Why Are My Periods Irregular? 10 Common Causes Every Woman Should Know
Irregular periods are one of the most common reasons women consult a gynaecologist. If your periods are coming too early, too late, are unusually heavy or light, or have stopped altogether, it may be your body’s way of signalling an underlying health condition.
While occasional changes in the menstrual cycle are common and not always a cause for concern, persistent irregularities should not be ignored. Hormonal imbalances, thyroid disorders, polycystic ovary syndrome (PCOS), stress, weight changes, and several other conditions can affect the regularity of your menstrual cycle.
At Kavin Maternity & Fertility Clinic, Dr. Nivedha Arunachalam provides a comprehensive evaluation to identify the underlying cause of irregular periods and offers personalised treatment based on your symptoms, age, and reproductive goals.
This guide explains the common causes of irregular periods, how they are diagnosed, and when you should seek medical advice.
What Is a Normal Menstrual Cycle?
A normal menstrual cycle is counted from the first day of one period to the first day of the next and usually lasts 21 to 35 days. Menstrual bleeding typically lasts 2 to 7 days, and slight variations from month to month are common.
You should consider consulting a gynaecologist if:
- Your periods occur more frequently than every 21 days or less frequently than every 35 days
- Your bleeding lasts longer than 7 days
- You experience unusually heavy bleeding
- Your periods stop for three months or more when you are not pregnant
- You have bleeding between periods or after sexual intercourse
Irregular periods are often a symptom rather than a condition by themselves. Identifying the underlying cause is the first step towards effective treatment.
Cause 1 – Polycystic Ovary Syndrome (PCOS)
PCOS is one of the most common hormonal disorders affecting women of reproductive age and a frequent cause of irregular periods.
In PCOS, hormonal imbalance interferes with normal ovulation. Without regular ovulation, the lining of the uterus is not shed predictably, resulting in delayed, infrequent, or absent menstrual periods.
In addition to irregular periods, women with PCOS may experience:
- Acne
- Excess facial or body hair
- Weight gain or difficulty losing weight
- Scalp hair thinning
- Difficulty conceiving
Diagnosis is based on a combination of your medical history, symptoms, physical examination, blood tests, and ultrasound findings. Not every woman with PCOS has all these features, and treatment is tailored to her individual concerns.
Management may include lifestyle modification, weight management where appropriate, medications to regulate menstrual cycles, or fertility treatment for women planning pregnancy.
Early diagnosis and appropriate treatment not only help regulate periods but also reduce the long-term risks associated with PCOS, such as diabetes and endometrial problems.
Cause 2 – Thyroid Disorders
The thyroid gland plays an important role in regulating many body functions, including the menstrual cycle. Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) can lead to irregular periods.
Women with hypothyroidism may experience:
- Heavy or prolonged periods
- Fatigue
- Weight gain
- Dry skin
- Constipation
- Feeling unusually cold
Women with hyperthyroidism may notice:
- Light or infrequent periods
- Weight loss
- Palpitations
- Anxiety
- Tremors
- Heat intolerance
If a thyroid disorder is suspected based on your symptoms or examination, your doctor may recommend thyroid function tests. Treating the underlying thyroid condition often helps restore a normal menstrual cycle.
Cause 3 – Stress
Emotional and physical stress can temporarily affect the hormones responsible for ovulation, making stress one of the common causes of delayed or missed periods.
Work pressure, examinations, relationship problems, poor sleep, major life events, or chronic illness can all influence the menstrual cycle.
When the body experiences significant stress, the brain may temporarily delay ovulation, causing periods to occur later than expected or, in some cases, stop altogether.
Managing stress through adequate sleep, regular exercise, relaxation techniques, mindfulness, or professional counselling often helps restore normal menstrual cycles. However, if your periods remain irregular for several months, it is important to seek medical evaluation to rule out other underlying causes.
Cause 4 – Sudden Weight Changes
Maintaining a healthy body weight plays an important role in regulating hormones and ensuring regular ovulation. Both significant weight loss and weight gain can disrupt the menstrual cycle.
Rapid weight loss due to crash dieting, excessive exercise, eating disorders, or severe illness may reduce the production of reproductive hormones, causing delayed or absent periods. This condition is known as functional hypothalamic amenorrhoea.
Similarly, obesity and rapid weight gain can alter hormone levels and increase insulin resistance, making ovulation irregular. This is particularly common in women with PCOS.
Maintaining a healthy weight through balanced nutrition, regular physical activity, and sustainable lifestyle changes can help restore normal menstrual cycles. If your periods become irregular after a significant change in weight, consult your gynaecologist for a proper evaluation.
Cause 5 – Perimenopause
Perimenopause is the natural transition leading up to menopause and usually begins during the 40s, although the age varies from woman to woman.
During this stage, hormone levels fluctuate, making ovulation less predictable. As a result, menstrual cycles may become irregular.
You may notice:
- Periods occurring closer together or farther apart
- Heavier or lighter bleeding
- Skipped periods
- Changes in the duration of menstrual flow
Many women also experience symptoms such as:
- Hot flushes
- Night sweats
- Mood changes
- Difficulty sleeping
- Vaginal dryness
- Reduced libido
Menopause is confirmed after 12 consecutive months without a menstrual period.
Although irregular bleeding is common during perimenopause, any bleeding after menopause should always be evaluated by a gynaecologist, as it may indicate an underlying condition that requires investigation.
Cause 6 – Uterine Fibroids and Endometrial Polyps
Fibroids and endometrial polyps are common, non-cancerous conditions that can affect the uterus and cause changes in menstrual bleeding.
Uterine fibroids are benign growths arising from the muscle of the uterus. Depending on their size and location, they may cause:
- Heavy or prolonged periods
- Pelvic pressure or pain
- Frequent urination
- Constipation
- Difficulty conceiving in some women
Endometrial polyps are growths arising from the lining of the uterus. They commonly cause:
- Irregular menstrual bleeding
- Bleeding between periods
- Heavy menstrual flow
- Spotting after intercourse
- Bleeding after menopause
A pelvic ultrasound is usually the first investigation. In selected cases, your doctor may recommend saline infusion sonography or hysteroscopy to examine the uterine cavity in greater detail.
Treatment depends on the size of the fibroid or polyp, your symptoms, age, and future pregnancy plans. Options range from observation and medication to minimally invasive surgical procedures when required.
Cause 7 – Endometriosis
Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus, commonly affecting the ovaries, fallopian tubes, pelvic lining, bowel, or bladder.
This tissue responds to hormonal changes during each menstrual cycle, leading to inflammation, scarring, and chronic pelvic pain.
Common symptoms include:
- Painful periods that interfere with daily activities
- Chronic pelvic pain
- Pain during or after sexual intercourse
- Pain during bowel movements or urination during menstruation
- Difficulty conceiving
It is important to remember that the severity of symptoms does not always reflect the severity of the disease. Some women have extensive endometriosis with minimal symptoms, while others experience severe pain despite mild disease.
Diagnosis begins with a detailed medical history, pelvic examination, and pelvic ultrasound performed by an experienced clinician. MRI may be recommended in selected women, particularly when deep endometriosis is suspected.
Laparoscopy is no longer required to diagnose every case of endometriosis. It is generally recommended when the diagnosis remains uncertain, symptoms do not improve with medical treatment, or surgery is planned.
Treatment is individualised and may include pain-relieving medications, hormonal therapy, laparoscopic surgery, or fertility treatment depending on your symptoms and reproductive goals.
Cause 8 – Hormonal Contraception
Hormonal contraceptives, including birth control pills, hormonal intrauterine devices (IUDs), implants, and injectable contraceptives, can temporarily change your menstrual bleeding pattern. These changes are usually expected and often improve as your body adjusts.
During the first 3 to 6 months after starting hormonal contraception, you may experience:
- Irregular spotting or breakthrough bleeding
- Lighter or shorter periods
- Less frequent periods
- Occasionally, no periods at all, depending on the contraceptive method
Similarly, after stopping hormonal contraception, it may take a few weeks to a few months for regular ovulation and menstrual cycles to return. If your periods do not resume within three months, or if you continue to have irregular cycles, consult your gynaecologist to rule out other underlying conditions.
Cause 9 – Premature Ovarian Insufficiency (POI)
Premature Ovarian Insufficiency (POI) occurs when the ovaries lose their normal function before the age of 40 years. Although less common, it is an important cause of irregular or absent periods because it can affect fertility as well as long-term bone and heart health.
Women with POI may experience:
- Irregular or absent periods
- Hot flushes
- Night sweats
- Vaginal dryness
- Mood changes
- Difficulty conceiving
POI may occur due to genetic conditions, autoimmune disorders, previous ovarian surgery, chemotherapy or radiotherapy, although in many women no specific cause is identified.
Diagnosis is based primarily on your symptoms and repeated blood tests showing elevated Follicle Stimulating Hormone (FSH) levels. Additional investigations may be recommended to determine the underlying cause. While AMH provides information about ovarian reserve, it is not used alone to diagnose POI.
Treatment may include hormone replacement therapy (when appropriate), lifestyle measures to support bone health, and fertility counselling based on your reproductive goals.
Cause 10 – Hyperprolactinaemia
Prolactin is a hormone produced by the pituitary gland that stimulates breast milk production after childbirth. When prolactin levels become elevated in women who are not pregnant or breastfeeding, ovulation may be affected, leading to irregular or absent periods.
Symptoms may include:
- Irregular or missed periods
- Difficulty conceiving
- Milky discharge from the breasts (galactorrhoea)
- Occasionally headaches or visual disturbances
Common causes include certain medications, thyroid disorders, benign pituitary tumours (prolactinomas), and, less commonly, other medical conditions.
Diagnosis usually involves blood tests to measure prolactin levels. Depending on the results, your doctor may recommend additional investigations, such as thyroid function tests or MRI of the pituitary gland.
Most women respond well to medical treatment, and normal menstrual cycles often return once prolactin levels are controlled.
When Should You See a Gynaecologist?
Occasional changes in your menstrual cycle are common, but persistent irregular periods should not be ignored.
Consult a gynaecologist if:
- Your periods occur more frequently than every 21 days or less frequently than every 35 days
- Your periods stop for more than three months and you are not pregnant
- Your bleeding lasts longer than seven days
- You experience very heavy menstrual bleeding
- You have bleeding between periods or after sexual intercourse
- Your periods are associated with severe pelvic pain
- You are trying to conceive and have irregular menstrual cycles
- You develop symptoms suggestive of early menopause before the age of 40
Early evaluation can help identify the underlying cause and prevent potential long-term complications.
How Are Irregular Periods Diagnosed?
At Kavin Maternity & Fertility Clinic, every woman undergoes an individualised evaluation based on her symptoms, age, and reproductive goals.
Your assessment may include:
- A detailed menstrual and medical history
- Physical and pelvic examination, where appropriate
- Pregnancy test, if indicated
- Selected blood tests, including thyroid function, prolactin, or reproductive hormones
- Pelvic ultrasound to evaluate the uterus and ovaries
Additional investigations such as hysteroscopy, saline infusion sonography, MRI, or laparoscopy are recommended only when clinically indicated.
Treatment for Irregular Periods
Treatment depends on the underlying cause and is tailored to each individual.
Management may include:
- Lifestyle modifications, including weight management and regular exercise
- Hormonal medications to regulate menstrual cycles
- Treatment for thyroid disorders or elevated prolactin levels
- Medical or surgical management of fibroids, polyps, or endometriosis
- Fertility treatment for women planning pregnancy
The goal is not just to regulate periods but also to improve overall reproductive and long-term health.
Frequently Asked Questions
Is it normal to have irregular periods as a teenager?
Yes. Irregular cycles are common during the first 2–3 years after menstruation begins, as ovulation may not occur regularly. However, persistent irregularity or heavy bleeding should be evaluated.
Can irregular periods affect fertility?
Yes. Irregular periods often indicate irregular ovulation, which may make conception more difficult. Fortunately, many underlying causes are treatable.
Can stress affect my menstrual cycle?
Yes. Significant physical or emotional stress can temporarily delay or stop ovulation, resulting in missed or delayed periods.
Are irregular periods always a sign of a serious problem?
Not necessarily. Occasional irregularity is common, but persistent changes should be evaluated to identify and treat any underlying condition.
Why Choose Kavin Maternity & Fertility Clinic?
At Kavin Maternity & Fertility Clinic, we provide compassionate, evidence-based care tailored to every stage of a woman’s life. Dr. Nivedha Arunachalam offers a comprehensive evaluation to identify the cause of irregular periods and develops personalised treatment plans based on your symptoms, health, and future fertility goals.
Whether you need reassurance, medical treatment, or fertility support, our aim is to help you achieve better reproductive health through clear guidance and ethical, patient-centred care.
Disclaimer
This article is intended for educational purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment. Every woman’s health concerns are unique, and investigations and treatment are individualised based on medical history, clinical findings, and reproductive goals. Please consult a qualified gynaecologist for personalised medical advice.
