Why Is My Period Irregular? Causes, Concerns, and When to See a Doctor

Your period is late again. Or maybe it came too early. Or it skipped a month entirely. If this sounds familiar, you're not alone, about 14 to 25% of women experience irregular menstrual cycles at some point.

But "irregular" means different things to different people, so let's start with the basics.

What counts as an irregular period?

A "normal" menstrual cycle ranges from 21 to 35 days, with an average of about 29 days. Your period itself (the bleeding phase) usually lasts 3 to 7 days.

Your period is considered irregular if:

• Your cycles are consistently shorter than 21 days or longer than 35 days
• You miss three or more periods in a row
• Your flow is much heavier or much lighter than usual
• Your periods last longer than 7 days
• The gap between periods varies widely from month to month

Some irregularity is completely normal during puberty and perimenopause (the years leading up to menopause, typically in your 40s), when hormone levels fluctuate naturally.

Common causes of irregular periods

1. Stress

Under significant stress, your body produces more cortisol (the "stress hormone"), which can interfere with the hormones that control your menstrual cycle, delaying or even stopping your period temporarily.

2. PCOS (Polycystic Ovary Syndrome)

One of the most common causes. It involves a hormonal imbalance where your ovaries produce too many androgens, which can prevent regular ovulation. If you're also experiencing acne, weight gain, or excess body hair, PCOS may be worth investigating.

3. Thyroid disorders

Your thyroid produces hormones that affect nearly every system in your body. Hypothyroidism (underactive) can cause heavier, more frequent periods; hyperthyroidism (overactive) can cause lighter, less frequent periods. A simple blood test can check your levels.

4. Weight changes

Both significant weight loss and weight gain can disrupt your periods. Being underweight can lower estrogen and cause missed periods; being overweight can lead to excess estrogen that throws off your cycle.

5. Excessive exercise

Intense training can suppress reproductive hormones, leading to missed or irregular periods. This is sometimes called the "female athlete triad" when combined with low energy intake and bone loss.

6. Birth control

Hormonal contraceptives can affect your cycle. When you start or stop them, it can take a few months for your cycle to regulate.

7. Fibroids or polyps

Uterine fibroids (non-cancerous growths in the womb) and polyps (small growths on the uterine lining) can cause heavy or prolonged periods.

8. Pelvic Inflammatory Disease (PID)

A bacterial infection of the reproductive organs, usually from untreated STIs like chlamydia or gonorrhea. It can cause irregular bleeding, pelvic pain, and unusual discharge.

9. Perimenopause

In your 40s (sometimes earlier), estrogen begins to fluctuate as you approach menopause, naturally leading to irregular periods.

10. Other medical conditions

Diabetes, celiac disease, and certain medications (including some antidepressants and blood thinners) can also affect your cycle.

When should you see a doctor?

Make an appointment if:

• Your periods have stopped for 3 months or more and you're not pregnant
• Your cycles are consistently shorter than 21 days or longer than 35 days
• You're bleeding between periods
• Your periods have become much heavier than usual (soaking through a pad or tampon every hour)
• You experience severe pain during your period
• You've gone through puberty and your periods haven't started by age 15
• You suspect PCOS, thyroid issues, or another underlying condition

What to expect at the doctor

Your provider will likely ask about your menstrual history, do a physical exam (including a pelvic exam), order blood tests to check hormone levels, blood sugar, and blood count, and possibly order an ultrasound to check for fibroids, polyps, or ovarian cysts.

Treatment options

Treatment depends entirely on the underlying cause:

• PCOS, lifestyle changes, hormonal birth control, or medications like metformin
• Thyroid issues, thyroid medication to normalise hormone levels
• Fibroids or polyps, medication or surgical procedures
• Stress-related, mindfulness, therapy, or lifestyle adjustments
• Weight-related, working with a provider or dietitian to reach a healthy weight
• PID, antibiotics to treat the infection

A note for African women

In many parts of West and East Africa, cultural norms mean period problems are often not discussed openly, and pain is sometimes dismissed as something women just have to endure.

This is not true. Severe menstrual pain, very heavy bleeding, or missed periods are your body's way of telling you something needs attention. You deserve proper medical care, and you should feel empowered to seek it.

The bottom line

Irregular periods are common, but they're also worth paying attention to. They can be a signal of an underlying condition that's treatable. Track your cycle, note your symptoms, and don't hesitate to talk to a healthcare professional if something feels off.