What are labour contractions?
If you’ve thought about or heard about birth - like, at all - you’ve heard that labour is accompanied by contractions. Some folks who follow hypnobirthing choose to shift their language and use the term ‘wave’ instead, because language can strongly impact how we understand what’s happening in our bodies. But ultimately, they’re referring to the same thing happening in the body - a tightening and shortening of the muscles of the uterus. But what exactly happens during a contraction? How does the uterus know to contract? And how can understanding what is happening during a contraction change our experience of it?
Let's start by getting oriented with the parts of the body involved.
Uterus: The organ that a baby grows in. It is surrounded by many many muscles. When we refer to 'contractions' we are referring to the muscles of the uterus.
Cervix: The 'neck' of the uterus, that connects the uterus to the vaginal canal. If you think of a balloon, the cervix is the bit at the end you hold onto. Before labour begins, the cervix is closed, thick, hard and facing backwards.
Oxytocin: Often referred to as the ‘love hormone’, it is a hormone released during labour that stimulates contractions of the uterus. It also stimulates lactation postpartum.
During the last few days and weeks of pregnancy, the body is going through many changes to prepare for your baby to be born:
The cervix is tilting from a posterior position to an anterior position
The cervix is gradually softening
The cervix is thinning out (called effacement, measured from 0% - 100%)
The cervix is dilating (opening) from 0 - 10 cm's
Baby is dropping down into the pelvis.
Some, or much of this often happens without you even knowing. While we often hear a lot about ‘dilation’ of the cervix, (‘how many cm’s dilated are you???’) these other changes are happening simultaneously and often even before dilation begins.
Side note: If you get a cervical check at or around your due date and feel disappointed that your cervix hasn’t begun dilating, make sure to ask your provider about cervical position, softening, effacement and station of baby. These are all indications that your body is getting ready for birth.
So, what are labour contractions?
Contractions are the tightening and shortening of the muscles of the uterus. Just like when you do a bicep curl, the bicep muscle shortens and tightens. Similarly when the uterus muscles contract they also shorten and tighten. The difference is that the muscles of the uterus are controlled by our autonomous nervous system, which means we don’t have conscious or voluntary control over them. You can’t just ‘will’ your uterus to contract the same way you can your biceps (sorry!).
Overtime, uterine contractions gradually lead to the cervix thinning and opening so that the baby can move through the birth canal (vagina).
Why does labour start?
Unfortunately, the exact reason for the start of labour is still mostly unknown. We need to keep a little bit of magic to the whole process right? What we have at this point are a few scientific theories . It is widely believed that baby is the one that decides when they are ready to be born. One theory is that when when baby is ready to be born, a substance that they release when their lungs have developed called surfactant protein stimulates an inflammatory response that begins the process of labour. What follows is a beautiful dance between baby and birther, with hormones playing a huge role.
Contractions occur due to a positive feedback loop.
There are many hormones at play during both pregnancy and labour. One of these is estrogen which increase oxytocin receptors on the uterus. Remember, oxytocin is the hormone responsible for contractions to occur. When labour begins, oxytocin is released from the pituitary gland in spurts, attaching to the receptors on the uterus causing it to contract.
The contractions of the uterus muscles do two things - they pull the uterus muscles up while squeezing the baby down so that baby's head (ideally) presses on the cervix encouraging the cervix to open.
This in turn, stimulates receptors on the cervix that send a message up to the brain to release more oxytocin. The brain receives this message, releases more oxytocin and the process is repeated again. Each contraction the baby presses down further and further, putting more pressure on the cervix. At the same time, as the uterus muscles are pulling, they are encouraging the cervix to open, to thin out and to soften.
This feedback loop continues throughout your labour and is halted when the baby is born, or if something disrupts this delicate process.
Are labour contractions ‘painful’?
The million dollar question. To fully answer this, we need to dive deep into pain science (which we won’t be doing in this post). But what is important to understand is that pain is a very complex, multifactorial and extremely personal experience. It is your brain’s interpretation of what is happening in your body.
In life, we often associate pain with something being wrong. Stubbing your toe, injuring your back, breaking your arm. In labour however, the intense sensations that you experience are for a very purposeful and positive reason.
I like to advise my clients to take the word pain out of their vocabulary when thinking about labour contractions. Will you experience intense sensations in your body? Absolutely. But if we dissociate these sensations from our previous experiences with pain, our brain can interpret them differently.
I also like to share this PAIN acronym. Labour sensations are different from the sensations you experience with an injury because they are:
Purposeful:the strong contractions that you are feeling have a very important purpose of helping you birth your baby. The specific sensations can also be useful in helping tell your body what it needs. For example, often when a baby is in a posterior position (OP) the birther will feel the contractions in their back and for many, the automatic reaction is to move onto hands and knees. This movement can actually aid baby is changing positions.
Anticipated - we know that labour will bring with it intense sensations and we have time to prepare ourselves both physically and mentally for what is to come (of course if it’s your first time birthing you can never fully prepare for what it will feel like). We can arm you with a toolkit of comfort measures and mindset practices to cope with the sensations of labour.
Intermittent - typically each contraction will start and end, and there will be a rest period in between. While these rest periods get shorter and shorter as labour progresses we can use them strategically to really rest, recharge and prepare for the next contraction.
Normal - typically we associate pain with something going wrong but in labour, these sensations are a good indication that everything is going exactly as it should be.
It’s important to remember that there is a difference between pain and suffering. I like to tell my clients, our job isn’t to decrease the sensations you are feeling in labour. Our job is to enhance your ability to cope with what you are feeling in your body. Suffering occurs when you are no longer able to cope with what you are experiencing, and it involves an interpretation or judgement of the physical sensation. In another post, I will share some comfort measures that can be used to enhance your ability to cope with the physical sensations of labour.
