What is Menstrual Irregularity and What Causes It?

A healthy woman typically experiences menstrual bleeding every 24–38 days. Under the influence of hormones that regulate the female reproductive system, the endometrial lining of the uterus thickens and becomes rich in blood vessels, preparing for a possible pregnancy. At the end of the cycle, this lining sheds, resulting in menstruation [1].

A normal menstrual cycle ranges between 24–38 days, lasts 2–7 days, and involves a blood loss of approximately 5–80 mL. Any deviation in frequency, duration, regularity, or volume of bleeding is defined as abnormal uterine bleeding (AUB) [1]. Studies indicate that about one-third of women of reproductive age experience menstrual irregularities at some point in their lives [1].

What Causes Menstrual Irregularities?

The International Federation of Gynecology and Obstetrics (FIGO) classifies the causes of abnormal uterine bleeding into two main groups using the PALM-COEIN system [2]:

Structural causes (PALM): Polyps, adenomyosis, fibroids (leiomyomas), malignancy, and endometrial hyperplasia

Non-structural causes (COEIN): Coagulopathies, ovulatory dysfunction, endometrial disorders, and iatrogenic (medication-related) causes

In addition, the following risk factors may lead to menstrual irregularities:

Cysts and fibroids
Endometrial or cervical polyps
Certain hormonal medications
Lack of ovulation or ovulatory disorders
Infections
Estrogen-related conditions
Thyroid hormone deficiency
Diabetes and chronic diseases
Intense exercise and unbalanced nutrition
Rapid weight gain or loss
Stress

For evaluation of menstrual irregularities and hormonal balance, you can visit our Gynecology page.

Types of Menstrual Irregularities

Menstrual irregularities are classified based on their cause and bleeding pattern [1, 2]:

Hypermenorrhea: Excessive bleeding (>80 mL)
Hypomenorrhea: Reduced bleeding
Menorrhagia: Prolonged or heavy menstrual bleeding
Menometrorrhagia: Heavy and irregular bleeding
Metrorrhagia: Bleeding between periods
Oligomenorrhea: Cycle longer than 35 days
Polymenorrhea: Cycle shorter than 21 days
Amenorrhea: Absence of menstruation

What Are the Symptoms?

Very heavy bleeding (needing to change pads/tampons hourly)
Dizziness, nausea, vomiting
Persistent fatigue and weakness
Frequent or very infrequent periods
Menstruation lasting less than 2 days or more than 8 days
Severe pain and cramps
Cycle shorter than 21 days or longer than 35 days

Can Menstrual Irregularities Be Treated?

Menstrual irregularity is not a disease on its own; it is usually a symptom of an underlying condition. Therefore, treatment is based on identifying and addressing the root cause [1]. Treatment options include:

Hormonal causes: Hormone-regulating medications or hormone replacement therapy
Fibroids: Myomectomy or hysterectomy depending on age and fertility plans
Organic conditions: Hysteroscopic evaluation and removal of abnormal tissue
Lifestyle-related causes: Nutritional adjustments, stress management, and optimization of physical activity

Frequently Asked Questions (FAQ)

What is considered a normal menstrual cycle?

According to FIGO guidelines, a normal cycle occurs every 24–38 days, lasts 2–7 days, and involves 5–80 mL of blood loss.

Can stress cause menstrual irregularities?

Yes. Chronic stress can disrupt hormonal balance and ovulation.

Can menstrual irregularities cause infertility?

In some cases, yes—especially when related to ovulatory dysfunction or PCOS.

Are irregular periods normal during adolescence?

Mild irregularities in the first 1–2 years may be normal, but persistent issues should be evaluated.

When should I see a doctor?

You should consult a doctor in cases of very heavy bleeding, missed periods for several months, or severe pain.

References

Wouk, N. & Helton, M. (2019).
Munro, M. G., et al. (2023).

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