Most women face labour with some anxiety and trepidation, particularly with their first child. It should help you feel more prepared and relaxed if you have a good idea of what happens and why, even though no-one will be able to tell you exactly when.
We can break down labour into three main stages:
- Effacement and dilation
- Passing through the birthing canal
- Delivering the placenta
Effacement and dilation
For the nine months of your pregnancy your baby has been kept safe in a sealed environment by the sac of amniotic fluid and the mucous plug in your cervix. Before your baby can pass out of your womb through the cervix, the cervix will have to change completely. Not only will the mucous plug be lost, and often seen by pregnant women as a 'show', but the cervix walls will have to thin, soften and open out to ten centimetres to allow the baby's head to pass through. The thinning and softening process is known as 'effacement' and the later opening as 'dilation'.
Your thinned out cervix is pulled upwards by contractions in the walls of the uterus until the cervical canal disappears completely and leaves the way through into the birth canal, the vagina, free for your baby. When this happens you are said to be fully dilated.
This first part of this stage, known as early or latent labour, usually happens gradually over a number of weeks. But don't worry, that won't mean you'll be having painful contractions for weeks: if you efface and begin to dilate gradually then you either won't notice the contractions at all or they won't cause much discomfot. For some women effacement doesn't occur until just before labour begins in earnest, in which case labour is usually longer. With subsequent babies women often start to dilate earlier, well before strong and regular contractions begin. Once you're in the hospital or your midwife is with you, the midwife will probably check numerous times to see how far dilated you are. You won't be considered in active labour until you're at least 3cm dilated.
Once you are fully dilated (at 10cm) you move into the transition stage, at the end of which you'll feel the baby push down on your pelvic floor and feel the urge to push.
The time between when you're aware of being in labour - when you feel stonger and more regular contractions - to being fully dilated is usually between two and twenty hours.
Passing through the birthing canal
This is where the pushing starts. In this second stage of labour you help your contracting uterus push your baby through and out of the birthing canal.
You baby will be pushed head-first down the canal, as this is the largest part of his body. This takes on average around an hour, but for first babies it might well be as long as two hours and for later babies it could all be over in as little as fifteen minutes.
Delivering the placenta
Having sustained your baby for the last nine months the job of the placenta is now done and needs to be expelled so that your body can start getting back to normal.
Your body usually rests for five to fifteen minutes after your baby is delivered before delivering the placenta and the third stage is triggered by oxytocin, the hormone that is produced when you touch and hold your baby for the first time or put him to your breast.
In this third stage of labour the placenta first separates from the wall of the uterus, tearing through the blood vessels that join them. The uterus then begins contractions again - but relatively mild ones in comparison to the ones that just gave birth to your baby - and the placenta is eased out. Once the placenta is out your uterus contracts rapidly to its pre-pregnancy size, and closing off the open blood vessels of the placenta to prevent excessive bleeding.
