Why Do Menstrual Irregularities Occur? 14 Possible Causes

Your menstrual cycle is counted from the first day of your last period to the start of the next. It may be considered irregular if it lasts longer than 38 days or its timing varies.

Irregular periods can have causes other than hormonal imbalances and must be assessed by a doctor. Let us examine possible causes and associated complaints.

1. Pregnancy

You may overlook a pregnancy. Spotting may also prevent you from noticing it.

Other early pregnancy signs may include:

• Morning sickness
• Nausea
• Sensitivity to smells
• Breast tingling or tenderness
• Unexplained fatigue

If you are sexually active and miss a period or notice a change, you can take a home pregnancy test or see your doctor about possible pregnancy.

If you are pregnant and have sharp pelvic or abdominal pain lasting more than a few minutes, contact your doctor immediately to rule out ectopic pregnancy or miscarriage.

2. Hormonal Birth Control Methods

Hormonal birth control pills and hormonal intrauterine devices can cause irregular bleeding.

Birth control pills may cause spotting between periods and lighter periods.

- Related topic: Birth Control Pills – Oral Contraceptives and CANCER RISK

3. Breastfeeding

Prolactin is responsible for breast milk production. It suppresses other reproductive hormones, causing very light bleeding or no bleeding.

Regular periods are expected to return shortly after breastfeeding stops.

4. Perimenopause

Perimenopause is the transition before menopause. It generally begins in the late 40s but may start earlier.

Starting with period changes, symptoms may continue between 4 and 8 years. Fluctuating estrogen during this time may make periods longer or shorter.

Other signs and symptoms (complaints) of perimenopause include:

• Hot flashes
• Night sweats
• Mood changes
• Difficulty sleeping
• Vaginal dryness

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5. Polycystic Ovary Syndrome (PCOS)

Irregular menstrual bleeding is the most common sign of PCOS. With PCOS, after skipping a period, you may have heavier bleeding when your next period occurs.

PCOS may also cause:

• Difficulty becoming pregnant
• Unwanted facial and body hair
• Hair loss
• Weight gain or obesity

- Related topic: What Is Polycystic Ovary Syndrome and How Is It Treated? (in Detail)

6. Thyroid Problems

An underactive thyroid may cause longer, heavier bleeding.

A study in 2015 found thyroid disorders in 44 percent of participants with menstrual irregularities.

Hypothyroidism, or an underactive thyroid, can cause longer, heavier bleeding and increased cramps. Fatigue, cold sensitivity and weight gain may also occur.

You may also experience:

• Sudden weight loss
• Anxiety and irritability
• Heart palpitations
• Neck swelling is another common sign of thyroid disorders.

- Related topic: What Is Iodine Deficiency? Symptoms, Treatment and Its Relationship With Breast Cancer

7. Uterine Fibroids

Fibroids are benign muscle tumors developing in the uterine wall. Most are noncancerous and range from an apple seed to a grapefruit in size. They can make periods very painful and bleeding heavy enough to cause anemia. You may also experience:

• Pelvic (groin) pain or pressure
• Lower back pain
• Leg pain
• Pain during intercourse

Most fibroids need no treatment, and iron supplements may be used if anemia develops.

8. Endometriosis

Of every 10 women of reproductive age, endometriosis affects 1. It is a condition in which tissue normally belonging to the uterus grows outside it.

Endometriosis can cause severe pain, heavy and prolonged bleeding, and bleeding between periods.

Other symptoms may include:

• Abdominal pain
• Painful bowel movements
• Pain during and after intercourse
• Infertility

There is no treatment preventing endometriosis. Once it develops, if it causes signs and complaints, medication, hormone treatment or surgery can manage it.

9. Being Overweight

Obesity causes menstrual irregularity. Research shows excess weight changes hormone and insulin levels, which may affect the menstrual cycle.

Rapid weight gain can also cause irregular periods.

10. Excessive Weight Loss and Eating Disorders

Excessive or rapid weight loss may stop menstrual bleeding. Inadequate calorie intake can prevent production of the hormones needed for ovulation.

Below 18.5, a body mass indexmeans you are underweight. Alongside stopped periods, you may experience fatigue, headache and hair loss.

11. Excessive Exercise

Intense or excessive exercise has been shown to interfere with the hormones responsible for menstruation.

Female athletes and women doing intense training or activities such as ballet may experience missed or absent periods (amenorrhea).

Reworking your training and increasing calorie intake may help your periods return.

12. Stress

Research suggests stress may alter the menstrual cycle by interfering with hormones. Periods should normalize when stress decreases.

13. Medications

Some drugs may affect the menstrual cycle:

• Hormone-suppressing treatments
• Hormone replacement treatments
• Blood thinners
• Thyroid medications
• Epilepsy medications
• Antidepressants
• Chemotherapy drugs
• Aspirin and ibuprofen

Consult your doctor about changing medications.

- Related topic: What Is Hormone Replacement Therapy? Which Women Should Use It and When?

14. Cervical and Endometrial (Uterine) Cancers

Cervical and endometrial cancers may cause menstrual cycle changes and bleeding between periods. Bleeding during or after intercourse and unusual discharge are other signs and symptoms. However, these cancers are not the first conditions to consider with menstrual irregularity. Talk to your doctor if you are concerned. 

Related Topic:

- Treatment of Gynecological Cancers – Innovations in 2017 and 2018