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The process of childbirth


Hormones Involved During Childbirth

There are four main hormones that are responsible for the process of childbirth. Oxytocin, adrenaline, endorphins and prolactin. Other hormones involved are oestrogen, progesterone, prostaglandin and relaxin.


Oxytocin is the hormone of love and it is involved with lovemaking, fertility, contractions, birth and the release of milk in breastfeeding. It helps us feel good and it triggers nurturing feelings and behaviours. Receptor cells that allow your body to respond to oxytocin increase gradually in pregnancy and then increase a lot during labour. Oxytocin stimulates powerful contractions that help to thin and dilate the cervix, move the baby down and out of the birth canal, push out the placenta and limit bleeding at the site of the placenta. During labour and birth, the pressure of the baby against your cervix, stimulates oxytocin and contractions. Breastfeeding a newborn also releases oxytocin. During labour and birth, oxytocin levels can drop, causing contractions to stop or slow down, making labour take longer. To help increase oxytocin levels, it is important to have privacy, stay calm, comfortable, confident and free of any emotional or psychological anxieties.  Avoiding disturbances, such as unwelcome people or noise and uncomfortable procedures.  Staying upright and using gravity, so that your baby is pressed against your cervix and then, as the baby is born, against the tissues of your pelvic floor.  Avoiding epidurals, stimulating your nipples or sexual activity before birth and letting your baby suckle (breastfeed) shortly after birth, can all help keep oxytocin levels high.  Another way of helping oxytocin to flow freely, is by finding a quiet, dark room where you will not be disturbed. You and your baby need to feel safe when you are in labour and it is your body’s natural way of protecting you and your baby. When you feel safe, calm, not being watched and not under threat, oxytocin will increase and labour will progress well.


Adrenaline is the “fight or flight” hormone that humans produce to help ensure survival. Women who feel threatened during labour (for example, by fear or severe pain) may produce high levels of adrenaline.  Adrenaline can slow labour or stop it altogether. Earlier in human evolution, this disruption helped birthing women move to a place of greater safety.  Too much adrenaline can cause distress to the baby before birth, cause contractions to stop, slow or have an erratic pattern and lengthen labour.  Adrenaline can increase when the mother panics or experiences increased pain. Adrenaline often increases in women, when they receive interventions from health care professionals or if they need to go into theatre for a caesarean. If adrenaline increases, oxytocin can not flow freely and the body thinks that it is under attack and therefore provides the body with extra blood flow to the legs, arms and heart, getting it ready to fight or flight and run away from danger. Adrenaline reduces the blood flow to the uterus and the digestive system, sending more blood to the life-saving parts of the body when under threat.  Once adrenaline is released, in the body, the reduced blood flow to the uterus leads to less oxygen being pumped into the uterus, making the labour process more difficult, more painful and last longer. Therefore, it is important to stay calm, comfortable and relaxed when in labour.  Be informed and prepared.  Have trust and confidence in your body and your capabilities as a woman.  Have trust and confidence in your care providers and birth setting.  Be in a calm, peaceful and private environment and avoid conflict.  Be with people who can provide comfort measures, good information, positive words and other support.  Avoiding intrusive, painful, disruptive procedures is also important.


When you face stress or pain, your body produces calming and pain-relieving hormones called endorphins. You may have higher levels of endorphins near the end of pregnancy. For women who do not use pain medication during labour, the level of endorphins continues to rise steadily and steeply through the birth of the baby. (Most studies have found a sharp drop in endorphin levels with use of epidurals.)  High endorphin levels during labour and birth can produce an altered state of consciousness that can help you deal with the process of giving birth, even if it is long and challenging. High endorphin levels can make you feel alert, attentive and even euphoric (very happy) after birth, as you begin to get to know and care for your baby. In the early postpartum period, endorphins are believed to play a role in strengthening the mother-infant relationship. A drop in endorphin levels at this time may contribute to the “blues,” or postpartum depression, that many women experience for a brief time after birth.  Low levels of endorphins can cause problems in labour and birth by causing labour to be excessively painful and difficult to tolerate.  This leads health care providers to often respond to this problem with interventions, creating even lower levels of endorphins and oxytocin and increasing adrenaline levels.  You can enhance your body’s production of endorphins during labour and birth by staying calm, comfortable and confident, avoiding disturbances, such as unwelcome people or noise and uncomfortable procedures and by delaying or avoiding the use of epidurals.


Prolactin is known as the mothering hormone. It increases during pregnancy and peaks when labour starts on its own. Prolactin production during and after labour appears to be readying a woman’s body for breastfeeding. It may also play a role in moving labour along and helping the newborn adjust to life outside the womb. Prolactin is central to breast milk production. High levels of prolactin with early breastfeeding may foster women’s caretaking behaviours and adjustment to being a mother. This hormone may also support the infant’s healthy development. You can promote your body’s production of prolactin by waiting for labour to start on its own, minimising stress during labour and after birth, staying with your baby after birth and start breastfeeding early and thereafter on cue from the baby.       


What triggers labour?

During pregnancy progesterone hormones are high and prevents the uterus from contracting. Towards the end of pregnancy however, oestrogen levels start to rise until they are relative to the level of progesterone. At the same time, the baby is producing increased levels of oxytocin and it is thought that the increased level of oestrogen from the maternal brain, is the cause of this oxytocin increase. By the end of pregnancy, prostaglandin also increases. Prostaglandin is the hormone that softens the cervix and it also softens the pelvic ligaments, along with relaxin, enabling the pelvis to open more effectively during labour.

As the baby descends into the pelvis towards the end of pregnancy (lightening), the presenting part of the baby starts to apply pressure to the internal part of the cervix. This pressure when applied evenly, results in a reflex reaction that triggers the maternal brain to release increased levels of oxytocin. This in term stimulates contractions. As the contractions move down over the uterus, the pressure from them causes the baby’s head to become more flexed. As this happens, it allows the baby’s head to move even lower and apply greater pressure on the cervix, increasing the amount of oxytocin released.


Waters Breaking (Rupture of Membranes)

Sometimes at the beginning of labour, the bag of water surrounding the baby breaks (rupture of membranes). However, the most common time for this to happen is when the cervix is 7-10 cm dilated. If the membranes break in early labour, this is a hind water leak (waters coming from the top of the uterus, where the baby’s bottom is. Provided that baby is in a head down position). Sometimes it is hard to tell if a woman is leaking amniotic fluid or if they have passed a small amount of urine. The best way to tell is by the smell. Amniotic fluid does not smell, like urine does. Apply a pad and see if the trickle continues. If it does, then it is possible that the waters could be leaking. The waters should be clear or straw coloured. If they are red, brown, green or foul smelling, you should contact your doctor or midwife. If the waters have broken early, the biggest risk is infection. It is best to avoid any internal vaginal examinations and keeping out of environments that the maternal immune system is unfamiliar with to avoid any risks of infection if the waters have broken early.

If the waters break before labour begins it is called premature rupture of membranes. If waters break before 37 weeks of pregnancy, it is called preterm premature rupture of membranes. The membranes may break prematurely on their own for no obvious reason, or certain conditions can increase the risk of this happening. For example, vaginal examinations during pregnancy, excessive amniotic fluid, amniocentesis, smoking in pregnancy and uterine infection.


Mucus Plug

The cervix contains a small plug of mucus, which protects the baby and womb from infection. Sometimes when labour begins and the cervix softens and starts to dilate, the mucous plug comes away. The loss of the plug, called a show, does not indicate that labour has started, but it does indicate that the body is starting to get ready for labour. The plug could be clear, cloudy, yellow, brown, pink or red and looks like a thick lump of discharge or looks like snotty mucus. If you experience any heavy bleeding, you should contact your doctor or midwife.

Contractions or surges

For some women, the first sign of labour is the start of contractions. You may have been experiences Braxton Hicks or practice contractions for several days or weeks. These might feel uncomfortable, but they will not have any pattern and will be irregular. They will not change if you move around but may stop or slow down if you rest.

Labour contractions however have a regular pattern and will mostly start off gently, rise to a peak at the height of the contractions and then ease off again. When labour first starts, the contractions last for around 30-45 seconds. By the end of the first stage of labour, the contractions will last for around 90 seconds. The baby will not be born until contractions are lasting for around 90 seconds. You may not notice the first contractions or you may notice that they are very strong and frequent from early on. There is no set space in between contractions. Sometimes contractions can start off every 20-30 minutes and then build up so that they are coming every 2 minutes. For some women though, they are every 3-4 minutes from the beginning to the end of labour. Initially you will be able to talk through contractions, but as they progress you may need to concentrate on each one and take deep breaths to help you get through it.

When you experience a contraction, the muscle fibres at the top of the uterus shorten and draw up the cervix. Labour is divided into 3 stages.

Stage 1: From the first onset of labour until the cervix has fully opened to 10cm.

Stage 2: The expulsion of the baby through to complete delivery (the pushing stage).

Stage 3: The expulsion of the placenta.

The first stage of labour is often broken down into several separate phases. Early first stage (or latent stage), active first stage and transition.

Early First Stage

Dilation Length of Contractions Time between contractions Other signs What the body is doing
0-6 cm 30-45 seconds 3-20 minutes Talking during or between contractions. Still very together, possible backache, maybe a show, maybe some leaking fluid The cervix begins to soften and prepare for labour. It will begin to thin and dilate. This can occur over several hours, days or weeks.

Active First Stage

Dilation Length of Contractions Time between contractions Other signs What the body is doing
6-9 cm 60-80 seconds 2-10 minutes Begin to make some noise, rocking, focused, begin to look glazed. Finding it hard to talk Contractions will be much stronger and more regular. The cervix will be fully effaced and dilating more. The baby will be moving deep down into the pelvis and getting into a position to be born. First labours in the active phase can last from 8-16 hours. Subsequent labours can be much shorter.

Transition Stage

Dilation Length of Contractions Time between contractions Other signs What the body is doing
8-10 cm 90 seconds 2-5minutes Waters break, bloody show, legs shake, feeling hot or cold, nauseous, pressure in the bottom, losing confidence. Feeling like you want to give up, feeling like you need to pass a bowel motion, not caring about your appearance This is part of the active stage. The cervix is almost fully dilated and contractions are at their strongest. This stage can last from a few minutes, to an hour or more.

Second Stage

Dilation Length of Contractions Time between contractions Other signs What the body is doing
10 cm 90 seconds 2-5minutes An overwhelming urge to bear down, need to feel grounded. The cervix is fully dilated and the nature of contractions start to change as the baby moves into the birth canal. As the baby moves forward with each contractions, it slips slightly back. As the baby stretches the vaginal tissue and perineum, oxytocin increases to make contractions stronger. The second stage can take 1-2 hours for first labours and less than 1 hour for subsequent births.


Once the baby has been born, the third stage is the delivery of the placenta. Once your baby is born, the release of oxytocin will make the uterus contract and get smaller. This makes the placenta start to separate from the uterus. There are 2 options to consider when deciding how to deliver the placenta.Active Management which involves an injection of a drug called syntocinon or ergometrine into the thigh, soon after your baby is born. It speeds up the delivery of the placenta and happens around 30 minutes after your baby is born. Your midwife will massage your uterus and pull the placenta out by the umbilical cord. Active management can lower the risk of heavy blood loss (haemorrhaging), but it can make you feel sick and increase the risk of high blood pressure.  The cord will be cut between 1-5 minutes after giving birth. Early cord clamping reduces the amount of blood your baby gets after birth, by 20%. Physiological Management or Expectant Management. This is often used in midwife led units and at home births. It allows the placenta to be ready to come out mainly by pushing, gravity, contractions and sometimes by nipple stimulation. It is a natural way of delivering the placenta and does not use oxytocin injections. It can take up to one hour for the placenta to be born and skin-to-skin contact and breastfeeding are often used to help it along, by making your body produce more oxytocin. It involves sitting in an upright position to encourage the placenta to come out. Your midwife will monitor your blood loss and keep you and your baby warm. You will push the placenta out once it has separated and moved down to your vagina and the cord is clamped and cut after it has finished pulsating or after the delivery of the placenta. It is mostly used if you are at low risk of heavy blood loss.  You can change to active management at any time if you want to.You can also do a combination of active management and expectant management, which is called mixed management. For example, this could involve the process of active management, but delay clamping of the cord.