Stages of labour
The baby's descent into the birth canal during labour, measured by where the baby's head (or buttocks in a breech presentation) is in relationship to the mother's ischial spines (those 'pointy' parts that are at the midpoint of the pelvic bones). The first stage has initiation or completion of cervix effacement, and continues until full dilatation has occurred. The second stage: is the expulsive stage during which the foetus is pushed through the curved birth canal, lasting from full dilation of the cervix until the baby is born. The third stage extends from the birth of the baby until the complete expulsion of the placenta and membranes.