If your period doesn't make its monthly appearance, your first emotion may be joy if you're trying to get pregnant. But while pregnancy is a common cause of a missed period, it's not the only one: In fact, an irregular or skipped period happens to up to a quarter of all women of childbearing age.
There are a number of reasons why your period may not show up on time — or at all. Missed-period culprits are often as simple as a shift in your schedule or a bout of illness. However, since an irregular or skipped period can also indicate a more serious underlying medical condition, such as thyroid disease or another hormonal imbalance, it's smart to stay on top of it and, if it persists, get it checked out.
Is it normal to miss a period?
There are certain times when it's not uncommon for your period to be irregular or not appear at all, including the first few years after menstruation starts, during pregnancy and while breastfeeding.
You may also skip a period at the end of your menstrual years as you approach menopause. During this time, it's not unusual for your period to wax and wane, sometimes disappearing for months, until it stops completely. (You're technically in menopause when you've gone over 12 months without a menstrual period.)
Possible causes of a late or missed period
Pregnancy
Sometimes a late period means exactly what you think: You're pregnant! Because many of the earliest pregnancy symptoms — including cramps, bloating, nausea, spotting, fatigue, breast tenderness and even food aversions — can be similar to what you may experience in the days before menstruation, it can be difficult to tell if your cycle is simply off by a few days or if you're pregnant.
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The fastest and easiest way to find out if pregnancy is the cause of your missed period is to take an at-home pregnancy test. These tests detect human chorionic gonadotropin (better known as hCG, a hormone released during pregnancy) in your urine. Pregnancy tests are most reliable the day after your missed period, but some brands claim to detect pregnancy up to five days before your period is due.
Stress
You already know that stress can trigger a number of unpleasant side effects, like headaches, weight gain and acne, so it should come as no surprise that it can also affect your menstrual cycle. When you're under physical or emotional stress, your body produces the hormones adrenaline and cortisol. Elevated levels of these stress hormones force the brain to decide which bodily functions are essential and which are nonessential until the anxiety-inducing event is over.
Stress won't typically cause problems with your cycle, but occasionally too much stress can lead to fluctuations in hormone levels, which could in turn mess with your body's timing of ovulation and delay your period.
Illness
Certain illnesses, such as a cold or the flu, can also stress the body and impact ovulation, and, as a result, your period. If illness around the time of ovulation caused you to skip a period, it will likely reappear as normal next cycle.
Weight
Your weight can affect your hypothalamus, a gland in the brain responsible for regulating various processes in the body — including your menstrual cycle.
Extreme weight loss, low caloric intake or being very underweight can stress the hypothalamus. This could inhibit your body from producing the estrogen needed to build the lining of the uterus.
On the other hand, being overweight or gaining a lot of weight in a short amount of time can cause your body to produce too much estrogen. An overload may result in a few months without ovulation or cause the endometrial lining to overgrow and become unstable, resulting in heavy, irregular or missed periods.
Usually, consulting your doctor and gaining a healthy amount of weight if you're underweight or losing if you're overweight should help your periods to return to normal.
Excessive exercise
Of course, working out is good for you. However, when you overdo it (and possibly also restrict meals to lose weight), your body may not produce enough estrogen to complete the menstrual cycle.
Some women — such as ballet dancers, gymnasts and professional athletes — are at greater risk for amenorrhea (missing a period for three or more months in a row). But you don't have to be a pro for exercise to mess with your system. Working out excessively without taking in enough calories can also cause disruptions.
Some possible signs that you're overdoing it? Extreme or rapid weight loss, decreased physical performance, or forcing yourself to work out through injury, illness or severe weather. Slowing down a bit and gaining weight if needed should get things back on track.
Change in schedule
Believe it or not, switching things up — for instance, working the night shift instead of the day, or traveling across the country — can throw off your internal body clock, which helps regulate your hormones. Sometimes this results in a missed or late period, but it should return when your body gets used to the change or your schedule goes back to normal.
Breastfeeding
If you're breastfeeding, you may not get your period for some time, since prolactin — the hormone responsible for breast milk production — also suppresses ovulation.
Many moms don't have a period for months (or at all) while breastfeeding. But a lapse in your cycle doesn't mean you can't get pregnant. Remember, ovulation occurs before you get your period. It's possible for you to ovulate and then get pregnant before you ever see your period.
Most moms should see their periods return within six to eight weeks after weaning. If you haven't gotten your period three months after you stop breastfeeding, talk to your doctor.
Medication
Probably the most common medication to cause menstrual changes is birth control. Hormonal contraceptives such as the pill or patch work by stopping the body from ovulating — and no ovulation means no period. But what about that monthly bleeding you have while using one of these methods? What you're really experiencing is withdrawal bleeding, a "fake" period caused by the drop in hormones when you take the placebo pills in your pack or go patch-free during the fourth week of your cycle.
Sometimes, though, birth control suppresses hormones so much that you have very light bleeding or no period at all during that week off. And some pills are even designed to stop your period for a longer amount of time (three months or more). Other hormonal birth controls, such as the Depo-Provera shot or the IUD, thin the lining of the uterus to such a degree that there may be no lining to shed monthly.
Emergency contraception, or the morning after pill, can also affect when or if you ovulate, so if you've taken it recently you may experience a late or skipped period. (Bring this up with your doctor.)
Some other medications that can cause your period to be irregular include antidepressants, some antipsychotics, corticosteroids and chemotherapy drugs.
If you've recently gone off the pill in the hopes of getting pregnant, you may notice that it takes a month or so for your cycle to regulate itself — in which case a skipped period might just be your system getting back on track. If you're not sure whether you might be pregnant, however, visit your doctor.
Hormonal imbalance
Polycystic ovary syndrome (PCOS) is a condition where the female sex hormones are out of balance. PCOS can cause cysts on the ovaries and prevent ovulation from occurring regularly. In addition to missed or irregular periods, PCOS can also contribute to excess hair growth, acne, weight gain and possibly infertility.[1]
Your doctor can do a blood test to check your hormone levels if you think PCOS may be the reason for your menstruation problems. If PCOS is the cause, your doctor may recommend birth control to regulate your periods.
Thyroid disorder
When the thyroid, the gland responsible for your body's metabolism, doesn't function properly, it can cause abnormal menstrual changes. An overactive thyroid (hyperthyroidism) can cause periods to be lighter and less frequent. Additional symptoms include weight loss, rapid heartbeat, increased sweating and trouble sleeping.
An underactive thyroid (hypothyroidism) may also cause periods to be less frequent but heavier. Hypothyroidism can also cause weight gain, fatigue, dry skin and hair loss.[2] A blood test can help your doctor determine if you have a thyroid disorder.
Perimenopause
The average age of menopause is 51. Anywhere from two to eight years before that, a woman experiences what's known as perimenopause, a period when the body gradually produces less estrogen. During this time, it's not uncommon to experience changes in your menstrual cycle — periods may come more or less frequently, be shorter or longer, or be lighter or heavier. But you'll also likely experience hot flashes and night sweats, sleeping difficulties, vaginal dryness and mood swings. If you're concerned about your symptoms, your doctor can check your hormone levels with a blood test.
Though a missed period can be emotional, try not to jump to conclusions until you find out what's really going on. A visit to your doctor can help pinpoint the cause, and if you're not pregnant, coax your next period along and get things back to normal.
How late can a period be?
A typical menstrual cycle lasts 28 days, but depending on the woman, a healthy cycle can be as short as 21 or as long as 35 days.[3] Track your period over several months to look for cycle patterns and changes. (There are some smartphone apps that make tracking easier.) This will help you figure out what a "normal" menstrual cycle usually looks like for you.
A period is usually considered late if it hasn't started within seven days of when you expect it. Most pregnancy tests will also be able to give you accurate results by this time.
What to do when your period is late
If your period is more than a week late and you got a negative pregnancy test, you may want to check in with your health care provider to be safe.
If your practitioner rules out any other possible concerns, it's fine to sit back and go with the flow (pardon the pun). Every woman skips a period now and then, especially if she's under stress or has been sick. Relax and do what you can to ease anxiety by eating right, getting enough sleep and exercising.
But if you go more than 90 days without a period, or you miss a period more than three times a year, your doctor should do more in-depth testing to rule out an underlying medical condition.
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