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What are Causes of Irregular Menstruation?

Medically reviewed by Mary Rani Cadiz, MD · Obstetrics and Gynecology

Written by Mayvilyn Cabigao · Updated Jun 10, 2021

    What are Causes of Irregular Menstruation?

    Menstruation or period naturally occurs once a girl reaches a certain age, normally around 12. The average menstrual cycle is 28 days +/- 7 days and  varies from women to women. On the other hand, some women are experiencing irregularities with their period. The causes of irregular menstruation range from hormonal changes, health conditions, and a lot more. Let us find out what they are.

    What is irregular menstruation?

    Should pregnancy not take place, having your period is your body’s natural way of shedding the thickened lining of the uterus due to hormonal changes. 

    A woman has irregular periods if her menstrual cycles have been inconsistent for the past 6 months. If your menstrual cycle seems to start too soon, too late, or too random, then you might have an irregular menstruation.

    Irregular menstruation is usually shorter than 21 days and longer than 38 days. Irregular menstruation is common in girls who just got their first period and women who are undergoing perimenopause.

    What causes irregular menstruation?

    The causes of irregular menstruation range from moderate to severe.

    Irregular menstruation causes include:


    When you are stressed, your body releases a stress hormone known as cortisol that can affect the levels of other hormones such as estrogen and progesterone.

    The changes in your hormones cause abnormalities in your menstrual cycle, such as the color of your menstrual blood, the amount of blood you eliminate, and the consistency of your bleeding patterns.


    Women who are going through perimenopause can experience a sudden change in their menstrual cycle since their estrogen and progesterone hormones become erratic.

    If a woman had a normal menstrual cycle before perimenopause, then the changes will be more noticeable.

    Why Does the Menstrual Cycle Stop at Menopause?


    After giving birth, your menstrual cycle will not go back to normal for a time . The irregular period in postpartum is totally normal and is a part of your body adjusting back to its pre-pregnancy state.


    If you are currently breastfeeding, you might notice that your period is still not going back to normal or is completely absent. This happens due to a hormone that makes milk which is known as prolactin.

    Prolactin hinders your body from ovulating as well as stops or changes your menstrual cycle. You don’t need to worry as your period will be more consistent after you stop breastfeeding.

    Hormonal birth control

    A hormonal birth control’s function is to stop ovulation, so pregnancy cannot happen. However, this type of birth control might mess up your menstrual cycle if taken erratically (at varying times per day), especially if you have missed some doses.

    Some women might experience some changes in the volume of their menstrual blood, and some have inconsistencies with their bleeding patterns.

    Polycystic ovarian syndrome (PCOS)

    One of the main causes of irregular menstruation in women is PCOS.

    PCOS is a condition that results from hormonal imbalance, which causes the eggs in the ovaries to not mature. The disruption in normal estrogen and progesterone levels result to anovulation.

    Polycystic Ovary Syndrome (PCOS): All You Need To Know

    Primary Ovarian Insufficiency (POI)

    This is a condition seen in women less than 40 years old whose ovarian function ceases. They have early transition to menopause.Women who suffer from this condition might not get their period for years and might occasionally have it randomly.

    Pelvic inflammatory disease (PID)

    Irregular menstruation can be a symptom of PID— a bacterial infection in a woman’s reproductive system that commonly comes from sexually transmitted diseases.

    Women can also get PID through childbirth, and other procedures done in the reproductive system.


    A woman who suffers from endometriosis often feels excruciating period pains.

    This disorder occurs as a result of endometrial tissue growing outside of the uterus. Endometriosis may cause shorter interval between menstrual cycles and abnormally excessive bleeding.

    Thyroid disease

    High and low levels of thyroid hormones can affect a woman’s menstrual cycle. The levels of your thyroid hormones can make your menstrual flow light, heavy, and inconsistent.

    Thyroid disease can make your menstrual cycle stop for months or even years and might give women difficulty in bearing a child.

    Asherman’s syndrome

    This uterine condition happens when scar tissues form inside the uterus or cervix. This usually happens with the history of instrumentation such as curettage.  Asherman’s syndrome causes infrequent menstruation that can sometimes be painful.

    Eating disorders

    Irregular periods can be an indication that a woman is experiencing an eating disorder (usually anorexia nervosa).

    However, eating disorders such as bulimia nervosa and binge eating disorder can lead to missed periods.

    Untreated diabetes

    When diabetes is left uncontrolled, it can cause an irregular menstrual cycle and heavy menstrual flow. But, your period can possibly go back to normal once your diabetes is under control.


    If a woman is obese, she is more prone to losing or having an irregular period.

    When you are overweight, your body makes more estrogen that helps regulate the reproductive system of women. But, high levels of estrogen often cause changes in your menstrual cycle.

    Certain medications

    Anti-epileptics and antipsychotic drugs can cause inconsistencies in a woman’s period.

    When to see your doctor

    If you have had a normal menstrual cycle since the first time you got your period, but it suddenly became irregular, then it is best to immediately consult an OB-Gyne.

    Checking with your doctor can help you determine what are the possible causes of irregular menstruation that you are currently experiencing.

    Doing this will help you and your doctor find the best interventions that can address your situation.

    Key takeaways

    The causes of irregular menstruation can vary for each woman. Thus, self-diagnosis is not advisable. If you have found the culprit of your menstrual irregularities, then it will be easier for you to prevent it from persisting.

    Once your doctor has given you the treatments and medications you need to take, make sure to commit to it so you can reap its benefits.

    Learn more about Women’s Health Issues, here


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Medically reviewed by

    Mary Rani Cadiz, MD

    Obstetrics and Gynecology

    Written by Mayvilyn Cabigao · Updated Jun 10, 2021

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