Illustration by Emma Günther
Why is my period late?
Exploring potential reasons
Top things to know:
Menstrual cycles can vary in length by up to 7–9 days
There are several health-related reasons why your period could be late
Unpredictable periods are common and expected during different life stages, including around menarche and before menopause
If you’ve had unprotected sex and your period is late, you should take a home pregnancy test
Tracking with Clue can help you learn when to expect your period
When you’re expecting your period and it doesn’t show up, it can feel unsettling. You might start thinking, “When did I last have sex? Did I use protection? Could my birth control have failed? Am I pregnant?” Before you start to spiral, take a deep breath and read this.
Your body is not a clock. The number of days between your periods may vary, especially if you are a teenager, breastfeeding, or nearing menopause. Stress, travel, diet, illness, and medication (including birth control) can also affect your cycle. As an adult, your menstrual cycle can vary in length by up to 7–9 days (1).
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How late is “late?”
It can be hard to know if your period is late if you don’t know the average length of your cycle or when your last period was. If you’ve been tracking your period over the past few months, you’ll have a better idea of your average cycle length. Here’s what to keep in mind:
If your period is about 10 days later than usual, it might be considered late.
If you haven’t had your period for 90 days or more, it’s considered missed. This is also called amenorrhea (2).
If you’re tracking with Clue, you’ll know your cycle length, variability, and when your next period is predicted to start. You can set a reminder to let you know when your period is coming and to alert you if it’s late.
What to do if your period is late
If you’ve had sex that could lead to pregnancy (or any type of sperm exposure to your vulva) and your period is late, you should take a pregnancy test. Whether the test is positive or negative, it’s a good idea to speak to your healthcare provider. A negative result doesn’t rule out other factors that might be affecting your cycle.
There are many reasons, besides pregnancy, that could cause a delayed period. Your healthcare provider can help you sort out what may be causing your irregular periods. If you haven’t had a period for more than 90 days, speak with your provider, even if you haven’t been sexually active (2). Keep reading to learn more about other reasons your period might be late.
How soon will a pregnancy test work?
Pregnancy tests work by checking your blood or urine for a hormone called human chorionic gonadotropin (hCG). This hormone has to be at a certain level to be detected by a pregnancy test (3). The earlier you take a test, the less accurate it may be. For the most accurate result, it’s recommended to take a pregnancy test 1–2 weeks after your missed period (4). If you don’t want to wait that long, you can consider taking it two weeks after your last unprotected sexual encounter.
If you get a negative result at first and still haven’t had your period, you can take another pregnancy test a few days later or if you’re unsure you took it correctly you can also repeat the test (4). Seek advice from your healthcare provider if you’re uncertain of your test result.
What do I do if I’m pregnant?
If your pregnancy test is positive, it’s important to make a plan. A first step can be meeting with a trusted healthcare provider. If you want to continue the pregnancy, it’s recommended to start taking prenatal vitamins as soon as possible to help maintain a healthy pregnancy (5). If you are unsure about continuing the pregnancy, a healthcare provider can guide you through the process.
Here are some online resources for both pregnancy care and abortion services:
USA: ACOG, ACNM, Planned Parenthood
UK: National Health Service (NHS) (Pregnancy & Reproductive Services)
Australia: Family Planning Alliance, Pregnancy Birth & Baby
New Zealand: Family Planning
Canada: Canadian Federation for Sexual Health (CFSH), Pregnancyinfo.ca
If you are transgender or nonbinary, there are many organizations worldwide that can help you find a trans-friendly OB/GYN.
Why is my period late but I’m not pregnant?
There are several health-related reasons your period might be late, even if you’re not pregnant. Here are some common reasons and how they might affect your cycle:
Stress
High levels of stress can throw off your hormone balance, which may delay your period (6). When you’re stressed, your body produces more cortisol, a hormone that can interfere with the hormones regulating your menstrual cycle (7-9). High cortisol levels have been linked to unpredictable or delayed periods (10,11).
Excessive exercise
Excessive/extreme exercise or sudden changes in physical activity can influence your hormone production (9,12). When you push your body too hard without giving it enough energy, it may prioritize essential functions over maintaining a regular menstrual cycle. This energy shortage can cause your period to become unpredictable or delayed (9).
Weight loss
Significant changes in your body weight can impact your menstrual cycle (9,13). If you lose weight quickly, whether from dieting or eating disorders like anorexia or bulimia, your body might not get the energy it needs to keep your cycle regular. This lack of nourishment can throw off your hormones, leading to unpredictable periods or even causing them to stop entirely (9,13).
Weight gain
Similarly, gaining weight can also affect your cycle, especially if it leads to obesity (a BMI greater than or equal to 30) (14,15). Extra fat tissue produces more estrogen, which can disrupt the balance between estrogen and progesterone (14). This hormonal shift may lead to delayed or unpredictable periods (14). If you're noticing significant changes in your weight, along with changes in your cycle, reach out to your healthcare provider. They can help determine if there are other underlying reasons for the weight changes that may be affecting your cycle and recommend healthy strategies to manage your weight.
Health conditions
Certain health conditions like polycystic ovary syndrome (PCOS), hypothyroidism, hyperthyroidism, or diabetes can affect your cycle (16-18). These conditions interfere with hormone levels or the way your body processes hormones. If you have one of these medical conditions, your cycle might be unpredictable, and periods can be delayed or missed (16-18).
Medications and birth control
Medications that contain hormones, such as hormonal birth control and hormone therapy, can change your cycle by interfering with the hormones that control it (19). Starting, stopping, or changing birth control methods can lead to unpredictable bleeding as your body adjusts to the new hormone levels (19). Some forms of long-acting birth control, including hormonal IUDs, the shot, and the implant, may cause your periods to stop altogether (19).
If you’re using hormonal birth control and do not experience a withdrawal bleed when you normally would, consider taking a pregnancy test if there’s any chance you could be pregnant (for example, if you missed a pill). Other medications, such as certain antidepressants and antipsychotics, have also been linked to menstrual cycle changes (20,21).
Puberty
During puberty, your body is still learning how to manage its hormones. It’s common for periods to be unpredictable, and for your cycles to vary in length during the first couple of years after menarche (your first period) (22). Although a few missed or delayed periods are typical during this time, reach out to your healthcare provider if your cycles are shorter than 21 days, longer than 45 days, or if you go 90 days or more without a period (22).
Breast/chest feeding
When you’re breast/chest feeding, your body produces higher levels of prolactin to help with milk production (23). This hormone can sometimes suppress ovulation, leading to fewer periods or delays in your cycle (24). Unpredictable cycles are common as your body shifts from the postpartum phase back to its typical cycle (23).
Perimenopause
In the years leading up to menopause (known as perimenopause), your hormones can fluctuate a lot. These changes can make your cycles shorter, longer, or unpredictable (25). Along with other experiences like hot flashes or night sweats, irregular periods are typical during this transition (25).
When should I see a healthcare provider?
While changes in your cycle can be expected during different life stages, you should talk to your healthcare provider if (1):
Your period is more than 10 days late and there is a chance you could be pregnant.
You’re between the ages of 18–25 or 42–45, and the difference between your shortest and longest cycles is greater than 9 days.
You’re between the ages of 26–41, and the difference between your shortest and longest cycles is greater than 7 days.
You haven’t had a period for more than 90 days, regardless of age or sexual activity.
You notice other unusual changes or symptoms that concern you.
How can tracking my period help?
Understanding your menstrual cycle baseline—what’s typical for you—is important. It can be an indicator of your body’s functions and overall health (22). It’s also helpful to track details such as:
The number of days you bleed.
How heavy or light your bleeding is.
Any pain you experience leading up to and during your periods.
How you feel emotionally.
The amount of sleep you get.
Medications and birth control you take.
Your energy level, sex drive, and sexual encounters.
A late period can make you feel emotional, but try not to jump to conclusions until you find out what’s really going on. It’s completely normal for the length of your menstrual cycle to vary sometimes—maybe it’s nothing at all.
Download Clue to track your period, your menstrual experiences, and more.
FAQs
What causes lighter-than-usual menstruation?
Hormonal changes, certain medications (including hormonal birth control), stress, or certain health conditions can sometimes result in lighter or infrequent bleeding (6,16-19).
Why is my period late but I have cramps?
It’s possible to experience cramps even if your period is late. Scientists believe that cramps may be caused by an excess of prostaglandins, hormone-like compounds released from the uterine lining before your period starts (26). Cramps might also be related to hormonal fluctuations or reproductive conditions like endometriosis or adenomyosis (27). If your cramps are severe, or happen outside your usual menstrual cycle, reach out to your healthcare provider (27).
How can I make my period come?
There’s no guaranteed way to “force” your period to arrive. Instead, focus on reducing stress, eating a balanced diet, and getting enough rest. If you’re worried, reach out to your healthcare provider.
