“I recommend seeing your gyno if your flow is persistently or newly varied from usual,” says Alyssa Dweck, M.D, an ob-gyn and author of The Complete A to Z for Your V. “Most women’s cycles last 21 to 35 days, counting from day one of one cycle to day one of next cycle, and their periods last five to seven days on average.”
And while Dweck notes that shorter periods can be normal (if your period lasts two to three days, and it’s always lasted two to three days, no biggie), it’s important to pay attention to your cycle, and note any changes. After all, the length of your period is largely determined by hormonal factors, says Lakeisha Richardson, an M.D. and ob-gyn based in Greenville, Mississippi. That means that everything from medications to underlying health conditions can throw your cycle off of its well, cycle. Some of those causes are totally benign, but others are best ruled-out (or caught) early.
Here, experts share the most common reasons that you period might go from six days to, suddenly, three. Rule them out the next time your period cuts out early.
If your period is suddenly breaking pattern, consider if you’ve started or changed birth control methods. “The pill might lessen the length of flow,” says Dweck. There could be slight hormonal differences in generic versions that could affect your cycle length, so make sure to check the packaging. Also, “the hormonal IUD will likely lighten your flow, and some women lose their period altogether,” she says.
Beyond the birth control pill, certain medicines could also affect your period, thanks to the chemicals in them. “NSAIDs [like Advil, Naprosyn, ibuprofen, etc.], antidepressants, thyroid medications, and steroids might shorten flow,” Dweck says. “Ruling out other causes of change in flow and taking a good medical history might lead to diagnosing medication as the cause of menstrual change.”
PCOS is a condition where women overproduce amounts of male hormones, which can suppress ovulation. “Women with PCOS will have a long history of irregular cycles,” explains Richardson. “They may also have months when they don’t have a menstrual cycle at all because of their imbalanced hormone levels.”
If you’re suffering from PCOS, you’ll likely also experience cysts on your ovaries, hirsutism (or excessive hairiness), acne, obesity, and infertility, she says. “PCOS is not a medical emergency, but seeing your ob-gyn as soon as possible to prescribe medication can help minimize the symptoms.”
(Get the secret to banishing belly bulge from WH readers who’ve done it with Take It All Off! Keep It All Off!)
“Premature ovarian failure or primary ovarian insufficiency occurs when women have loss of normal ovarian function prior to 40 years old,” explains Richardson. If your ovaries aren’t working correctly, they won’t produce the right amounts of estrogen or release eggs when they’re supposed to, which could lead to shortened and irregular cycles, she says.
Premature ovary failure typically shows up around age 27, but occurs in one in 1,000 women between the ages of 15 and 29 and one in 100 women between the ages of 30 and 39, according to RESOLVE: The National Infertility Association. “The most common symptom of premature ovarian failure is infertility and amenorrhea [loss of periods],” says Richardson, “and it’s diagnosed by ultrasound and blood test—the hormone levels would be consistent with menopause.”
Translation: If you think you may have premature ovarian failure and want to get pregnant in the future, talk to your doc about getting tested as well as your fertility options.
Scarring in the uterus can lead to shorter periods. This is known as Asherman Syndrome, a rare condition that most often occurs in women who have had multiple dilation and curettage (D&C) procedures, says Richardson. D&C’s are often used to empty the uterus following miscarriage, as an abortion method, and to treat certain gynecological conditions.
“Women who have Asherman Syndrome have shorter cycles or amenorrhea because only the areas of the uterus that are not scarred are capable of bleeding. The more scarring that is involved, the less bleeding will occur.”
This condition would be diagnosed by hysteroscopy, says Richardson, and the adhesions (or scars) would have to be removed surgically in order for your flow to return to normal and to improve your ability to conceive, if desired.
“Most women who are breastfeeding exclusively will not have a cycle while they are breastfeeding,” says Richardson. “Breastfeeding could delay ovulation for as long as 18 months, because the body is suppressing ovulation hormones by producing prolactin, alpha-lactalbumin, and lactose synthesis.” A normal cycle will return only when you stop or decrease the amount of breastfeeding, but even then, it could be shorter than normal due to the fluctuating hormones.
It sounds strange, but your thyroid can actually affect your period. “The thyroid gland is regulated in the pituitary-hypothalamus axis of the brain, as are the hormones that regulate ovulation and menstruation,” says Dweck. “When one aspect of the axis is disturbed, so might be other aspects.”
Other indications of an over- or underactive thyroid issue can include appetite and weight changes, difficulty with temperature regulation, hair changes, feelings of anxiety, and heart palpitations, according to Dweck. If you think you might have a thyroid disorder, talk to your doc about getting tested. Thyroid issues are common and treating them is important to maintaining both fertility (if that’s your thing) and overall health.
“As women age, their cycle may become shorter—especially as they get closer to menopause,” says Richardson. Perimenopause, the time before menopause, when your body starts transitioning hormonally, typically starts in women’s forties, but can start as early as the thirties. And “it can last anywhere from four to six years,” says Richardson. “During that time, women may have shorter cycles or may not have a cycle at all.” This is all perfectly normal, and there’s no need to seek medical attention during this time, she says. But if you’re concerned, especially about your fertility, a visit to your doc certainly can’t hurt.