16 Reasons Why You Missed Your Period

A missed period could mean you're pregnant, but there might be another cause

Pregnancy is by far the most common cause of a missed period. However, other medical and lifestyle factors can also affect your menstrual cycle and make your period late.

If you're not pregnant, then weight changes, hormonal irregularities, and menopause are among the most common causes of a missed period. With these issues, you may miss a period for one or two months, or you may experience complete amenorrhea—meaning no period for three or more months in a row.

A normal menstrual cycle (the day your period starts to the first day of your next period) is about 28 days. However, a normal cycle could be up to 38 days. If your cycle is longer than this, or longer than is usual for you, it's considered late.

This article explores 16 common reasons your period may be delayed.

reasons for a missed or late period

Verywell / Cindy Chung


Intense stress interrupts the production of gonadotrophin-releasing hormone (GnRH)—a hormone that regulates ovulation and the menstrual cycle.

Both physical and psychological stress can cause a delayed period. But the level of stress capable of causing this effect is usually more severe than having a bad day.

Missing one period while going through a very stressful situation is not uncommon. However, if you're under prolonged stress and miss three or more periods, consider scheduling a visit with your healthcare provider (and asap if the stress is overwhelming).

If there is no other medical reason for your missed period, your healthcare provider may suggest counseling to help you cope with your situation. Once your stress is back to a manageable level, it may take a few months or more for your cycles to become regular again.

Polycystic Ovary Syndrome (PCOS)

People with polycystic ovary syndrome (PCOS) have a hormonal imbalance that can cause delayed or irregular periods. If you have PCOS, you will likely have other symptoms besides just an irregular menstrual cycle. Some of these may include:

  • Weight gain/trouble losing weight
  • Infertility
  • Acne
  • Hair loss or thinning
  • Hair growth on the face or body


Obesity influences estrogen and progesterone regulation and is associated with missed periods. It may even lead to issues with fertility. Weight loss can help regulate the menstrual cycle for women who are obese.

Low Body Weight

Being severely underweight interferes with regular menstrual cycles as well. When the body lacks fat and other nutrients, it cannot produce hormones the way it should.

Women who have anorexia (very low caloric intake) or who burn far more calories with exercise than what they consume may experience amenorrhea. Typically, weight gain will help your periods to return.

Rapid weight changes due to illness, medication, or dietary changes may also interfere with hormone production or release. In turn, this may cause you to miss one period or more.

Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) happens when the ovaries stop functioning normally before a person reaches the age of 40. This can cause irregular periods and fertility problems to begin before the typical age of perimenopause.

The cause of POI isn't well understood, but it is believed to be related to the function of the follicles. These are small sacs in the ovaries where eggs mature. In people with POI, there may not be enough working follicles.

Chronic Diseases

Chronic conditions that can affect your menstrual cycle include:

  • Pituitary tumors (which may or may not be cancer)
  • Diseases of the adrenal gland
  • Ovarian cysts
  • Liver dysfunction
  • Diabetes

Certain conditions that are present at birth, such as Turner syndrome and androgen insensitivity, typically cause menstrual and fertility problems. These congenital conditions are often associated with amenorrhea.

Acute Illness

Acute illness, such as pneumonia, a heart attack, kidney failure, or meningitis, can result in rapid weight loss, nutritional deficiency, or hormone dysfunction. These conditions can also result in a missed period.

Extreme Exercise

Extreme exercise can cause changes in pituitary hormones and thyroid hormones, which can impact ovulation and menstruation. Working out for one or two hours per day shouldn't affect your menstrual cycle. It usually takes hours upon hours of demanding exercise every day for these hormonal changes to occur.

If you are planning on exercising that much, you may want to consult with a sports medicine healthcare provider. Their job is to help your body support all of the physical demands that you are putting on it. This may include:

  • Optimizing your diet with nutritious foods that boost your energy
  • Teaching you stretching techniques to reduce physical stress
  • Performing blood tests to check for iron or vitamin deficiencies, hormonal imbalances, dehydration, and more


Some medications, such as antidepressants, antipsychotics, thyroid medications, anticonvulsants, and some chemotherapy medications, may cause your period to be absent or delayed.

Ectopic Pregnancy

IUDs are associated with a small chance of ectopic pregnancy. A missed period in a person with an IUD could be a sign of this dangerous condition.

Ectopic pregnancy occurs when a pregnancy implants outside of the lining of the womb. If you have a positive pregnancy test and you have an IUD in place, you should see your healthcare provider.

Symptoms of ectopic pregnancy include cramping in your lower abdomen, shoulder pain, weakness or dizziness, nausea, and breast tenderness. Some women have missed periods, while others have vaginal bleeding or spotting.

In addition to the use of an IUD, other factors that are associated with ectopic pregnancy include:

  • History of ectopic pregnancy
  • Pelvic inflammatory disease
  • Progestin-only birth control pills
  • History of sexually-transmitted infection
  • History of infertility
  • In vitro fertilization
  • Smoking
  • Fallopian tube scarring, possibly due to pelvic surgery or appendix rupture

Ectopic pregnancy is a life-threatening condition. Seek medical attention right away if you miss your period and think you might be at risk.


Perimenopause is the period of transition between reproductive age and a non-reproductive age. Your periods may be lighter, heavier, more frequent, or less frequent during this time. In most cases, they'll just be different than what you're used to.

Menopause occurs when you have reached the point in your life where you will no longer ovulate or menstruate. The average age of menopause is 51 years old.

Birth Control

Hormonal contraceptives like Depo-Provera, progesterone-only MiniPill, Mirena IUD, and Nexplanon can also influence your cycle. Different types of contraceptives can affect your menstrual cycle in different ways. Some contraceptives are associated with heavy periods, some with light periods, and some with amenorrhea.

Why is my period late on birth control?

Contraceptives can help regulate your periods, but other factors including stress, diet, and changes in weight can still affect your menstrual cycle. It's also possible to experience oligomenorrhea, (infrequent or abnormally light bleeding) while using contraceptives.

Thyroid Issues

People with thyroid disease have too much or too little thyroid hormone. Thyroid hormone has many functions in the body, including menstrual cycle regulation. When you don't have the right amount of thyroid hormone, you might have periods that are irregular. Some people with thyroid disease may miss their periods altogether, often for a few months or more.

A Change in Your Schedule

Changing schedules can throw off your body clock. If you frequently change work shifts from days to nights, or if your schedule is generally all over the place, your period can be fairly unpredictable.

A change in your schedule shouldn't cause you to completely miss your period, but it can cause your period to start earlier or later than expected. Your cycle can also change by a few days if you experience jet lag.

Recently Started Periods

A normal menstrual cycle can vary. This is especially true for young women who are just starting to get their periods or for women who have not had periods for several years and are starting to menstruate again.

A young woman who has only had a few cycles may go months without another one until a regular pattern begins. And women who have not had a period due to contraceptive use, hormonal therapy, or illness may not resume regular, monthly periods right away.


You may have light periods, infrequent periods, or amenorrhea when breastfeeding, particularly if breastfeeding provides your baby with all or almost all of their calories.

Many women believe that breastfeeding is a form of birth control. While it can reduce your chances of getting pregnant, it is not 100% effective. Even if you don't have periods when you are breastfeeding, you can get pregnant. If you are not ready for another child, you should use a backup contraceptive.

When to Call Your Healthcare Provider

Missing a period every once in a while is usually not cause for concern. How much of a delay is normal for your period? It depends. On average, a menstrual cycle lasts 28 days, but 38 days could also be within the range of normal. And your cycle will change throughout your life, so at some time, you're likely to experience a late period when you're not pregnant.

That said, you should contact your healthcare provider if you miss more than one period, or if your missed period is accompanied by new or unusual symptoms.

Seek medical attention right away if you also experience any of the following:

  • New or worsening headaches
  • Vision changes
  • Nausea or vomiting
  • Fevers
  • Hair loss
  • Breast discharge or milk production
  • Excess hair growth


There are many reasons for late periods. These are often related to changes in the body that cause a hormonal imbalance, such as stress, certain illnesses, or medication. While most are not cause for alarm, you do need an evaluation and treatment if you have completely missed more than one period.

Frequently Asked Questions

  • Can you be pregnant and still have a period?

    No, you cannot have a period while you are pregnant. However, some light spotting is normal during the early stages of pregnancy. If bleeding continues or becomes heavy, it may be indicative of a serious issue.

  • What should I do if I have a late period?

    First, if you've recently had sex, take a pregnancy test. You can take a home pregnancy test as soon as you notice a missed period, or see a healthcare provider for a test.

    If you have a late period and experience any unusual symptoms, you should see a healthcare provider. Be on the lookout for new or worsened headaches, changes in vision, nausea, vomiting, fever, hair loss, breast discharge or milk production, or excess hair growth.

  • Can stress delay your period?

    Yes, stress can delay your period. People who have significant or prolonged levels of stress may experience an irregular menstrual cycle. A professional counselor or healthcare provider can offer strategies to handle high stress levels.

  • Can sex delay your period?

    No. On its own, sex cannot delay a period. A period can be delayed by becoming pregnant from sex, but protected sex should not cause it.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Robin Elise Weiss, PhD, MPH
Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.