Childbirth (also called labour, birth, or parturition) is the process at the end of pregnancy by which a fetus leaves the mother's womb. It can be considered the opposite of death. Age is defined relative to this event in most cultures.
A typical human childbirth will begin the onset of the first stage of labour: contractions of the uterus, at first every 10-30 minutes and lasting about 40 seconds each, and the rupture of the amnion ("breaking of the water"). The contractions will accelerate until they happen every two minutes. Each contraction dilates the cervix until it reaches 10 centimetres (4") in width.
In the second stage of labour, the baby is expelled from the womb through the birth canal by both the uterine contractions and by powerful abdominal contractions ("bearing down"). The baby is most commonly born head-first. With difficulty, babies can be delivered in the "breech" position where the baby's rear is delivered first and the legs are folded onto the baby's body. Babies in a "footling breech" position should not be delivered via vaginal birth.
The last stage of labour occurs about a quarter to a half-hour after the baby is born; in this stage, the placenta or afterbirth is expelled.
Ocassionally, the head of a newborn infant may be covered with a thin, filmy membrane known as a caul. The caul is harmless and easily wiped away by the doctor or person assisting with the childbirth. In medieval times, a caul was seen as a sign of good fortune for the baby, and the caul was often impressed onto paper and stored away as an heirloom for the child.
The duration of labour varies wildly, but averages some 13 hours for women giving birth to their first child ("primiparae") and 8 hours for women who have already given birth.
Due to the relatively-large size of the human skull and the shape of the human pelvis forced by the erect posture, human childbirth is more difficult and painful for the mother than that of other mammals. A variety of anaesthetics have come into use to alleviate labour pains.
Complications occasionally arise during childbirth; this can require interventions such as Caesarian section. In the past, a great many women died during or shortly after childbirth (see puerperal fever) but modern medical techniques available in industrialized countries have greatly reduced this total.
The medical science of childbirth is obstetrics; a doctor who specializes in attending births is an obstetrician. A person who is not a doctor but who is specially trained to assist at births is a midwife.
Usually soon after birth the parents assign the infant its given names. They may have two sets of names in mind, one for if it is a boy, and one for if it is a girl.
Often people visit and bring a gift for the baby.