When most of us complain about our periods, we kvetch about those heavy flow days and the bloating, cramping, and exhaustion that can go along with them. So if your period suddenly becomes very light the whole time, it might seem like a good thing. While less bleeding may very well make you more comfortable, it could be a sign something’s gone awry. (An unusually heavy period can also be cause for concern.)
FYI, the scientific term for abnormally low bleeding is hypomenorrhea. While most periods produce between 30 to 50 mL, a person with hypomenorrhea is producing substantially less than 30 mL per cycle, according to the book Clinical Methods: The History, Physical, and Laboratory Examinations. It’s pretty difficult to measure out your period in mL, but this is just a point of reference.
Lina Akopians, MD, PhD, a specialist in reproductive endocrinology at the Southern California Reproductive Center, says that a period that lightens up substantially could be caused by a hormonal issue or a structural one (meaning something happened to an organ in your body). Here are 8 reasons that might explain why your flow is so light.
Admit it: You’ve watched at least one episode of the TLC series, I Didn’t Know I Was Pregnant, and you probably thought the women were crazy. How could someone grow a baby for 9 months and not have a clue?
While we can’t explain why they didn’t notice that their bellies were getting rounder, some about-to-be-moms remain in the dark for pretty long simply because they’ve been taught that as long as they’re getting periods, there’s no way they could be pregnant. Turns out, that’s wrong.
Although most women stop getting periods once they conceive, some continue to experience bleeding, says fertility expert Janet Choi, MD, medical director at CCRM in New York. In fact, she’s had patients who’ve been struggling to get pregnant go out drinking after a light version of their period shows up—only to later learn that they really are with child.
Unusually light periods or spotting could also indicate an ectopic pregnancy (when an egg implants somewhere other than the uterus), which can be very dangerous. When in doubt, take a pregnancy test.
You’ve lost or gained a ton of weight.
Despite being capable of carrying another human being to term, your body’s chemistry is really quite delicate, and when you add or subtract a bunch of poundage from it, it can freak out. One of the ways that manifests is by denying you your monthly visit from Auntie Flow, or by making those visits a lot shorter or lighter. While this may seem like a positive, Akopians notes that “your body needs a healthy balance between protein, carbohydrates, fats, and vitamins” if you want it to keep operating normally.
You’re stressed to the max.
While the usual day-to-day annoyances like having a fight with your spouse or blowing a presentation at work aren’t enough to throw your hormones out of whack, Choi says that major life stressors—for example, your parents dying—can do just that. She also points out that over-exercising can also wreak havoc on your period because of the stress it puts on your body, physically.
You have an overactive thyroid.
The thyroid gland is located in the front of your neck, just below your voice box, and releases hormones that control various bodily functions like temperature and digestion. An overactive thyroid—also known as hyperthyroidism—begins producing too many thyroid hormones, which can cause serious issues for your heart, blood pressure, muscles, and more. Abnormally light periods are also a symptom of hyperthyroidism, as well as missing your periods entirely. You may even be able to feel the nodules pushing against your neck. If you’re experiencing some of the symptoms of an overactive thyroid, make an appointment to see your doctor.
You’re using hormonal birth control.
One of the most common reasons for a lighter period is going on the birth control pill; some doctors even prescribe it to women with very heavy periods for that exact reason. If you’ve recently started the pill or gotten a hormonal IUD like Mirena and your periods have lightened up, just enjoy it.
You have polycystic ovary syndrome.
PCOS is a condition where the ovaries produce an abnormally large amount of androgens, which are male sex hormones. Some (but not all) women with PCOS will have small fluid-filled sacs, or cysts, form in the ovaries. These hormonal changes can prevent a woman from ovulating normally, which can lead to a host of unpleasant symptoms, including acne or oily skin, weight gain, and excess body hair. Another common symptom of PCOS is periods that are much lighter than usual; irregular and missed periods are common as well. Talk with your doctor if you’re experiencing these kind of symptoms; usually, treatment will involve some kind of medication.
You’re getting older.
Don’t worry—this doesn’t mean you’re old! But when a patient mentions a diminishing return on her tampon investment, the first thing Choi looks at is age. Menopause might be around the corner, but not always. “Sometimes with aging the cycles change,” she says, noting that it’s not necessarily a sign of infertility. “Someone who needed to use a super pad in their 20s and early 30s may find they need less protection in their later 30s.”
You have cervical stenosis.
A rare but uncomfortable problem, Akopians says this occurs when the cervix narrows or closes up completely. As a result, blood stays trapped in the uterus or is only able to trickle out slowly. If you have bad cramping despite a light flow, talk to your doctor.
You have scar tissue in your uterus.
Most women who have gone through routine dilation and curettage (D&C) procedures heal with zero complications, but sometimes severe scarring causes the walls of the uterus to stick to each other, causing what’s known as Asherman’s syndrome. If your period seems to have lightened up a lot after you’ve had a D&C, this might be your problem. You may need surgery to remove the scar tissue.
You lost a ton of blood during or after childbirth.
“This is a very rare condition,” says Akopians. Losing a lot of blood deprives your body of oxygen, which can end up damaging the pituitary gland and causing something called Sheehan’s syndrome. That, in turn, drastically reduces the gland’s production of hormones, including those that control your menstrual cycle. You’ll probably need hormone replacement therapy.
The bottom line: While having a lighter period than normal isn’t necessarily cause for alarm, don’t ignore the change. Track your cycle for a couple of months, and if it doesn’t go back to “your” normal, make an appointment with your gynecologist.