Medically reviewed by Mary Lucas, RN
Written by Our Editorial Team
Last updated 10/03/2020
So… You’re late. And not like, “Oh, it’s just a couple days” late. You’re late late.
At this point, your panic has subsided (hopefully), and you’re scouring the Internet for reasons to explain why you’re late and what it could mean.
Rather than dive into hypotheticals, let’s just get down to the details.
The technical term for what you may be experiencing is called “amenorrhea.” Basically, it’s the absence of menstruation.
And it can happen for a few different reasons — many of which are explainable and easy to understand (like stress and excessive exercising), and others that may require a conversation with your healthcare provider (like thyroid issues or, yes, pregnancy).
We know this is a stressful topic to cover, but we’re glad you came to us to learn more about what’s going on with your body.
Overall, amenorrhea is a medical term used to describe a lack of menstruation in women.
It comes in two types:
Primary amenorrhea. If you are a woman who hasn’t gotten your period by the age of 16, you’re considered to have primary amenorrhea.
Primary amenorrhea is believed to have two primary causes. The first is a hormonal imbalance as a result of issues with the pituitary gland or hypothalamus, and the second is possible chromosomal or genetic abnormalities.
Secondary amenorrhea. Secondary amenorrhea is classified as the cessation of menstruation for at least three months after a period of normal menstruating, and can happen as a result of several natural, lifestyle- and even medication-related issues, including things like pregnancy, menopause, certain hormonal birth control pills, chemotherapy drugs, crash dieting, polycystic ovary syndrome (PCOS) and plenty of others.
The most common natural cause of amenorrhea is pregnancy.
A missed period — even if you’re using birth control — could signal pregnancy. If you’ve had sex and forgot to take one of your pills, took a pill late, vomited shortly after taking a pill or used medication that can interfere with birth control, you could become pregnant.
It’s worth noting that even with perfect daily use, no birth control pill is totally perfect at preventing pregnancy. When taken in the typical way, the pill is 91 percent effective at preventing pregnancy.
If you don’t get your period after several days, consider using a home pregnancy test. Even if you’re not yet experiencing clinical amenorrhea (three consecutive missed periods), these can provide fast, convenient information about whether or not you’re pregnant, although the accuracy can vary based on how early you take the test after missing your period.
If you don’t want to use a home pregnancy test, don’t trust the results or simply want to meet with an expert, talk to your healthcare provider. Your doctor will be able to explain more about why you’re not getting your period and, if necessary, provide tests and treatment options.
If your test comes back negative or you simply want to familiarize with the range of possibilities, there are a number of other causes of amenorrhea to consider.
Stress can affect your body’s production of certain important hormones, affecting your menstrual cycle and potentially causing you to miss your period.
The relationship between stress and hormone production is complicated. However, experts think that mental stress can affect the way your hypothalamus — a part of the brain that's responsible for regulating the production of certain hormones — functions.
Exercising too frequently, or at an extreme intensity level, may cause you to miss your regular period — a condition called exercise-induced amenorrhea.
There are several reasons for this. The first is that intense exercise releases stress hormones, which, as we noted above, may affect the areas of your brain responsible for producing a range of hormones related to your menstrual cycle.
The second is that certain types of exercise, such as long-duration aerobic exercise, can burn a huge amount of energy. If this energy isn’t replaced through extra calories from food, your body can enter into a “starvation state” in which non-essential bodily functions slow down or stop.
Now, this doesn’t mean that exercising will cause you to lose your period, or that exercise isn’t a good thing.
In fact, exercise itself doesn’t cause amenorrhea — instead, it’s the effects of intense exercise on stress hormones and energy intake that can cause your period to stop.
If you’re an athlete or just like to exercise often and notice that your period hasn’t started when it should, it’s best to talk to a healthcare professional. They’ll be able to let you know if you’re exercising too hard or eating too little to fully recover from your training.
Losing a large amount of weight in a short amount of time, such as from a highly restrictive diet, may cause you to stop getting your period.
If you’ve significantly reduced your caloric intake in order to lose weight, gone on a “cleanse”-type diet that discourages eating food or just eaten less and exercised more in order to lose weight, you may notice your period stopping.
Although missed periods are often linked to anorexia and other eating disorders, you don’t need to be underweight to miss your period due to dieting and weight loss.
In fact, in one 1989 study, researchers found that menstrual disturbances can occur after dieting even in women with a normal, healthy body weight.
Amenorrhea due to weight loss can also occur after surgical procedures designed to lower your weight, such as gastric bypass surgery.
In a 2017 study, researchers found that the majority of women who stopped getting a regular period after weight loss surgery got it back within a year.
If you’ve recently lost weight and don’t seem to get your period at the normal time, contact your healthcare provider.
Depending on your specific situation, they may recommend adjusting your eating habits or taking other steps to make sure you have a healthy, regular menstrual cycle.
Sometimes, missed periods can also occur due to rapid weight gain and/or obesity. Research shows that while most overweight and obese women have normal menstrual cycles, obesity is often linked to menstrual dysfunctions that can affect your period and fertility.
If you’re overweight or obese — or have recently gained a significant amount of weight — and don’t have a regular period, talk to your healthcare provider.
They may recommend a combination of dietary and lifestyle changes to help you lose weight and maintain good menstrual health.
If you have hyperthyroidism (an overactive thyroid), hypothyroidism (an underactive thyroid) or another health condition that affects your production of thyroid hormones, your menstrual cycle may be affected, causing you to stop getting a regular period.
This can occur because overly high or low levels of thyroid hormones can affect the hormones that cause you to ovulate.
Thyroid issues may also affect your body’s production of prolactin — one of several hormones that can stop you from ovulating.
If you have hyperthyroidism (an overactive thyroid), you may notice a faster-than-normal heart rate, increased appetite, sweating and feelings of nervousness and anxiety. You may also find that you lose weight easily, even if you eat a reasonable amount of food.
If you have hypothyroidism (an underactive thyroid), you may notice that you often feel fatigued, have overly dry skin, gain weight easily and have an increased level of sensitivity to the cold.
If you suspect that a thyroid problem might be causing you to miss your period, it’s important to talk to your doctor. Thyroid problems are easily detected via testing, with treatments available to either increase or reduce your level of thyroid hormones.
Polycystic ovary syndrome, or PCOS, is a common condition that affects about one in every 10 women of childbearing age. It’s caused by a hormonal imbalance and can affect your menstrual cycle by disrupting the development and release of eggs.
If you have PCOS, you may notice that you don’t get your period regularly, or that you don’t get a period at all for several months at a time. As well as missed periods, PCOS can cause other symptoms, such as acne, weight gain, thinning hair and excessive body hair growth.
Interestingly, the birth control pill often improves certain symptoms of PCOS, particularly those related to your menstrual cycle.
If you’re worried that you might have PCOS, it’s best to talk to your doctor. Your doctor may be able to detect PCOS and recommend a range of treatment to help you maintain a more regular menstrual cycle.
If you missed consecutive periods or qualify for amenorrhea and can’t work out why, the first thing to do is not panic. Seriously. Our bodies can be weird sometimes, and even if our cycles are typically pinpoint accurate, sometimes things go awry.
If you use the birth control pill or another form of hormonal contraception with a 28-day cycle, your period should come at roughly the same time every 28 days.
It’s also normal for your natural menstrual cycle (i.e., when you are not on hormonal contraception) to vary in length if you’re in your teens and have only recently started getting your period, or if you’re in your 40s or 50s when you’re approaching menopause.
All that said, if you can’t quite figure out why you’re experiencing amenorrhea, contact your healthcare provider. They’ll be able to help you figure out what’s going on and help put your mind at ease.