10 reasons for a missed period 

It’s common to miss a period every once in a while, and it doesn’t always mean you’re pregnant. It could be from stress, nutrition, lifestyle changes, or a sign of a medical problem. Keep reading to learn 10 different causes of missed periods. 

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A missed period, medically known as amenorrhea, means you didn’t have your normal menstrual cycle for a month or longer. If your period starts later than normal but you don’t miss an entire cycle, that’s just considered a late period, not a missed period. 

On average, menstrual cycles last around 28 to 30 days, although a normal cycle length can vary significantly from person to person (Nawaz, 2021).

Here are some of the potential causes of a missed period:

1. Pregnancy

While a missed period doesn’t always mean pregnancy, it is still one of the more common causes of a missed period. If you’re sexually active and more than a week late, it’s best to take a pregnancy test to rule this cause out. Taking a test too early could result in a false negative result, so try to wait about a week after your period was supposed to start.

Other potential signs of pregnancy include:

• Nausea and vomiting

• Fatigue

• Swollen or tender breasts

• Sensitivity to smells or taste changes

2. PCOS

Polycystic ovary syndrome (PCOS) is an endocrine disorder where the ovaries release excess androgens (commonly referred to as male sex hormones, though everyone has them). Symptoms of PCOS include (Azziz, 2018):

• Missed periods and irregular menstrual cycles

• Ovarian cysts

• Excess body hair and facial hair

• Acne-prone or oily skin

• Hair loss

• Weight gain

• Infertility

• Skin tags

• Dark or thick skin patches around the neck, armpits, or breasts

3. Menopause

Menopause is a natural transition in life marked by 12 months without a menstrual cycle. Typically, this happens between the ages of 45 to 55. Some women may experience early menopause before 45 years old (Peacock, 2021). 

Perimenopause, also called the menopause transition, is the first stage and typically lasts four years before menopause. During this stage, hormone levels begin to fluctuate, causing symptoms like:

• Irregular periods and missed periods

• Hot flashes

• Mood swings

• Vaginal dryness

• Trouble sleeping

• Low sex drive

4. Being underweight or undernourished

Not enough nutrition and a very low body weight can cause missed menstrual periods. Eating disorders and problems with disordered eating, including anorexia nervosa, bulimia, and malnutrition, can cause disruptions in a normal menstrual cycle (Peacock, 2021). 

5. Hormonal birth control

Some types of hormonal birth control are designed to lighten or stop menstrual cycles. Types of contraception that may stop periods include:

• Birth control pills

• Hormonal intrauterine devices

• DMPA injection

• Vaginal rings

• Hormonal patches 

6. Stress

High stress levels are one of the more common causes of missed periods. Both emotional and physical stress can alter hormone levels, inhibiting ovulation (Fourman, 2015). 

7. Overexercising

Excessive exercise can lead to hormonal changes that impact menstruation. Studies show that amenorrhea is common in aesthetic sports, like dance, figure skating, or gymnastics (Berz, 2016).  

Missed periods from too much exercise are more common in people doing intense training for several hours a day. If you’re burning more calories than you’re eating and pushing your body to its limits, your body may respond to that stress by causing an imbalance in the hormones that keep your menstrual cycle regular. 

If you’re experiencing problems with your period and exercise intensely for many hours a week, you can generally reverse these issues by decreasing exercise intensity and increasing food intake. 

8. Certain medications

In addition to hormonal contraceptives, multiple other medications can affect your menstrual cycles, including (Fourman, 2015):

• Opioids

• Neuroleptics

• Antipsychotics

• Antidepressants

• Antihypertensives 

• Anticonvulsants

• Chemotherapy or radiation

9. Breastfeeding

After having a baby, it’s normal for it to take time for normal menstrual cycles to return. Research suggests that lactation or breastfeeding delays the return of ovulation and menstrual cycles because it triggers hormones that suppress fertility (der Wijden, 2015). 

So, if you’re breastfeeding, your period may not return for 3–6 months after delivery. 

But it’s important to note that while breastfeeding can suppress hormones and make periods irregular, it is still possible to become pregnant while breastfeeding. If you don’t want to get pregnant during this time, it’s a good idea to use a backup form of birth control. 

10. Thyroid disease

Your thyroid is a gland in your neck that produces hormones and regulates many functions in the body. Both hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid) can cause disruptions in your menstrual cycle (Jacobson, 2018). 

If your healthcare provider suspects a thyroid problem, they will likely test the amount of thyroid hormone in your blood. Other signs of a thyroid problem include:

• Irregular heartbeat

• Appetite changes

• Weight changes

• Fatigue

• Trouble sleeping

• Hair changes

• Anxiety or nervousness

Intense stress can lead to hormonal disruptions that interrupt normal ovulation and menstrual cycles. 

When we are stressed, parts of the brain called the hypothalamus and pituitary gland are affected. Some portions become overactive, producing excess cortisol and suppressing gonadotropin-releasing hormone (GnRH) (Fourman, 2015). 

GnRH is the hormone responsible for releasing follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates the growth of follicles (eggs) in the ovaries and controls menstrual cycles. LH helps control menstrual cycles and triggers the release of the egg from the ovary. 

So when you’re stressed and GnRH is suppressed, it can be normal to miss a period. 

If you’re experiencing chronic high-stress levels and miss multiple periods, it may be best to schedule a visit with your healthcare provider or a mental health professional to help manage stress levels.

When you start a new contraceptive method, it can be alarming if you miss a period. Many people love hormonal contraceptive methods because of the potential to have lighter or fewer periods. 

If you’re taking the birth control pill, it’ll likely make your period more regular because of the three weeks taking the pill followed by one week off or of placebo pills. With an intrauterine device (IUD), shot, implant, or ring, your periods may only happen every three months or even stop completely. 

As you can see, not all missed periods are caused by pregnancy. It’s possible your missed period could be caused by hormonal imbalances, lifestyle factors, or health problems. 

But, if you’re sexually active and there is a chance you could be pregnant, it’s best to take a home pregnancy test just to be sure. If you are pregnant, you’ll want to know early so you can get prenatal care or make any decisions with your healthcare provider about how to proceed. If you decide to maintain your pregnancy, you’ll also want to change any habits that may be harmful to the baby, like drinking alcohol or smoking, as early in the pregnancy as possible.

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

January 19, 2022

Written by

Ashley Braun, RD, MPH

Fact checked by

Steve Silvestro, MD

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About the medical reviewer

Steve Silvestro, MD, Ro

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.