How common is intermenstrual bleeding?

Intermenstrual bleeding (IMB) – also called spotting, abnormal vaginal bleeding, or metrorrhagia – is bleeding that happens in between your periods; the average menstrual cycle is 28 days, although it can vary from 21 to 35 days. IMB should not be confused with irregular periods, which is when the period comes infrequently or at unpredictable times: shorter than 21 days or longer than 35 days.


IMB is very common and most women will experience it at some point in their lives. It has many possible causes – some harmless, some serious. Many young women, for instance, have intermenstrual or irregular bleeding, which is quite normal, until their cycle regulates. Still, it’s important not to ignore this symptom – no matter what your age – so see your doctor for a diagnosis and treatment.


Potential causes of Intermenstrual bleeding IMB include:

1. Hormonal imbalance – The hormones, estrogen and progesterone, regulate your cycle, and can be affected by:

  • the beginning (puberty) or near the end of a woman’s reproductive years (menopause)
  • spotting with ovulation (as a result of hormonal changes)
  • starting or stopping birth control: the pill or mini-pill, contraceptive ring, intrauterine device (IUD), injectable contraceptives or implants
  • dysfunctional ovaries
  • thyroid gland problems
  • starting hormone replacement therapy (HRT) after menopause

2. Implantation bleeding.This is when the fertilised egg attaches to your uterus lining.

3. Pregnancy. You can experience IMB after a miscarriage, termination of pregnancy, or ectopic pregnancy.

4. Infections. These include sexually transmitted infections (STIs), like chlamydia and or gonorrhoea, as well as pelvic inflammatory disease.

5. Benign growths, such as a polyp, fibroid, or growth on the cervix, vulva or vagina.

6. Thickening of the endometrium (also called hyperplasia).

7. Polycystic ovary syndrome (PCOS).

8. EndometriosisIt occasionally causes spotting a few days before your period.

9. Medicines, such as blood thinners.

10. Trauma or injury to the skin or tissue of the vagina

For a detailed list of causes and treatments, read Living with Metrorrhagia (Intermenstrual Bleeding)


If intermenstrual bleeding is common, when should I see a doctor?

Given the list of possible causes, if it happens once or twice, you can wait to see if it settles. If you are experiencing any spotting, though, always track when you are spotting, and if you have any other symptoms.

However, go to your doctor if:

    • You have bleeding that happens several times a month.
    • You have bleeding that happens over several months.
    • You have very heavy bleeding.
    • The bleeding is accompanied by other symptoms such as pain, fever, dizziness, easy bruising, fatigue, unusual vaginal discharge, an unusual odour, vaginal irritation and discomfort, and vaginal mucus that contains blood or has an appearance similar to that of cottage cheese.
    • You are older than 45 years of age.
    • You have bleeding after sex (post-coital bleeding).
    • You suspect that you might be pregnant.
    • You have postmenopausal bleeding.

Treatment will depend on the underlying cause.



  1. Ellis, M.E. (2023). Vaginal Bleeding Between Periods. Healthline [Online]. Accessed on 11 April 2023.
    Available from:
  2. Sissons, C. (2020). What causes bleeding between periods?. Medical News Today [Online]. Accessed on 11 April 2023.
    Available from: 
  3. The Fertility Institute on New Orleans. (2020). 10 Causes of Mid-Cycle Spotting. The Fertility Institute [Online]. Accessed on 11 April 2023.
    Available from: cycle- spotting/#:~:text=Around%205%25%20of%20women%20experience,typically%20pink%20or%20light %20red.
  4.  Wehn, D. E. (2018). Bleeding Between Periods? How To Tell If It’s a Problem. Cleveland Clinic [Online]. Accessed on 6 April 2023.
    Available from: about-spotting-between- periods/#:~:text=Many%20young%20women%20have%20irregular,your%20doctor%20for%20an%20 evaluation. 
  5. Western Sydney Local Health District. (2017).Fact Sheet Intermenstrual bleeding [IMB] WSP-566. Women’s & Newborn Health [Online] Accessed on 6 April 2023.
    Available from: bleeding%20FINAL%20May%202017.pdf.aspx 

These articles are for information purposes only. It cannot replace the diagnosis of a healthcare provider. Pharma Dynamics gives no warranty as to the accuracy of the information contained in such articles and shall not, under any circumstances, be liable for any consequences which may be suffered as a result of a user’s reliance thereon.

The information the reader is about to be referred to may not comply with the South Africa regulatory requirements. Information relevant to the South African environment is available from the Company and in the Professional Information/Patient Information Leaflet/Instructions for Use approved by the Regulatory Authority.

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