Labor falls into three distinct stages

The first, and longest, lasts an average of fourteen hours in a first birth, but less for later births, and involves the violent contractions which move the fetus into the birth canal. The second stage may last from a few minutes to two hours and in this stage, the contractions slow down as the baby begins its journey to the outside. The third stage may take from ten to forty-five minutes and is the process of expelling the placenta and the umbilical cord.

The first stage of birth will produce persistent, regular contractions as the uterine muscles shorten upward to force the fetus down and pull the cervix upward. As this stage progresses, the contractions become more intense, occurring about every minute or two to force the fetus down into the birth canal.

In the second stage, the contractions slow down and the baby starts moving to the outside world; the mother, working along with the contractions, pushes the baby down the birth canal.

During normal birth, the head appears first, the shoulders turn, and more contractions push the baby out. The baby's mouth and nasal passages are cleared of mucus, the baby breathes, cries, and is given to the mother. When the umbilical cord ceases to pulsate, it is clamped and cut. In 3%% of births, the baby comes "breech," that is, feet and buttocks first. It is sometimes possible to turn the baby before it moves into the birth canal; if not, a caesarean section, or surgical removal, is performed. Breech deliveries are dangerous to both the mother and the child. In the third (and final) stage of labor, the uterus continues to contract to expel the placenta and the umbilical cord, and the process of birth is complete.

By the time a baby is born it already knows how to nurse, since it has been sucking its own thumb for months. When the baby begins to suck the mother's nipple, it accomplishes two things. First, it stimulates the nerves at the base of the nipple to shut off bleeding vessels and forestall excessive bleeding from the uterus. At the same time, sucking acts upon the breast to force early milk out of the storage area into the breasts and into the ducts leading through the nipple so that the baby can feed.