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Childbirth (also called labour, birth, or parturition) is the culmination of pregnancy, the emergence of a child from its mother's uterus. It can be considered the opposite of death, as it is the beginning of a person's life. Age is defined relative to this event in most cultures. The medical science of childbirth is obstetrics and a doctor who specializes in attending births is an obstetrician. Obstetricians are surgeons, who are trained to see childbirth as potentially pathological and in
need of routine interventions. Midwives see childbirth as a normal event for most women, and is best handled by as few interventions as possible. Midwives are trained to assist at births either through direct-entry or nurse-midwifery programs.
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. Occasionally the labour will begin with a rupture of the amniotic sac, the paired amnion and chorion ("breaking of the water"). The contractions will accelerate until they happen every two minutes although this is not always the case. The length of the contractions will also lengthen until at the end of the first stage they are typically lasting 70 - 90 seconds. During a contraction the long muscles of the uterus contract, starting at the top of the uterus and working their way down to the bottom. At the end of the contraction, the muscles relax to a state shorter than at the beginning of the contraction. This draws the cervix up over the baby's head. Each contraction dilates the cervix until it reaches 10+ centimetres (4") in width. During this stage, the expectant mother typically goes through several emotional phases. At first, the mother will be excited. Then, as the contractions become stronger, demanding more energy from the mother, the mother will become very serious and focused. However, as the cervix finishes its dilation, most mothers experience confusion or bouts of self-doubt. The latter is a reliable indication that the First Stage is nearly over. 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. A natural way to speed the onset of labor is sustained walking which wears down the amniotic sac at the end of a pregnancy.
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. In some cases the baby is breech meaning either the feet or buttocks are descending first. With properly trained staff and the right circumstances, even babies in the "breech" position can be delivered vaginally. There are several types of breech presentations the most common is where the baby's buttocks are delivered first and the legs are folded onto the baby's body with the knees bent and feet near the buttocks (full breech). Others include Frank breech, much like full breech but the babies legs are extended toward his ears, and footling or incomplete breech, in which one or both legs are extended and the foot or feet are the presenting part. Another rare presentation is a transverse lie. This is where the baby is sideways in the womb and a hand or elbow has entered the birth canal first. A vaginal birth should not be attempted, although in rare cases the arm can be pushed back up and the baby can be coaxed into the proper position. Immediately after birth, the child undergoes extensive physiological modifications as it acclimatizes to independent breathing. Several cardiac structures start regressing immediately after birth, such as the ductus arteriosus and the foramen ovale. The medical condition of the child is assessed with the Apgar score, based on five parameters. A "good start" refers to higher scores, while a child doing poorly with have low scores that do not improve rapidly over time.
The last stage of labour occurs in the fifteen minutes to hour after the baby is born. In this stage, the uterus expels the placenta (afterbirth). It is essential that the whole placenta is expelled, so the midwife will examine the placenta to ensure that it is intact. Remaining parts can cause postnatal haemorrhage or infection.
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. Many cultures feature initiation rites for newborns, such as circumcision or baptism, amongst others.
When the amniotic sac has not ruptured during labour or pushing, the infant can be born with the membranes intact. This is referred to as "being born in the 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, in some cultures was seen as protection against drowning, and the caul was often impressed onto paper and stored away as an heirloom for the child. With the advent of modern interventive obstetrics, premature artificial rupture of the membranes has become common and it is rare for infants to be born in the caul in Western births.
Due to the relatively large size of the human skull and the shape of the human pelvis forced by the erect posture, childbirth is more difficult and painful for human mothers than other mammals. Many methods are available to reduce the pain of labour, including psychological preparation, emotional support, epidural analgesia, spinal anaesthesia, nitrous oxide, opioids, and natural childbirth methods such as the Lamaze technique or Bradley Method. Each method has its own advantages and disadvantages.
Complications occasionally arise during childbirth; these generally require management by an obstetrician.
Non-progression of labor (longterm contractions without adequate cervical dilation) is generally treated with cervical prostaglandin gel or intravenous synthetic oxytocin preparations. If this is ineffective, Caesarean section may be necessary.
Fetal distress is the development of signs of distress by the child. These may include rising or decreasing heartbeat (monitored on cardiotocography/CTG), shedding of meconium in the amniotic fluid, and other signs.
Non-progression of expulsion (the head or presenting parts are not delivered despite adequate contractions): this can require interventions such as vacuum extraction, forceps extraction and 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.
Unanticipated heavy bleeding during or after childbirth is potentially lethal in places without immediate access to high level emergency care. Heavy blood loss leads to hypovolemic shock, insufficient perfusion of vital organs and death if not rapidly treated by stemming the blood loss and blood transfusion. Hypopituitarism after obstetric hypovolemic shock is termed Sheehan's syndrome.