Module 4 Lesson 4 - 4

Parturition or labour is considered as having three stages although the events are a continuous process. Labour is separated into the dilation stage (uterine contractions begin), the expulsion stage (delivery of the fetus), and the placental stage (the discharge of the placenta).

Labour is initiated and sustained through nervous and hormonal control. Oxytocin and prostaglandin stimulation works through a positive feedback mechanism to promote further uterine contractions. Uterine contractions force the fetus down to the cervix and out through the birth canal. They cause the placenta to be expelled from the body after birth. If a normal vaginal birth is not possible, delivery of the fetus is accomplished surgically through Caesarean section (C-section).

After the fetus is delivered, it can no longer rely on its mother for air, food, or elimination of its own wastes. All the baby's body systems that perform these functions now begin working independently of the mother's support. For the infant to acquire nutrition, it must begin to breast-feed or suckle. The hormone prolactin causes the production of breast milk and the release of oxytocin; this, along with the suckling stimulation, results in the mammary glands secreting breast milk.