Hormones In Labour
Childbirth requires a complex and exquisite interplay of hormones, emotions and mechanics.
A woman must feel safe and supported while being allowed to enter a place deep within herself in order to give over to her body, and work with her most powerful contractions to bring a brand new being into the world. So how do our hormones help in labour?
Progesterone, oestrogen, oxytocin, prostaglandins, endorphins, cortisol, and adrenaline all play a part in initiating, establishing and maintaining a normal labour. Sarah Buckley (2009) describes these hormones of birth as an ecstatic cocktail prescribed by nature to aid birthing mothers. Dim lighting, a quiet and private space, warmth and a feeling of un-hurriedness allow these hormones to work in the best possible way. In her introduction to Michel Odent's book, Birth Reborn (2005), Shelia Kitzinger says, "The right environment in birth is exactly the same as the environment in which to make love".
Progesterone, produced by the placenta and responsible for suppressing uterine excitement during pregnancy, drops away at the onset of labour. This allows the effects of oestrogen to take over. Oestrogen increases the number of uterine oxytocin receptors in late pregnancy with these levels rising at about 34 weeks.
Oxytocin, also known as the love hormone, causes contractions of the uterus. It is stored in the posterior pituitary and released in pulses into the bloodstream. This happens initially every 3-5 minutes but becomes more frequent as labour progresses. Also known as the hormone of love, oxytocin builds up over the course of labour and is at peak levels as the baby is born. Oxytocin promotes prostaglandin release. Prostaglandins are produced locally in the uterus and stimulate it to contract. They also have a role in softening the cervix in order for it to efface and dilate. As the vagina is distended, pressure is exerted on the cervix and the pelvic floor muscles; and as the perineum is stretched during crowning, oxytocin production is increased (Robertson 2006). However fear and anxiety, distractions during labour, induction, epidural and episiotomy all work to inhibit the production of this hormone.
Endorphins are the body's natural pain killing hormones and are secreted by the pituitary gland. In a labour where drugs are not used endorphins are present at a very high level and allow a woman to go beyond her pain. They are produced in response to physical stress and act to restore a natural balance within the body. Babies too secrete endorphins during labour from their own pituitary as well as placental tissue and membranes (Buckley, 2009). The three main effects of endorphins are to modify pain, create a sense of well-being, and alter perception of time and place (very handy to have on board during a long labour!).
As labour progresses endorphin levels increase and as they increase the mother may seem to become withdrawn and even 'spaced out' in response to these rising levels. Endorphin production is at its peak during transition - a time where contractions can seem unrelenting and very painful. Once through transition a woman may experience a resting phase before passing into the second stage of labour and because her endorphin levels are still very high she may experience a surge of energy or a 'second wind' which will help her cope with the work of pushing.
The characteristic state of euphoria that a woman experiences immediately following labour is also attributable to high levels of endorphins. The mother will have feelings of elation, her energy levels will be high and both she and baby will be very alert. This is hugely important when it comes to bonding and the establishment of breastfeeding. Clever Nature ensuring the physical and emotional well-being of babies in order that they go on to also successfully reproduce.
Epidurals in labour inhibit endorphin production and in fact seem to remove it from the mothers system for the duration of the anaesthetic. Robertson (2006) explains, "Since endorphin is produced in nerve endings as a response to physical stress, anaesthetising the nerve endings will limit endorphin production. Without the apparent physical stress on the body (the woman is now numb) the production of endorphins declines and this can be observed by a change in her behaviour. Following administration of an epidural, many women 'sober up' and the dreamy 'spaced out' behaviour vanishes" (p93). Should the epidural wear off the woman may find she just cannot cope as her endorphin levels are not high enough to help her with the pain. As it takes some time for these levels to build again she may ask for a top up. Of course this means she will be numb again and may have trouble when it comes time to push.
Adrenaline, the body's fight or flight hormone will be produced in times of extreme stress or fear.. If adrenaline is produced at a high level in early labour this can be enough to slow or even stop labour. This effect occurs as blood is diverted to the major blood groups in order for the flight or fight reaction to take place. If levels stay high they can impact on blood flow to baby and result in hypoxia. As adrenaline increases, oxytocin decreases. Adrenaline also prevents the cervix from further dilating in order that the baby not be born at this apparently dangerous time. The uterus begins to contract in an uncoordinated manner which increases pain. The increased pain stimulates more release of adrenaline. Talk of possible interventions, increased pain, a poor environment or even just being in a hospital can all lead to excess production of adrenaline. High adrenaline levels lead to longer labours so it is essential that women have the tools and education to stay as calm and relaxed as possible.
So mama, relax and let those hormones do their thing. A woman’s body is made to give birth so all you need to do now is trust in the process. With the aid of your support people do what it takes to keep your fear at bay; allow those endorphins to wash through you and help you find your zone. Massage, visualisations, dim lighting, movement, music, water and warmth are just some of the ways to chase adrenaline out and allow endorphins in. Labour and birth provide a magical and empowering ride.
Buckley, SJ. (2009). Gentle Birth, Gentle Mothering. California: Celestial Arts.
Odent, M. (2005). Birth Reborn.
Robertson, A. (2006). Empowering Women: Teaching Active Birth. NSW: Birth International