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Pain in Labour: Your Hormones are Your Helpers

By Dr Sarah J Buckley © 2006

Imagine this. Your cat is pregnant, due to give birth around the same time as you are. You have your bags packed for hospital, and are awaiting the first signs of labour with excitement and a little nervousness.

Meanwhile your cat has been hunting for an out-of-the way place: your socks drawer or laundry basket- where she in unlikely to be disturbed. When you notice, you open the wardrobe door, but she moves again. Intrigued, you notice that your observation- even your presence- seems to disturb the whole process. And, wish as you might to get a glimpse into the mysteries of birth before it is your turn, you wake up the next morning to find her washing her four newborn kittens in the linen cupboard.

Why does birth seem so easy to our animal friends when it is so difficult for us? One obvious difference is the altered shape of the pelvis and birth outlet that is caused by our upright stance; our babies need to twist and turn to navigate these unique bends. Even our nearest cousins, the great apes, have a near-straight birth canal.

However, in every other way, human birth is like that of other mammals- those animals that suckle their young- and involves the same hormones- the body’s chemical messengers. These hormones, which originate in one of the oldest parts of our brain, cause the physical processes of labour and birth, as well as exerting a powerful influence on our emotions and behaviour.

Researchers such as French surgeon and natural birth pioneer Michel Odent believe that if we can be more respectful of our mammalian roots, and the hormones that we share, we can have more chance of a straightforward birth ourselves.

Labour and birth involve peak levels of the hormones oxytocin, sometimes called the hormone of love, and prolactin- the mothering hormone, both well-known for their role in breastfeeding. As well as these, beta-endorphin, the body’s natural pain-killer, and the fight-or-flight hormones adrenaline and noradrenaline play an important part in the birth process. There are many more hormonal influences on birth that are not well understood.

All mammals seek a safe place to give birth. This “nesting” instinct may be due to an increase in levels of prolactin, which is sometimes referred to as the nesting hormone. At this stage, as you may have observed with your cat, interference which the nest- or more importantly with the feeling of safety- will stall the beginning of labour.

Even after labour has started, there are certain conditions that will slow, or even stop the process. If the fight-or-flight hormones are activated by feelings of anxiety or fear, contractions will slow down. Our mammalian bodies are designed to give birth in the wilds, where it is an advantage to postpone labour when there is danger, and to seek safety.

Many women have had the experience of their labour stopping when they entered the unfamiliar surroundings of a hospital, and some women can be as sensitive as a cat to the presence of an observer. Giving birth away from our natural environment can cause the sorts of difficulties for us that captive animals experience when giving birth in a zoo.

Even hunger, which also causes the body to release fight-or-flight hormones, can stop labour from progressing. It makes sense, therefore, for women to eat if they are hungry in the earliest stages of labour. Unfortunately many hospitals have a policy that prevents labouring women from eating once they are admitted.

Oxytocin is the hormone that causes the uterus to contract during labour. Levels of oxytocin increase throughout labour, and are highest around the time of birth, when it contributes to the euphoria that a mother usually feels after an unmedicated birth, and to her receptiveness to her baby. This peak, which is triggered by sensations of stretching of the birth canal as the baby is born, does not occur when an epidural is in place. Administration of an epidural has been found to interfere with bonding between ewes and their newborn lambs by interfering with the oxytocin system, and there are some suggestions that this detachment may apply to women giving birth after an epidural as well.

Synthetic oxytocin is often given by drip- that is, directly into the bloodstream- when labour contractions are inefficient. Oxytocin given in this way does not enter the brain, and so does not contribute to the post-birth “high”, and in fact can interfere with a mothers own oxytocin system. Nipple stimulation is sometimes used to stimulate contractions because, like breastfeeding, this causes oxytocin levels to naturally increase.

Oxytocin has another crucial role to play after the birth. Oxytocin causes the contractions that lead to separation of the placenta from the uterus, and its release as the “after-birth”. When oxytocin levels are high, strong contractions occur that reduce the chance of bleeding, or post-partum haemorrhage.

Putting your newborn baby to your breast is the easiest way to increase oxytocin levels, but privacy is also very important during the hour following birth. This gives the opportunity for uninterrupted skin-to-skin and eye-to-eye contact between mother and baby - conditions that optimise oxytocin release.

Oxytocin helps us in our emotional, as well as our physical, transition to motherhood. Oxytocin contributes to the glow of new motherhood, giving us calm, connected feelings with our baby and those around us. Oxytocin also optimizes digestion and has a generally beneficial effect on other bodily processes: ideal for a breastfeeding mother.

The fight or flight hormones (adrenaline and noradrenaline) can interfere with oxytocin release during labour and after the birth. However they do have an important role to play in the second stage of labour, which is when birth actually occurs.

Early in second stage, when the cervix is fully open but the urge to push is not yet strong, a woman can feel the need to rest for some time. This is known as ‘transition’- or the ‘rest and be thankful’ time. After this, she may quite suddenly experience the dry mouth, dilated pupils and sudden burst of energy that are all characteristic of high levels of these hormones.

This burst gives a mother the energy to push her baby out efficiently; when unmedicated, women usually want to be upright at this time. Some traditional cultures have used this fight-or-flight effect to help women having difficulty with the delivery by surprising or shouting out at this stage, triggering a rapid birth. Threats of a caesarean or forceps delivery have been known to trigger this reflex for modern women.

Adrenaline/noradrenaline levels drop quickly after the birth, which can make a mother may feel cold or shaky. At this stage a very warm atmosphere is essential to keep these hormone levels low, and to allow oxytocin to work effectively to prevent bleeding.

The other major birthing hormone, prolactin is most noteworthy for its effects after the birth. Prolactin is the major hormone of breast milk synthesis. Suckling by the newborn baby increases prolactin levels; early and frequent suckling from the first days makes the breast more responsive to prolactin, which in turn helps to ensure a good long-term supply of milk.

Like the other hormones, prolactin has effects on emotion and behaviour. Prolactin helps us to put our babies’ needs first in all situations, and increases our vigilance, keeping us watchful and alert for our baby’s wellbeing. When prolactin is combined with oxytocin, as it is soon after birth and during breastfeeding, it encourages a relaxed and selfless devotion to the baby that contributes to a mother’s satisfaction and her baby’s physical and emotional health.

Beta endorphin (pronounced beet-a en-door-fin) is one of the endorphin hormones that are released by the brain in times of stress or pain, and is a natural equivalent to painkilling drugs like pethidine.

During labour, beta-endorphin helps to relieve pain, and contributes to the “on another planet” feeling that women often experience when they labour without drugs. Levels of beta-endorphin are reduced when drugs are used for pain relief.

Very high levels of beta-endorphin can slow labour by reducing oxytocin levels, which may help to ‘ration’ the intensity of labour according to our ability to deal with it. Moderate levels of beta-endorphin help us to deal with pain in labour, as well as encouraging us to follow our instincts. As part of the hormonal cocktail after birth, beta-endorphin plays a role in bonding between mother and baby, who is also primed with endorphins from the birth process.

Beta-endorphin also switches on learning and memory, perhaps explaining why we often remember our labour and birth in such amazing detail. Like oxytocin, endorphin hormones can induce euphoria and are also released during lovemaking and breastfeeding. In fact endorphins are actually present in breast milk, which explains the pleasure that babies can get after a breastfeed. After a natural labour, the new mother has high levels of beta-endorphin in her early milk, helping her baby with the stressful transition to life outside the womb.

So there you are, at the door, with your bag in your hand and a strong contraction. You remember the oxytocin and endorphins, which you also carry with you, and with your next relaxed breath, you breathe out all of your fear and tension. You’ve packed your new nursing bra, and you know that prolactin will come to your aid as well. As you take a last look around the house, you notice your cat.

She’s lying down as her kittens attach to her nipples, and as you catch her eye, she winks at you.

Sarah J Buckley is a GP, an internationally published writer on pregnancy birth and mothering, and currently full-time mother to her 4 children, all born at home. For more information and references on labour hormones, see Sarah’s book Gentle Birth, Gentle Mothering: The wisdom and science of gentle choices in pregnancy, birth and parenting and website www.sarahjbuckley.com

*top photo by Jodie Millar, bottom photo by Kristina Rogova.

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Pain in Labour: Your Hormones are Your Helpers