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As part of my hypnobirthing teacher training, I was asked to write a resource explaining the hormones of labour - So I thought why not kill two birds with one stone and create something useful to you as well?
Let's delve into the main hormones of labour and how they can be influenced both positively and negatively.
A quick word on how your body is preparing for labour at the end of your pregnancy!
Increasing hormone receptors in the areas that count!
Increase of oxytocin receptors on your uterine muscle
Increase of oxytocin receptors in your brain
Increase of endorphin receptors in your brain
Increase of oxytocin and prolactin receptors in your breast tissue
Rising estrogen levels
You can see here that your body is working hard to create the most effective environment for a safe labour and birth, and a scheduled birth such as induction or cesarean can mean your baby is born before all these foundations have been fully laid down.
Relaxin
Relaxin, aptly named for its role in relaxing the ligaments of the pelvis, assists in preparing the body for childbirth.
A peak in early pregnancy helps soften our ligaments for growth, and then another peak at the end of pregnancy helps widen the pelvis.
Produced by the placenta, relaxin helps soften the cervix and widen the birth canal. This hormone ensures that the maternal body is ready for the physical demands of labour and delivery.
Prolactin
Prolactin, known for its role in milk production, also plays a part in childbirth. This hormone rises towards the end of pregnancy, preparing the body for breastfeeding. Additionally, prolactin promotes relaxation and bonding between the mother and the newborn, fostering a nurturing environment during the postpartum period.
Prolactin rises throughout pregnancy in the mother's blood stream, dipping as they go into labour and then rising again as birth nears and continues to rise and fall for several hours postpartum.
Prolactin levels are raised by both oxytocin and endorphins, letting it know when it is needed for that initial mother-baby bond and to help initiate the breastfeeding journey.
Stress in labour can reduce prolactin levels, potentially affecting the breastfeeding relationship.
Prostaglandin
Prostaglandins, lipid compounds with hormone-like effects, are involved in the initiation of labour. They help soften and thin the cervix, preparing it for dilation and effacement. Prostaglandins also promote uterine contractions, contributing to the progression of labour.
Prostaglandin levels are increased by the presence of oxytocin, they work together to increase uterine contractions and thin the cervix!
Paracetamol (acetaminophen) is a nonsteroidal anti-inflammatory drug (NSAID) that can inhibit prostaglandin (PG) synthesis in some tissues, its often suggested to mums as a first-line pain relief option in early labour, but this is when we need our prostaglandins most!
Melatonin
Not the first hormone you might think of, but melatonin has quite the influence on your labour and may even help decide what time your contractions begin! Known as the "sleep hormone," melatonin helps regulate the sleep-wake cycle and is essential for maintaining a healthy circadian rhythm.
Melatonin is an effective cheerleader for Oxytocin, one study showed that 1 unit of Melatonin, plus one unit of Oxytocin was as effective as 100 units of Oxytocin at creating uterine contractions. (J Pineal Res. 2019)
It's no surprise that following the onset of spontaneous labour, the most common time to give birth is between 1 am and 8 am with the peak at 4 am.
Melatonin is at its peak between 2 am and 4 am.
Melatonin levels are disrupted by light, so maybe the idea of keeping your birth space dim is less to do with aesthetics and more to do with science!
Let's get into the hormones of labour now...
Oxytocin
Referred to as the "love hormone" or the "bonding hormone," oxytocin is a powerhouse during labour and birth. It stimulates uterine contractions, connecting to the receptors that have been increasing in number towards the end of pregnancy. Facilitating the progression of labour. Oxytocin also enhances feelings of connection and trust, promoting maternal-infant bonding and milk ejection during breastfeeding.
Oxytocin has a positive effect on its production, creating a positive feedback loop that helps labour progress!
It has a calming effect (remember those receptors in your brain!)
Stress reduces oxytocin levels, as it is the hormone of love and intimacy, that is the environment it needs to thrive!
Endorphins
Endorphins, often called the body's natural painkillers, come into play during labour. Released in response to stress or pain, endorphins help alleviate discomfort and create a sense of well-being. Their presence during childbirth can lessen the perception of pain, allowing mothers to navigate the intensity of labour with greater ease, creating an altered sense of consciousness.
High levels of endorphins can actually stall labour, so high levels of stress or pain can cause contractions to slow.
But low levels can also have a slowing effect as there isn't enough pain relief which causes stress, so it's a balancing act!
Forms of pain relief can affect your levels of endorphins as they affect your perception of pain, which can be good as means you are in less pain, however, it can have downstream impacts on the mood-altering properties of the endorphins!
Adrenaline
While oxytocin promotes relaxation, adrenaline, the hormone associated with the stress response, can hinder the progress of labour. High levels of adrenaline, often triggered by fear or anxiety, can slow down contractions and increase discomfort. Sending your blood to your extremities and away from your uterus to prepare you for fight or flight, starves your uterus of oxygen making things more painful and less effective.
Finding ways to reduce stress and create a calm birthing environment can help keep adrenaline in check. This can be very personal to you, and working during pregnancy to identify what causes your stress response can be a very important piece of preparation work.
However a peak of adrenaline just before birth (transition) can help bring the monther back into the room, ready to meet her baby, and help the baby to make the transition from womb to world. (There you are, the villan redemption arc!)
In conclusion, the intricate dance of hormones throughout pregnancy and childbirth showcases the body's remarkable adaptability and design. Understanding the roles of their hormones can empower expectant mothers to positively influence their birthing experiences. By fostering a supportive environment and managing stress levels, mothers can harness the power of these hormones to navigate labour with strength and resilience.
References
J Pineal Res. 2019 May ; 66(4): e12566. doi:10.1111/jpi.12566.
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