Short Period Causes: 10 Potential Reasons Your Monthly Flow Was Shorter Than Normal
Most things in life are uncertain, but when it comes to your period, you can usually count on its friendly appearance once a month. What constitutes a “normal” period is pretty individualized, but what happens when your period is shorter than what's normal for you?
Shorter periods can be NBD (if your period lasts two to three days, and it’s always lasted two to three days, no biggie), but it’s important to pay attention to your cycle, and note any changes, says Alyssa Dweck, MD, an ob-gyn and author of The Complete A to Z for Your V.
After all, the length of your period is largely determined by hormonal factors, says Lakeisha Richardson, MD, an ob-gyn based in Greenville, Mississippi. That means everything from medications to underlying health conditions can throw off your cycle. Some of those causes are totally benign, but others are best ruled-out (or caught) early. We’ll get into those soon, but first, there are a few other factors to consider when it comes to irregular periods.
For one, changes in your cycle length can sometimes be a cause for concern, says Caitlin McCarthy, MD, an ob-gyn with Axia Women’s Health. "Periods that are too frequent may be a sign of a structural abnormality [of the female reproductive system] or hormonal imbalance, and periods that are too infrequent can be related to an undiagnosed pregnancy, hormonal imbalances that affect ovulation, or nutritional concerns.”
Light bleeding is usually nothing to worry about, but if menstrual bleeding becomes heavy enough to cause distress or you’re concerned about your fertility, it’s time to check in with a doctor, adds Dr. McCarthy.
Curious what you’re dealing with? Ahead, doctors shed light on 10 common reasons your period might go from six days to, say, three suddenly, and when you should see a doctor.
What is a normal menstrual cycle?
Most women’s cycles last 21 to 35 days, counting from day one of one cycle to day one of the next cycle, and their periods last five to seven days on average, says Dr. Dweck. “I recommend seeing your gyno if your flow is persistently or newly varied from usual,” she adds.
FYI, "cycle length" is defined as the number of days from the start of one period to the start of the next and “duration of flow” as the number of days of actual bleeding, says Dr. McCarthy. “Both can vary from month to month and are typically nothing to worry about unless it persists over time,” she reiterates.
How much you bleed per cycle is subjective, but if it’s not disrupting your physical, emotional, and social well-being, it is typically considered “normal,” says Sameena Rahman, MD, an ob-gyn at Center For Gynecology and Cosmetics.
What causes a shorter period?
You’ve switched birth control.
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 Dr. Dweck. “Most birth control pills and rings, like the Annovera vaginal ring, lead to lighter flow,” adds Mary Jane Minkin, MD, a clinical professor of obstetrics and gynecology and reproductive sciences at Yale Medical School. “The combined hormonal contraceptives contain a good amount of progestins—synthetic progesterone—which limit the build-up of a lot of tissue lining the uterus,” she explains. As a result, there’s less of a flow when it’s go time. Progestin-only IUDs “allow a very limited buildup,” Dr. Minkin says, and many women have a lighter flow or even no period when they have one of those implanted.
Also, there could be slight hormonal differences in generic versions that could affect your cycle length, so make sure to check the packaging.
You’re on a certain type of medication.
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,” Dr. Dweck says.
The way each of these medications lighten your flow varies slightly. With NSAIDs, “the idea is that the NSAID reduces the number of inflammation compounds called prostaglandins, which in turn can lessen the amount of bleeding because prostaglandins affect the blood vessels in the inner lining of the uterus,” explains women’s health expert Jennifer Wider, MD.
Not sure if the meds you’ve taken are messing with your flow? “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," Dr. Dweck says.
You have polycystic ovarian syndrome (PCOS).
PCOS is a genetic condition where women overproduce amounts of male hormones, which can suppress ovulation and lead to changes in menstruation, says Dr. Rahman. “Women with PCOS will have a long history of irregular cycles,” adds Dr. 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.
If you think you may have primary ovarian insufficiency and want to get pregnant in the future, talk to your doc about getting tested as well as your fertility options.
You have uterine scarring.
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 Dr. 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.”
Other symptoms (aside from a short period) can vary based on the degree of scarring, but you may also develop pelvic pain during your period which is caused by the obstruction of the menstrual flow due to scarring, explains Dr. McCarthy. Additionally, uterine scarring can be associated with infertility or recurrent pregnancy loss, she adds.
This condition would be diagnosed by hysteroscopy, says Dr. 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.
You’re breastfeeding.
“Most women who are breastfeeding exclusively will not have a cycle while they are breastfeeding,” says Dr. 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.
You have an overactive thyroid.
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 Dr. Dweck. “When one aspect of the axis is disturbed, so might be other aspects.”
In other words, the hormones that play a major role in regulating periods are produced in the same region of the brain as thyroid regulating hormones, says Dr. McCarthy. “If too many thyroid hormones are produced, they provide feedback to the hypothalamus to slow down production, which also inhibits period regulating hormones.” As a result, women with hyperthyroidism may have infrequent periods or amenorrhea (a lack of periods), she adds.
Other indications of an overactive thyroid issue can include appetite and weight changes, difficulty with temperature regulation, hair changes, feelings of anxiety, and heart palpitations, according to Dr. Dweck. If you think you might have a thyroid disorder, talk to your doc about getting tested.
You have implantation bleeding.
Implantation is an early part of the pregnancy process when an embryo (i.e. fertilized egg) burrows into your uterine lining. It’s possible to bleed a little when that happens. And, if the timing lines up with your period, it’s understandable that you might think you’re having a period when you’re actually not.
“It can be difficult to tell the difference between implantation bleeding and a short period for some women because implantation can occur roughly six to 12 days after conception, which is often when a woman would expect her period,” Dr. Wider says. “The symptoms can look the same.” If there’s a chance you might be pregnant and you’re not sure what’s going on down there, take a pregnancy test to help rule pregnancy in or out, she says.
You’re really stressed out.
Stress can screw with just about everything in your life, so it’s hardly shocking that it can mess with your cycle, too. “High levels of stress can cause an increase in the production of [stress hormone] cortisol which in turn can cause a disruption in the way our bodies function normally,” Dr. Wider says.
Under normal (read: non-frazzled) times, your brain’s hypothalamus produces chemicals that trigger your pituitary gland to signal your ovaries to release estrogen and progesterone, she explains. “With an increase in cortisol from stress, that axis can get messed up and the menstrual cycle can become irregular,” Dr. Wider says.
“The less estrogen, the less stimulation of the lining of the uterus, so less bleeding,” Dr. Minkin adds.
When it comes to stress management and getting your period back on track, it’s important to find what works for *you*, whether that’s exercise , massage, acupuncture, or journaling, says Dr. McCarthy. “Don’t be afraid to speak up because stress is a part of life, and we all need help through it, so find a friend, family member, or therapist to help with [individual] coping techniques.”
You’re in perimenopause.
“As women age, their cycle may become shorter—especially as they get closer to menopause,” says Dr. Richardson. Perimenopause, the time before menopause, when your body starts transitioning hormonally, typically starts in a woman's 40s, but can start as early as the 30s. However, the average age of perimenopause is 47 and symptoms may last up to 10 years, adds Dr. Rahman.
“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, says says Dr. Richardson. But if you’re concerned, especially about your fertility, a visit to your doc certainly can’t hurt.
If you’re in perimenopause, you may also experience hot flashes, night sweats, sleep disturbances, mood swings, irritability, fatigue, weight gain, and decreased libido, says Dr. McCarthy. Additional symptoms include brain fog, depression, anxiety, dry skin, joint pain, and vaginal burning or dryness from the lack of estrogen, adds Dr. Rahman.
When To See A Doctor
A lack of period at all for more than three months when not on hormonal medications, prolonged bleeding, erratic bleeding, or heavy bleeding soaking more than two pads per hour for two consecutive hours are all red flags and should be discussed with your provider, says Dr. McCarthy. Light bleeding is rarely something to worry about, but if menstrual bleeding is heavy enough to cause distress or interfere with daily life, it is too much, she adds.
Additionally, if your period persistently becomes less or more frequent over the course of a few months, or your flow is much heavier or lighter than usual, it’s time to check in with your doc, adds Dr. Rahman. “If it’s an isolated cycle, then you can monitor, but if your period starts to cause distress, then please see a doctor where they will do a complete history and physical exam, possibly draw blood, and may also perform an ultrasound,” she explains. “Women, particularly women of color, should advocate for themselves with any bleeding issue to ensure they are appropriately heard by [their] doctor and that [they] receive the appropriate management.”