Learn More:
  • Causes of Ovary Pain and Treatment Options

Ovarian cysts commonly develop during the ovulation part of the menstrual cycle. They can also form due to hormonal imbalances, pregnancy, genetic factors, abnormal cell production, or health conditions like endometriosis, PCOS, and inflammatory pelvic disease.