As many as 10 percent of women of childbearing age are believed to be affected by endometriosis, a chronic inflammatory condition in which the tissues that are meant to line the uterus proliferate in areas outside of it as well. In the United States alone, endometriosis costs over $49 billion in healthcare and lost working days — not to mention that it can significantly lower patients' quality of life.
Being nulliparous — not having given birth to a baby
Women who have never delivered a baby are more likely than those with children to have severe endometriosis, and childless women with endometriosis also have a much higher risk of developing ovarian cancer than either those with the condition who have had children or those who don't have endometriosis.
That's not to say that getting pregnant and having children will prevent you from developing endometriosis, or that it will send your symptoms packing if you have already been diagnosed. Decades ago, doctors often advised endometriosis patients to get pregnant to treat their endometriosis, but the fact that pregnancy can lead to a temporary improvement in symptoms because of the different hormones involved doesn't mean you will be free from endometriosis after you give birth.
Endometriosis sufferers who would like to get pregnant should be aware that — although they may see some symptom improvement — their condition does expose them and their babies to some additional risks. Vaginal bleeding during pregnancy and in the postpartum period and preterm birth are two examples. Women who have a c-section may also find that they develop endometrial lesions in the scar.
Starting your period young
Early menarche may sound like a strange risk factor — until you hear that your risk of endometriosis goes up with the number of periods you've had. Women who had their first periods early, before they turned 11, are thus slightly more likely to develop the condition. This increased risk, research shows, is small, but it still exists.
A short menstrual cycle
In endometriosis, the tissue that should only line the uterus, the endometrium, also grows in other areas of the reproductive system and beyond. Like the normal uterine lining, these extra-uterine endometrial lesions wax and wane throughout the menstrual cycle, with the difference that they can't all be expelled during menstruation. It is no surprise that this leads to more heavy and painful periods that also often last longer, but endometriosis can also lead to shorter menstrual cycles (lasting less than 27 days) as well as vaginal bleeding between periods.
The idea that so-called retrograde menstruation, in which some of the menstrual flow finds it way upward rather than out of the body, is behind endometriosis is one of the main theories. Some degree of retrograde menstruation isn't abnormal, but if you suffer from a medical condition that leads to larger volumes of retrograde menstruation, your risk of developing endometriosis can go up.
Examples of such conditions include:
- High estrogen levels
- Uterine abnormalities, or vaginal or cervical malformations
- Benign uterine growths — polyps or fibroids
Immune system disorders
There is a significant degree of overlap between endometriosis and certain immune system disorders. Having one of the following disorders makes it more likely you will have endometriosis:
- Irritable bowel syndrome
- Rheumatoid arthritis
- Celiac disease
Endometriosis runs in families — if one of your close female relatives (mother, sister, grandmother) has the condition, you're up to 10 times more likely to develop it yourself. Even having extended relatives with endometriosis increases your risk somewhat, and you may be surprised to hear you shouldn't just be on the lookout for maternal relatives, as having a female relative with endometriosis on your father's side also makes it more likely you will have it.
Research confirms that underweight women, those with a low body mass index, are more at risk of developing endometriosis than overweight and obese women. You have to ask whether being underweight contributes to endometriosis or the other way around, though, as one study indicates that endometriosis makes women more likely to lose weight.
A history of pelvic or abdominal surgery
You have probably heard that endometrial lesions easily implant themselves into scar tissue. Abdominal surgeries, like a cesarean section or a tubal ligation, cause such scar tissue. Endometrial cells can also end up in other parts of the reproductive system during a pelvic operation, possibly causing endometriosis if your immune system doesn't rid your body of these cells.
Bad news, ladies. A large analysis of previous research indicated that drinking alcohol boosts your risk of endometriosis. You don't need to be a heavy drinker either, as even moderate alcohol consumption is associated with this risk. It isn't yet clear whether drinking can also increase the severity of existing endometriosis lesions or symptoms, but you may consider cutting well down on alcohol anyway.
The pesticides mirex and beta HCH have been banned in modern industrial countries for a long time now, but they remain in the environment. Eating certain fish or consuming dairy products may expose you to these pesticides, and research has found that exposure greatly increases a woman's odds of developing endometriosis. In-utero exposure to other chemicals, which disturb your hormonal balance, has also been shown to make it more likely that you will develop endometriosis.