Childbirth (also called labour, birth, partus or parturition) is the culmination of a human pregnancy with the emergence of a newborn infant from its mother's uterus.
A woman is considered to be in labour when she begins experiencing regular, strong uterine contractions, accompanied by changes of her cervix — primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labours. When the baby is born its birth weight is determined.
First Stage: contractions
A typical human childbirth will begin with the onset of contractions of the uterus. The frequency and duration of these contractions varies with the individual. The onset of labour may be sudden or gradual. A gradual onset with slow cervical change towards 3 cm (just over 1 inch) dilation is referred to as the "latent phase". A woman is said to be in "active labour" when contractions have become regular in frequency (3-4 in 10 minutes) and about 60 seconds in duration. The now powerful contractions are accompanied by cervical effacement and dilation greater than 3 cm. The labour may begin with a rupture of the amniotic sac, the paired amnion and chorion ("breaking of the water"). The contractions will accelerate in frequency and strengthen. In the "transition phase" from 8 cm–10 cm (3 or 4 inches) of dilation, the contractions often come every two minutes are typically lasting 70–90 seconds. Transition is often regarded as the most challenging and intense for the mother. Some mothers say things like "I give up, I want to stop now. Forget this!" It is also the shortest phase.
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 becomes completely dilated, often referred to as 10+ cm (4") in diameter.
During this stage, the expectant mother typically goes through several emotional phases. At first, the mother may be excited and nervous. Then, as the contractions become stronger, demanding more energy from the mother, mothers generally become more serious and focused. However, as the cervix finishes its dilation, some mothers experience confusion or bouts of self-doubt or giving up.
The duration of labour varies widely, but averages some 13 hours for women giving birth to their first child ("primiparae") and 8 hours for women who have already given birth.
If there is a significant medical risk to continuing the pregnancy, labor induction may be necessary. As this carries some risk, it is only done if the child or the mother are in danger from prolonged pregnancy. 42 weeks gestation without spontaneous labour is often said to be an indication for induction although evidence does not show improved outcomes when labour is induced for post-term pregnancies. Inducing labour increases the risk of cesarean section and uterine rupture in mothers that have had a previous cesarean section.
In the second stage of labour, the baby is expelled from the womb through the vagina by both the uterine contractions and by the additional maternal efforts of "bearing down," which many women describe as similar in sensation to straining to expel a large bowel movement. The imminence of this stage can be evaluated by the Malinas score.
The baby is most commonly born head-first. In some cases the baby is "breech" meaning either the feet or buttocks are descending first. Babies in the breech position can be delivered vaginally by a midwife, though in some areas finding an experienced willing attendant can be difficult.
There are several types of breech presentations, but 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 or 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. While babies who present transverse will often move to a different position, this is not always the case.
The length of the second stage varies and is affected by whether a woman has given birth before, the position she is in and mobility. The length of the second stage should be guided by the condition of the fetus and health of the mother. Problems may be encountered at this stage due to reasons such as maternal exhaustion, the front of the baby's head is facing forwards instead of backwards (posterior baby), or extremely rarely, because the baby's head does not fit properly into the mother's pelvis (Cephalo-Pelvic Disproportion (CPD)). True CPD is typically seen in women with rickets and bone deforming illnesses or injuries, as well as arbitrary time limits placed on second stage by caregivers or medical facilities.
Immediately after birth, the child undergoes extensive physiological modifications as it acclimatizes to independent breathing. Several cardiovascular structures start regressing soon after birth, such as the ductus arteriosus and the foramen ovale. In some cultures, the father cuts the umbilical cord and the infant is given a lukewarm bath to remove blood and some of the vernix on its skin before being handed back to its parents.
The medical condition of the child is assessed with the Apgar score, based on five parameters: heart rate, respiration, muscle tone, skin color, and response to stimuli. Apgar scores are typically assessed at both 1 and 5 minutes after birth.
Third stage: placenta
In this stage, the uterus expels the placenta (afterbirth). Breastfeeding the baby will help to cause this. The mother normally loses less than 500 mL of blood. Blood loss will be greater if the umbilical cord is used to tug on the placenta. It is essential that the placenta be examined to ensure that it was expelled whole. Remaining parts can cause postpartum bleeding or infection.
Medical professionals typically recommend breastfeeding of the first milk, colostrum, to reduce postpartum bleeding/hemorrhage in the mother, and to pass immunities and other benefits to the baby.
Parents usually assign the infant its given names soon after birth.
Often people visit and bring a gift for the baby.
Many cultures feature initiation rites for newborns, such as naming ceremonies, baptism, and others.
Mothers are often allowed a babymoon period where they are relieved of their normal duties to recover from childbirth and establish breastfeeding with their babies. Length of this period varies. In China this is 30 days and is referred to as "doing the month".
A birth story may be written, detailing the events of the birth. The story may be posted to a blog or web forum.
Complications and Risks of Birth
Some of the possible complications are:
- Heavy bleeding during or after childbirth.
- Non-progression of labour (long term contractions without adequate cervical dilation) is generally treated with intravenous synthetic oxytocin preparations. If this is ineffective, Caesarean section may be necessary. Changes in maternal position is effective in many cases.
- 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 or Caesarean section.
- Lacerations can be painful. An episiotomy is occasionally necessary to avoid tears involving the anal sphincter, but its routine use—once normal—has now been shown to be harmful.
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