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Cervical mucus
Conception Aug 24, 2020
5 Minutes

Cervical mucus playing a bigger role in fertility than we thought?

Recent pioneering research has added yet another piece to the fertility puzzle. This time it lies with cervical mucus. Which appears to play a much more pivotal role in fertility than we had realised previously. In fact, it may play a significant role in cases of unexplained infertility which is around 30-40% of infertility cases. Actively selecting on hindering its passage to fertilisation. Here are ten things to know as well as some tips for taking care of yours.   

Cervical mucus: the ultimate gate keeper?! 

Most of us know a few basics about this wonderful stuff. Specifically that it is one of the best indicators of impending ovulation. Most of us know to watch for the ‘egg white’ consistency. This happens as the viscosity and elasticity changes to allow passage of sperm for fertilisation. However, research shows there is a LOT more that this wonderful stuff controls. In fact, it appears that it may play a role in actively selecting or rejecting our choice of partner!

Here are some things to know:

ONE: cervical mucus is the first barrier – it appears to play a material role in sperm function: 

The stats say that it can impact sperm function by up to 30%. It is the first barrier and appears to regulate how it easily it swims and whether or not it gets stored which can enhance or detract from fertility potential. 

TWO: very few actually get through… 

Did you know that approximately only 1 of every 1m spermatozoa is able to pass to the lower reproductive tract of women and reach the oviducts?! Cervical mucus appears to either enhance or detract from this. 

THREE: Weeding out the weak:

It acts as a selective barrier for poorly motile or abnormal sperm. 

FOUR: Cervical mucus appears to be able to enhance sperm function: 

Cervical mucus ‘may simultaneously aid migration of functionally normal sperm and serve as a selective barrier for abnormal sperm cells’. In fact, it has been shown to maintain and even enhance sperm function for those that are ‘selected’.

How does it do this? 

There is evidence of ‘stimulation of hyper activation’ which is believed to be a good thing for fertilisation. It is also believed to prevent ‘spontaneous or premature acrosome reaction’ which may be detrimental to sperm fertilisation capacity. 

FIVE: now this is where it gets really clever. Cervical mucus playing a role in creating stronger children?! 

Recent research shows that it could even play a role in selecting the ‘right’ mate from an immunological point of view.

What does that mean?

It appears that it filters out or promotes passage of sperm depending on signals from the immune system. Research suggests that it may actively promote sperm from a partner that has a different immune system to your own. This in theory would allow the child to have a more diverse immune system and be better equipped to fight off infection. Pretty clever. 

SIX: how? immune signalling proteins are present… 

Evidence suggests that cervical mucus contains a ‘wide array of immunological molecules, including soluble HLAs’. What are these? Human Leucocyte Antigen (HLA) are a group of proteins which help the immune system detect and understand it’s own cells from foreign cells. What to attack and what to leave alone. They are also present on human sperm. 

SEVEN: cervical mucus as a check on immune system compatibility? 

We know from previous research that attraction is part of this process. It appears that cervical mucus may be another ‘sense check’. Research has shown that we are more attracted to certain body odours for example which may signal immune system compatibility. From an evolutionary stand point we want an immune system that is dissimilar to our own. That can give a child a more diverse immune system which would be better at fighting off infections.

These signals appear to promote cervical mucus to aid or to detract from the fertilisation process. Based on immune system compatibility. That is some seriously clever gate keeping!

EIGHT: a more diverse immune signal may promote better sperm motility:

The research backs this up. Showing that sperm had higher survival rates in HLA dissimilar male-female combinations than those who were more similar. In fact it appeared to play a role in sperm motility which was higher on average in those who had more diversity. 

NINE: cervical mucus may selectively store sperm to enhance chances of fertilisation:

There is even evidence that it could act to enhance longevity of sperm by promoting storage. Potentially enhancing chances of fertilisation. Once again where immune systems are compatible: 

‘Cervical mucus may selectively store the sperm of immunologically compatible males, possibly for later use in fertilisation.’ 

TEN: so how do we make sure our own cervical mucus is in the ‘best shape’? 

Clearly there isn’t much we can do on the immunity front! Although there is evidence that who we deem ‘attractive’ in the first instance is already part of this clever process. However what we can do is to make sure it is in the best shape possible. Three easy things to do:


This is a really simple one and good for health in general of course! One study looked at daily changes in mucus water concentration (hydration) prior to the LH surge which should trigger ovulation. It then looked at the ability of sperm to get through. Interestingly, peak water content should occur 3-4 days before the LH peak and there was a ‘strong correlation between mucus hydration and sperm penetrability once the value of hydration rose to approximately 97.5%.’ 

As we know – staying hydrated is never a bad thing! 

Watch your lubrication, many of which inadvertently hurt conception: 

Did you know that many ‘recommended’ lubricants have actually been shown to hinder fertility? Part of this is labelling regulation and part of this is lack of education on the subject. In fact some of the biggest and best known brands are top culprits. Here is our in depth guide as to what to watch for when choosing your lubricant. 

Keep your hormones in check: 

Avoiding hormone disruptors and helping your body do what it does best is of course a good idea for health on the whole. However, hormonal imbalances can and do impact cervical mucus and ovulation. The main things to avoid are pretty obvious: plastics (BPA), pesticides, high BMI, phytoestrogens, processed foods, fragranced cosmetics and heavy sugar intake. A good diet full of fibre, probiotics and whole foods plus regular exercise are all helpful. For much more on hormone disruptors click here. 


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.









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