Menstruation | What’s Normal, and What’s Not

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2 min read

Healthy Matters

While perhaps not the highlight of your month, the menstrual cycle rolls around twelve-ish times a year. Every month the uterus prepares a new lining in preparation for a potential pregnancy. When a woman doesn’t find herself pregnant, the lining sheds, causing bleeding.


In collaboration with Dr. Selina Pang 彭敏華醫生, we explain what normal periods looks like and what some common abnormalities may mean.

A normal menstrual cycle lasts from 23-35 days, measured from the first day of your period to the first day of your next period. Looking at 2 consecutive cycles, anything less than 21 days is considered "advanced menstruation" or more than 35 days is considered “delayed menstruation”.


Length of your bleeding

Bleeding usually lasts for 5 days. The normal range is 2-7 days. Bleeding for more than 8 days could be a sign of an underlying condition.

Irregular cycles

Each body is different so it’s the regularity that’s important within this range. That’s your normal. Of course, many women will experience some variation in the length between period in their lives. If the length between your normal period cycle suddenly changes, it may be due to stress/anxiety, medication, puberty or menopause, emergency contraception or hormonal birth control. If you find your period timing is becoming more “irregular” than “regular”, it’s worth checking in with your doctor.


Some pain and discomfort right before and during the first few days of your period is normal but some women experience dysmenorrhea, a higher-than-normal amount of pain accompanying their bleeding. If at-home remedies like over-the-counter pain relief and hot water bottles aren’t helping the pain subside, mention this to your doctor.


Heavy menstrual bleeding (HMB) is defined as losing more than 80mL per cycle. For those of us not using a measuring cup, the UK’s National Institute for Health and Care Excellence (NICE) defines HMB as enough to ‘disrupt your life’ and should be present for the majority of your previous six periods. If this sounds like you, you should visit your gynecologist.


The color of your period blood likely varies throughout your cycle. It can range from bright red to brown to black – anything in this spectrum is normal. Like a fresh cut’s bright red blood to a scab’s brown hue, the variation is due to the age of the blood. Brown and dark red indicate older blood that has been sitting in your uterus; red is newer blood. If you have gray discharge, this could be a sign of an infection and requires a visit to your gynecologist.

Period clots spotting

Spotting is bleeding outside of your normal period. Some spotting in between periods, especially during ovulation, is normal. If your spotting is not during ovulation, is a strange color, or is due to an abdominal injury, it could be a sign of something to talk to your doctor about.

So, what should you worry about?

You should talk to your doctor if you have any of these signs. 

  • Heavy menstrual bleeding
  • Grey discharge
  • Clots larger than a HK$2 coin
  • The timing between periods changes suddenly
  • Your cycle is less than 21 days or more than 35 days for 2 consecutive cycles
  • Bleeding for more than 8 days
  • Excessive pain
  • Abnormal spotting

Healthy Matters’ tip on tracking your cycle

Tracking your menstrual cycle can give you and your doctor some really helpful insight into what might be going on. One of the most popular and scientifically reliable apps Healthy Matters has identified is Clue, a free period tracker for iPhone and Android. The app has over 2.5 million users from 180 different countries and has partnered with universities such as Stanford, Columbia University, the University of Washington, and the University of Oxford to advance female health research.

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This article was independently written by Healthy Matters and is not sponsored. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.

Dr. Pang Man Wah Selina
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