Why Is My Period Irregular? Causes, Concerns, and When to See a Doctor
- Asele Team
- Apr 14
- 4 min read
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 (for example, 25 days one cycle, then 45 days the next)
Keep in mind that some irregularity is completely normal during puberty (when periods first start) and perimenopause (the years leading up to menopause, typically in your 40s). During these transitions, hormone levels fluctuate naturally.
Common Causes of Irregular Periods
1. Stress
When you're under significant stress — whether emotional, physical, or psychological — your body produces more cortisol (the "stress hormone"). High cortisol can interfere with the hormones that control your menstrual cycle, delaying or even stopping your period temporarily.
2. PCOS (Polycystic Ovary Syndrome)
PCOS is one of the most common causes of irregular periods. It involves a hormonal imbalance where your ovaries produce too many androgens (male-type hormones), which can prevent regular ovulation (the release of an egg). If you're also experiencing acne, weight gain, or excess body hair, PCOS may be worth investigating.
(Read our full PCOS guide.)
3. Thyroid Disorders
Your thyroid (a small, butterfly-shaped gland in your neck) produces hormones that affect nearly every system in your body — including your menstrual cycle.
Hypothyroidism (underactive thyroid) can cause heavier, more frequent periods
Hyperthyroidism (overactive thyroid) can cause lighter, less frequent periods
A simple blood test can check your thyroid hormone levels.
4. Weight Changes
Both significant weight loss and weight gain can disrupt your periods. Being underweight can cause your body to stop producing enough estrogen, leading to missed periods. Being overweight can lead to excess estrogen production, which can also throw off your cycle.
5. Excessive Exercise
Intense physical training — common in athletes — can cause your body to 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 (pills, IUDs, implants, injections) can affect your cycle. Some cause lighter or absent periods. When you start or stop hormonal birth control, it can take a few months for your cycle to regulate. (See our contraception guide for details on each method.)
7. Fibroids or Polyps
Uterine fibroids (non-cancerous growths in the womb) and polyps (small growths on the lining of the uterus) can cause heavy or prolonged periods. (Learn more in our fibroids guide.)
8. Pelvic Inflammatory Disease (PID)
PID is a bacterial infection of the reproductive organs, usually caused by untreated sexually transmitted infections (STIs) like chlamydia or gonorrhea. It can cause irregular bleeding, pelvic pain, and unusual discharge. (Read about STI symptoms and prevention.)
9. Perimenopause
In your 40s (sometimes earlier), your estrogen levels begin to fluctuate as you approach menopause. This naturally leads to irregular periods — cycles may become shorter, longer, heavier, lighter, or more unpredictable. (See our post on perimenopause.)
10. Other Medical Conditions
Conditions like 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 periods 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 you might have PCOS, thyroid issues, or another underlying condition
What to Expect at the Doctor
Your healthcare provider will likely:
Ask about your menstrual history — When your last period was, how long your cycles typically are, how heavy your bleeding is
Do a physical exam — Including a pelvic exam
Order blood tests — To check hormone levels (estrogen, progesterone, thyroid hormones, prolactin), blood sugar, and blood count
Possibly order imaging — 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. (Details in our PCOS post.)
Thyroid issues — Thyroid medication to bring hormone levels back to normal
Fibroids or polyps — Medication or surgical procedures to remove them
Stress-related — Stress management techniques like mindfulness, therapy, or lifestyle adjustments
Weight-related — Working with a healthcare 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 that period problems are often not discussed openly. Pain during periods 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.
References
Cleveland Clinic. "Abnormal Menstruation (Periods)." clevelandclinic.org
Office on Women's Health. "Period Problems." womenshealth.gov
PMC. "The Impact of Irregular Menstruation on Health: A Review of the Literature." pmc.ncbi.nlm.nih.gov
Mount Sinai. "Menstrual Disorders." mountsinai.org
SusPads. "Period Health Complications in West Africa." suspads.com
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