Literally 50% of the world’s population gets periods, yet many women still don’t understand their body’s reproductive cycle. What is considered a “normal” bleed? Should you get your period like clockwork every four weeks? What symptoms are considered OK, and what should you see a doctor about? What if your period just stops arriving entirely?
“If you’re not on a hormonal contraceptive of any kind, a normal cycle is anything between 21 and 35 days, and it’s normal to have variation of up to seven days between cycles,” says Kari Braaten, M.D., medical director of the Fish Center for Women’s Health at Brigham and Women’s Hospital in Boston.
Sometimes, though, the changes are more concerning—the U.S. Department of Health and Human Services estimates that 14% of women have irregular, painful, or heavy menstrual bleeding, which may indicate an underlying problem. “Anybody who bleeds more than every 21 days should see a doctor,” Dr. Braaten says, along with “anyone who’s having gaps of longer than 35 to 40 days” between periods.
If you’re concerned about your cycle, your best bet is to see a medical pro who can help you figure out exactly what’s going on. Just so you’re prepared going into your appointment, here’s a list of potential causes of your period problems.
Conditions That Affect Menstruation
First, let’s look at the different types of menstrual abnormalities. “You can divide abnormal bleeding into two broad areas,” says Steven Goldstein, M.D., a professor of obstetrics and gynecology at New York University School of Medicine in NYC.
The first are structural abnormalities, such as polyps or fibroids. The second category has to do with hormonal changes that result in a lack of ovulation. “If you don't ovulate, when exactly you will bleed depends totally on whether the estrogen production fluctuates and destabilizes the lining of the uterus,” Dr. Goldstein says. Let’s take a look at both categories, plus reasons abnormal periods could be the sign of something serious, like pre-cancer or cancer.
Endometriosis: Affecting at least 11% of women of reproductive age, endometriosis is a condition where the endmetrial cells that usually create the lining of the uterus begin to grow outside the uterus in other part of the pelvis. It can cause painful menstrual cramps, chronic abdominal pain, and occasional spotting between periods. There is no cure for endometriosis, but it can be treated with things like hormonal birth control, other medications, and surgery when necessary.
Uterine fibroids: Uterine fibroids are a common condition affecting up to 80% of women by the time they reach age 50. “Fibroids are benign tumors of the uterus,” Dr. Braaten says. “If they come close to the lining of the uterus, they cause periods to be heavier.” Fibroids often exist without any symptoms, but sometimes they can cause heavy menstrual bleeding, pain, or cramping. In severe cases, patients may choose to get fibroids removed through a hysterectomy or other surgery.
Cervical or uterine polyps: Polyps are another type of tissue growth within the wall of the uterus. They are often asymptomatic but can cause irregular bleeding and spotting. Polyps may be benign or pre-cancerous–in which case they’ll need to be removed with surgery.
Genital infection: Yeast infections, bacterial vaginosis, or STIs like chlamydia or gonorrhea may cause bleeding, itching, and unusual vaginal discharge (this has nothing to do with your menstrual cycle, but it can be confused for period spotting). Get them treated ASAP to avoid more serious complications like infertility or pelvis inflammatory disease.
- PCOS: Polycystic ovarian syndrome is a disorder of the menstrual cycle, so obviously it has a direct link to your period. “PCOS is a chronically anovulatory state,” explains Dr. Goldstein, meaning it affects your body’s ability to ovulate. The cause isn’t totally understood, but it’s related to an excess of androgen hormones, which can cause acne and excess face and body hair along with irregular periods or a lack of menstruation. Women with PCOS are often insulin-resistant, putting them at risk for type 2 diabetes—in fact, the CDC estimates that more than half of women with PCOS develop type 2 diabetes by age 40. PCOS can be treated with a combination of medication and lifestyle changes.
Thyroid disorders: “Either an overactive or underactive thyroid can affect the menstrual cycle,” Dr. Braaten says. Hyperthyroidism (an overactive thyroid) typically causes lighter or less frequent periods, while hypothyroidism (underactive thyroid) causes heavy or prolonged periods. Doctors usually look at your thyroid levels when investigating menstrual abnormalities. “When people do have heavy periods, checking their thyroid is one of the things we do at baseline,” she explains.
Chronic stress or chronic disease: Anything that puts significant stress on your body, whether it’s a chronic illness or a mental health episode, can trigger your brain to shut down its production of hormones that signal ovulation. Dr. Braaten explains that this is “often the brain’s way of saying, ‘This body is not ready to conceive a pregnancy.’”
Eating disorders or extreme exercise: These behaviors trigger the same body response as chronic stress. “Anorexia and bulimia are sources of lack of ovulation,” Dr. Goldstein says. If your body is undernourished and overworked to the point where it couldn’t support a pregnancy, you may start to menstruate less frequently (if at all).
Pre-Cancer or Cancer
Endometrial hyperplasia (pre-cancer): This is a rare condition that occurs when the lining of the uterus becomes too thick. It causes abnormal bleeding and sometimes bleeding that continues after menopause. This condition can be pre-cancerous, so it needs to be addressed ASAP with medication or surgery.
Gynecologic cancer: This is worst-case scenario, but of course you don’t want to rule out the possibility of cancer. Cervical, ovarian, uterine, and vaginal cancers can all cause heavy periods and irregular bleeding throughout the month. Your doc can help rule out this possibility.
Other Causes of Abnormal Bleeding
While having your period seems like the most likely cause of bleeding, that's actually not always the case. “There are causes of vaginal bleeding that are not related to the menstrual cycle,” Dr. Braaten says. There are also causes (like perimenopause or hormonal contraception) that aren’t a sign of any treatable health condition.
- Hormonal birth control: Anytime you start a new hormonal birth control, you’re likely to see changes in your cycle. “Pills and IUDs all affect people’s bleeding,” Dr. Braaten explains. The birth control pill works by stopping ovulation, meaning the blood you see every month isn’t actually a regular period at all, but a process brought on by the hormones in your pill. Some IUDs cause vaginal bleeding to stop entirely. Women starting a new contraceptive may experience some irregular spotting in the first few months as their body adjusts.
Injury: A cut or scratch inside your vagina (often due to sex) can cause light bleeding in the immediate aftermath.
Pregnancy: OK, it’s pretty obvious that pregnancy changes your menstrual cycle—but hey, it’s worth a mention! Women sometimes experience spotting during early pregnancy (contrary to what many people think, spotting does not necessarily indicate a miscarriage), along with nausea, swollen breasts, and fatigue.
Perimenopause: “The time around menopause is a time of menstrual changes,” Dr. Braaten says. In the five or so years before menopause, your cycle may start getting shorter, and then you’ll begin to skip periods. She explains that when your period does arrive, it should feel normal, not super heavy or painful. “If periods become super heavy or abnormal when they do come, that’s an important reason to see a doctor.”