Women are born with two ovaries, one on each side of the uterus. The ovaries are part of the female reproductive system and are responsible for the production of hormones, including estrogen and progesterone.

Women can develop tumors or cysts on the ovaries. Usually these are benign, meaning not cancerous, and will stay in or on the ovaries. Less commonly, ovarian tumors are cancerous. Some ovarian tumors cause abnormal vaginal bleeding or missed periods, but it’s unlikely to be the only symptom.

Read on to learn more about the link between a missed period and ovarian cancer.

A period is considered missed when it skips an entire cycle. Most menstrual cycles are between 21 and 35 days. Cycle lengths will not vary much from month to month, but it’s not uncommon for a period to be a few days late or early. For some people, menstrual cycles are irregular and the length varies widely from month to month.

It’s a good idea to keep track of your cycle so you know your body’s rhythm. You can do this by marking a calendar or using an app such as Clue. This way you’ll know if you have regular or irregular cycles and if you miss a period. Make an appointment with your doctor if you miss your period, especially if you normally have regular cycles.

Most of the time missed periods are not a cause for concern. Pregnancy, stress, strenuous exercise, low body fat, or hormonal imbalances can cause menstrual irregularities.

In rare cases, irregular periods are a sign of something serious. They may also increase your risk of ovarian cancer. One study found that women with a history of menstrual irregularities were twice as likely to develop ovarian cancer. This risk increases with age.

Irregular or missed periods are not the most common sign of ovarian cancer. There are other, more common symptoms. Contact your doctor if you’re concerned about ovarian cancer or notice anything different in your monthly cycle.

Many women will not have symptoms in the early stages of ovarian cancer. Also, ovarian cancer symptoms are common to other conditions like irritable bowel syndrome. They may be vague and mild, which can lead to a delay in diagnosis and worse outcomes.

Make an appointment with your doctor or gynecologist if the following symptoms occur more than 12 times a month:

If you do have ovarian cancer, early diagnosis is key. Make sure you do not ignore these symptoms, especially if they persist.

Some factors can increase your risk for ovarian cancer. It’s important to understand your risk as well as the symptoms of ovarian cancer. This knowledge may help with early detection and treatment, which improves outcomes.

Risk factors for ovarian cancer include:

Age: Older women are more likely to develop ovarian cancer. More than half of women with ovarian cancer are 63 years or older.

Weight: Women who are obese have a higher risk of developing ovarian cancer. Obesity is when you have a body mass index of 30 or higher.

Race: Caucasian women are more likely than African-American women to develop ovarian cancer.

Family history: Five to 10 percent of ovarian cancers are linked to inherited changes or mutations in specific genes. One such genetic mutation is BRCA. Women with the BRCA1 mutation have a 35 to 70 percent lifetime risk of developing ovarian cancer.

No birth control: Oral contraceptives can lower your risk for ovarian cancer. The longer the use, the lower your risk, which continues even after you stop taking the pill. It takes at least three to six months of consecutive use before the benefits kick in.

Fertility drugs: Research suggests that fertility medication may increase a woman’s risk for ovarian tumors. More studies are needed, but initial research suggests that the risk is especially high for women who don’t get pregnant as a result of these fertility drugs. In addition, women who are infertile may be at increased risk of developing ovarian cancer.

Hormones: According to the American Cancer Society, estrogen therapy used after menopause may increase your risk for ovarian cancer.

Reproductive history: Women who have their first full-term pregnancy at age 35 or older or who have never had children are at a higher risk for ovarian cancer. The risk is lower for women who have children before the age of 26. The risk decreases with each full-term pregnancy, as well as with breast-feeding.

Menstrual pain: About 16 to 19 percent of women report dysmenorrhea, or moderate to severe menstrual pain. One study suggests that dysmenorrhea is associated with an increased risk of epithelial ovarian cancer. Epithelial ovarian cancer is the most common type of ovarian tumor.

Early diagnosis leads to a better outlook for ovarian cancer. About 94 percent of women who get treatment for ovarian cancer in the early stages live longer than five years after diagnosis. But only about 20 percent of ovarian cancers are discovered at an early stage. This may be because many of the symptoms are vague and nonspecific and are often ignored or attributed to other causes.

During your appointment, your doctor may conduct a pelvic exam and a Pap smear. They will do a bimanual exam to feel your ovaries for size, shape, and consistency. These exams may help with diagnosing ovarian cancer or other reproductive system cancers in the early stage.

Screening tests

Screening tests can detect a disease in people who don’t have symptoms. The two tests that can detect ovarian cancer are transvaginal ultrasound (TVUS) and the CA-125 blood test. While these tests may detect tumors before symptoms develop, they have not been proven to decrease the mortality rate of women with ovarian cancer. As a result, they are not routinely recommended for women at average risk. Currently there are no standards for ovarian cancer screening, but researchers are looking for ways to improve early detection.

Many women don’t notice symptoms until the cancer has progressed to an advanced stage. But knowing what symptoms to look for can help with early detection. Make an appointment with your doctor if you’re worried about your cancer risk or unexpectedly miss your period.