Dilation is the slow and gradual opening of the cervix during labour. The cervix needs to reach a width of 10cm to be considered fully dilated.

During the very late stages of pregnancy, the cervix is often dilated between one and three centimetres. A sign that the cervix is preparing for this initial phase of dilation is the loosening, and eventual loss of, the pregnant woman's mucus plug.

This thick plug stops bacteria entering the cervix during pregnancy. The loss of the mucus plug is known as a 'show'.

Once labour has commenced and is properly underway, with contractions coming every five to 10 minutes, the contractions of the uterus, combined with pressure from the baby, will continue the dilation of the cervix.

With each contraction, the cervix will move further into the pelvis and will become softer and thinner until it opens up completely. Once at 10cms, the woman will be ready to start pushing her baby into the world.

If a woman fails to dilate adequately, she is likely to be offered prostaglandin gel, which is inserted into the cervix, to stimulate dilation. If this fails, a syntocinon drip can also be administered.

Although intensely painful, dilation of the cervix should not result in the loss of fresh, red blood. If this happens, the woman could be at risk of placental abruption or placenta previa, both serious compilations of the placenta. To guard against this happening, a woman's discharge will be closely monitored during labour.

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