Childbirth: Labor, Delivery and Placenta

Childbirth is the culmination of a period of pregnancy with the expulsion of one or more newborn infants from a woman's uterus. The process of normal childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and birth of the infant, and the expulsion of the placenta.

Humans are bipedal with an erect stance. The erect posture causes the weight of the abdominal contents to thrust on the pelvic floor, a complex structure which must not only support this weight but allow three channels to pass through it: the urethra, the vagina and the rectum. The infant's head and shoulders must go through a specific sequence of maneuvers in order to pass through the ring of the mother's pelvis.

This video describes the three stages of labor: early labor, active labor, and delivery of the placenta and afterbirth.