For many people with regular menstrual cycles, a late or missed period can be stressful and confusing. While pregnancy is often the first concern, there are many other reasons your period may not arrive on time. Changes in lifestyle, medical conditions, and hormonal fluctuations can all play a role.

This article covers eight possible causes of a delayed period and offers guidance on when it's time to talk to a healthcare provider.

1. Stress and Emotional Strain

Mental and emotional stress can significantly influence hormonal balance and impact the timing of your menstrual cycle. When the body is under high levels of stress, it can produce more cortisol, a hormone that can interfere with the normal production of estrogen and progesterone—the hormones that regulate your cycle.

Common symptoms associated with stress-induced menstrual changes include:

  • Missed or delayed periods

  • More painful menstrual cramps

  • Lighter or heavier bleeding than usual

Simple lifestyle changes such as getting adequate rest, managing anxiety, practicing mindfulness, and engaging in regular physical activity can support hormonal balance. If chronic stress is affecting your health, consider reaching out to a counselor or physician.

 

2. Perimenopause and Hormonal Shifts

The transition to menopause, known as perimenopause, typically begins in your 40s but can start earlier for some individuals. During this time, estrogen levels fluctuate unpredictably, and this can lead to:

  • Irregular or skipped periods

  • Changes in flow (heavier or lighter)

  • Hot flashes, sleep problems, or mood swings

Eventually, once you’ve gone 12 consecutive months without a period, menopause is considered complete. If you're over 40 and noticing changes in your cycle, it's worth discussing with your doctor to rule out other possible causes.

3. Sudden Weight Loss or Low Body Fat

Losing a significant amount of weight quickly, particularly through restrictive dieting or intense physical training, can disrupt the menstrual cycle. This is especially true if body fat drops below what’s needed to maintain reproductive hormone levels.

When estrogen levels fall too low, ovulation may stop, leading to missed periods—a condition known as hypothalamic amenorrhea.

Some common triggers include:

  • Eating disorders such as anorexia or bulimia

  • Extreme calorie restriction

  • Overtraining without proper nutrition

If you've recently lost weight and your period has stopped, it’s important to speak with a healthcare provider or registered dietitian.

4. Obesity and High Body Fat Percentage

Carrying excess weight can also impact menstrual health. Fat cells produce estrogen, and when there is an overproduction of this hormone, it can interfere with ovulation.

In some cases, delayed or irregular periods related to obesity may be linked to polycystic ovary syndrome (PCOS), a hormonal condition that affects how the ovaries function.

Obesity may also lead to:

  • Heavier menstrual bleeding

  • Extended menstrual cycles

  • Increased risk of endometrial hyperplasia

A medical evaluation that includes hormone testing and imaging (such as an ultrasound) can help identify underlying causes.

5. Birth Control Methods

Some types of hormonal contraception, including pills, patches, implants, and intrauterine devices (IUDs), can alter your menstrual cycle.

These contraceptives often work by:

  • Preventing ovulation

  • Thinning the uterine lining

  • Altering hormone levels

As a result, you may experience lighter periods or none at all, especially when using continuous or long-acting birth control methods. While usually not harmful, any unexpected changes should be discussed with a healthcare provider to ensure your method is still suitable.

6. Hormonal Imbalances and Thyroid Issues

Your menstrual cycle is tightly regulated by several hormones, including:

  • Prolactin

  • Thyroid hormones (T3, T4, TSH)

  • Estrogen and progesterone

An underactive or overactive thyroid can cause irregular or missed periods. Similarly, conditions that elevate prolactin levels may interfere with ovulation.

Symptoms that might indicate a hormonal disorder include:

  • Fatigue

  • Unexpected weight changes

  • Sensitivity to temperature

  • Irregular cycles or complete absence of menstruation

Blood tests can determine if a thyroid or endocrine disorder is contributing to the issue, and treatment often helps restore regular cycles.

7. Polycystic Ovary Syndrome (PCOS)

PCOS is one of the most common hormonal conditions in reproductive-age women. It is characterized by a range of symptoms, including:

  • Irregular or absent periods

  • Excess hair growth on the face or body

  • Acne or oily skin

  • Weight gain or difficulty losing weight

  • Ovarian cysts (often seen on ultrasound)

PCOS is associated with elevated levels of androgens (male hormones) and insulin resistance. If left unmanaged, it can impact fertility and increase the risk of conditions like type 2 diabetes and endometrial cancer.

Early diagnosis and lifestyle or medication-based management can greatly reduce complications.

8. Pregnancy

Even if you're using birth control, no method (except complete abstinence) is 100% effective. A late period could be the first sign of pregnancy.

Other early signs include:

  • Tender breasts

  • Mild cramping

  • Nausea or vomiting

  • Increased urination

  • Fatigue

A home pregnancy test can provide answers, but it’s best to follow up with a doctor for confirmation and early prenatal care if you test positive. If your test is negative but your period doesn’t return, it’s still a good idea to speak with a healthcare provider.

When to See a Doctor About a Late Period

While a single missed period might not be a cause for concern, there are situations when seeking medical advice is recommended:

  • You’ve missed more than two periods in a row

  • You suspect you might be pregnant

  • You’ve recently experienced significant weight loss or gain

  • You’re showing signs of PCOS or thyroid issues

  • You’ve entered your 40s and are noticing new changes in your cycle

Keeping a menstrual calendar—either on paper or using a mobile app—can help track patterns and provide useful information for your doctor.

Summary

A delayed or missed period can be unsettling, especially if it’s unexpected. While pregnancy is one of the most common reasons, many other factors—from stress and lifestyle changes to medical conditions like PCOS or thyroid imbalances—can also impact your cycle.

Tracking your periods, staying aware of your health, and discussing any unusual changes with a doctor can help ensure any underlying concerns are addressed promptly.