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Period Pain

By Timothy Cocks Education for all 08 Dec 2017

We are very excited to welcome for the first time to NOIjam, Professor Sonia Grover (you can check her bio below), who has contributed the following piece.

Not so straight forward

I had been trying to think of a way of describing to a mother and her teenage daughter what actually happens when a period occurs and why it actually might hurt – even though this process is normal. The following is something along the lines of the discussion we had…


On the one hand menstruation seems pretty straight forward –  we know that there is a change in hormones and bleeding happens.

So, if the hormones change and the uterus bleeds, why don’t other parts of the body also bleed? Maybe it’s not so simple after all. Perhaps the answer is that the lining of the uterus is ‘special’. Again, that sounds correct and straight forward, and in some respects it is, except, why should the lining, which has been quietly growing and getting thicker over a four week time span since the last period, decide to start to bleed just because some hormones change?

A side trip to context

Now we are getting deeper into this amazing biology. But first it’s worth taking a little side trip to put some context around what is going on in your body every month [I might not use the following metaphor with everyone, but I was confident that this young woman would benefit from the perspective I feel this story can provide]. The lining of the uterus is about the equivalent of the skin covering a single finger. But where the skin covering a finger might be a few millimetres or so thick, the lining of the uterus grows up to 4-6mm in thickness before it is shed. Losing this much ‘skin’ every month is no small event in biological terms, and while it is completely normal and natural, it pays to keep in mind the extent of this process and maintain a healthy respect for what it involves.

A healthy respect for the biology

Back to the biology – the hormonal changes are just the beginning – they lead to a complex series of chemical processes that have various effects on the lining of the uterus. First the lining which was alive and getting thicker just the day before, has to be killed with special chemicals. Then the lining, which is basically dead tissue now,  detaches from the uterine wall.  The body is very proficient at dealing with this – it’s all part of the plan. Second, certain chemicals cause the lining to break up and crumble into small fragments (it’s very uncommon to get a whole piece of lining that looks like the finger of a glove come out during a period isn’t it?). Third, all the fragments are flushed away from the surface of uterine wall with blood, and sit inside the uterus.

Now, the openings from the uterus are only very small (yes plural – there are three openings – two leading out to the fallopian tubes and one leading out to the vagina through the cervical canal). The blood and the crumbled fragments of lining need assistance to be removed from the uterus, and this is provided by the muscles of the uterine wall squeezing (yes – the same contractions that occur with child birth) and the contents of the uterus come out as period blood [I did point out that if you looked at menstrual blood under a microscope that you would find a combination of blood cells and specialised cells from the lining of the uterus – but that may have been a bridge too far and the offer wasn’t taken up by mother or daughter].

Sounds quite exhausting doesn’t it? It can be, and the entire process demands lots of energy from the body. This doesn’t mean we should stop everything for a few days every month, but it’s part of having a healthy respect for the normal, but significant, biological processes occurring.

Inflammasomes and pro-inflammatory cytokines

Ok, onto the final piece of this story – what causes the lining to die off, crumble, be washed away and then squeezed out? Well, in response to the changing hormones, the uterus triggers the release of some pretty potent substances – amazing chemicals with names like inflammasomes and pro-inflammatory cytokines. Again, these are completely naturally occurring substances in the body – they’re involved in many immune and other protective responses and are really essential to keep us healthy. But the name might give you a clue as to what else they do – they’re also involved in inflammatory processes, and dealing with infections. Another effect of these chemicals is that they can sensitize our nervous system and this can lead to (more) aches and pains. Remember the last time you had a bad cold or a case of the ‘flu – it’s quite common to ache all over; and every month the increase in these chemicals can cause increased sensitivity in our nervous system and lead to aches and pains. Most important to know is that a vast majority of the time, aches and pains with periods are not associated with any kind of pathology or disease, but rather are related to the presence of these potent sensitizing and pro-inflammatory substances. But there’s even more! These same pro-inflammatory substances are associated with making you feel tired, grumpy, and generally poorly when you have the ‘flu – and for many women it’s the same when you have your period. And similar to women in labour, all that contracting of the uterus can lead to diarrhea, and cramping sensations.

So, that’s the truth of having a period – I think it’s important for you to understand that while it is completely normal and natural it is also complex biology involving really significant changes in your body and chemicals that we know are associated with feeling unwell and experiencing aches and pains. But again, there is nothing here that represent any kind of damage to your body or disease process, and there are things that we can talk about that you can do to help you stay healthy, active and reduce the pain associated with your periods.

Nobody ever explained all that to me

The young woman looked a bit overwhelmed, and her mum said “nobody ever explained all of that to me when I was young, I was told that it was just bleeding and that I’d have to learn to live with it all”. I explained that I knew it was a lot to take in, and some of it was even a bit confronting, but it’s something that every woman can and should understand because when we understand what’s happening in our bodies it leads to less worry, less fear, and even, less of the pro-inflammatory chemicals at the heart of the very process.

Of course there is even more complexity to the process, but I think this is a good start. What do you think? Would you add anything, change anything?

-Sonia Grover

Professor Sonia Grover has extensive experience in paediatric and adolescent gynaecology having worked in this field for over 20 years. She has been instrumental in establishing this subspecialty in Australia as well as in Asia and internationally. Professor Grover’s clinical interests include all aspects of young women’s’ reproductive health – including menstrual problems (excessive bleeding and/or pain), amenorrhoea, ovarian problems, congenital anomalies affecting the reproductive tract and reproductive hormones and the cyclic exacerbation of ‘non-gynaecological symptoms’ including cyclic seizures, asthma, and chronic fatigue. Professor Grover’s ResearchGate profile here.



Our thanks again to Professor Grover for sharing this great post


  1. Dear Sonia,
    I am so grateful too you for a most brilliant post and I will do my best to make it go viral.
    Big Hug

    1. sonia

      Understanding what is happening in our bodies is always helpful, so I am pleased this made sense to you Sally!
      This bit of womens lives – having periods – despite being a regular event in most womens’ lives – is never really taught or explained properly to anyone – not to women, but not even to medical students or gynaecology trainees!
      It would be great to see this change so that everyone understood this a bit better, so I am hoping that by writing this ( and some more to come!)that I may be able to help a few people.

  2. KK

    Great article. I am interested in the link between these ‘sensitising’ chemicals , stress and lifestyle factors, and the fluctuating levels of everyday pain in the case of females who live with persistent/chronic pain issues, and what can be done to mitigate that. I can have difficult periods, and also live with high impact chronic pain. I find some cycles also make my ‘normal’ pain, back and other more distal muscle spasms increase significantly. Sometimes to the point where it can be
    days or weeks to unwind/return to my baseline. Does not happen every month but there definitely seems to be a connection.

    1. sonia

      Great question, for which I am not sure there is a precise or quick answer – except to say that there are many things that influence the hormonal and chemical ‘soup’ that is happening in the lead up to having a period.
      We know that if you track actual hormone levels through a normal menstrual cycle, the levels will always be a bit different one month to the next.
      We also know that if you get stressed that your hormone levels can change quite dramatically. ( This explains why periods are different with the stress of exams, or in the setting of the physical stress of loads of exercise, or when you are really unwell with other health problems).
      But other things, like, what we eat, also influences the levels of some of these chemicals ( cytokines). Our gut microbiome may also play a role – either directly or indirectly as we now know that by using certain probiotics, anxiety levels can actually be changed. So it seems to make sense that these things would then also potentially interact with what is going on, either by changing the hormones or by changing what is going on in our brains ( which is possibly saying the same thing twice!).

      Many women who have other pain issues (like fibromyalgia and chronic fatigue) and other inflammatory conditions, such as inflammatory bowel disease, report that their symptoms flair up around period time. This makes sense to me – as the common element is the inflammasomes and cytokines. They are important (normal) chemicals to ‘make’ periods happen, but at the same time are contributors to the inflammation and messaging for these other conditions. So although these chemicals are released at ‘period time’ for one purpose ( making the period happen) – they end up in the body system stirring up problems elsewhere.

  3. Pilar

    I would add año explanation why some women don’t feel any pain while their period.

  4. Jo Hughes

    Brilliant post Sonia, I will be sharing. Also puts me in mind if the work Irene Tracy was doing in Oxford around the pain protectiveness that high levels of testosterone in men and progesterone and estrogen in women seemed to be showing as a pattern in her fMRI research in 2013, she talked about this at the NZSP conference in Wellington. Perhaps low levels of these hormones make us more pain susceptible?

  5. Sarah Kelly

    Thank you Sonia, this is a great explanation – and helps to explain why women with FMF (familiar Mediterranean fever – a systemic auto inflammatory disease) often have had bad inflammatory attacks with mensis.

  6. Nicola Cook

    Amazing explanation thank you. As a Physio with a healthy curiosity about pain pathomechanics and a woman who has had many gynae issues over the years – great to that level of information. Would love to know more!!!

    1. sonia

      Thankyou Nicole! – more coming – and happy to be writing. This whole area of womens health is so poorly explained and taught – even amongst health professionals- so it is a pleasure to share what I now know, combined with the evidence and the research! sonia

  7. Maria K

    This is a great post. Thank you. What a brilliant explanation. I saved it for future reference. I have always wanted to understand pre-menstrual headaches and migraines that I and some of my friends suffer monthly. I’d love to see a post on it or reference to it in the future, if possible? Thank you again.

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