Childbirth, also known as labour or delivery, is the completion of pregnancy, where one or more fetuses exits the internal environment of the mother vaginally or via caesarean section and becomes a newborn. In 2023, there were about 132 million human births globally. In developed countries, most births occur in hospitals, while in developing countries most are home births.
Vaginal birth is the most common mode of birth worldwide. It involves three stages of labour: the shortening and opening of the cervix during the first stage, descent and birth of the baby during the second, and the birth of the placenta during the third. During the first stage, contractions gradually become stronger and closer together. The postpartum period is the time of recovery for the mother and infant, in which both newborn and mother are monitored. All major health organisations advise that immediately after giving birth, regardless of the mode of birth, that the infant be placed on the mother's chest (termed skin-to-skin contact), and to delay any other routine procedures for at least one to two hours or until the baby has had its first breastfeeding.
Vaginal delivery is generally recommended as a first option. Caesarean section can lead to increased risk of complications and a significantly slower recovery. There are also many natural benefits of a vaginal delivery in both the mother and the baby. Various methods may help with pain, such as relaxation techniques, opioids, and spinal blocks. It is best practice to limit the number of interventions that occur during labour and delivery, such as an elective cesarean section. However, in some cases, a scheduled cesarean section must be planned for a successful delivery and recovery of the mother. An emergency cesarean section may be recommended if unexpected complications occur or little to no progression through the birthing canal is observed in a vaginal delivery.
Each year, complications from pregnancy and childbirth result in about 260,000 birthing deaths, seven million women have serious long-term problems, and 50 million women giving birth have negative health outcomes following delivery, most of which occur in the developing world. Complications in the mother include obstructed labour, postpartum bleeding, eclampsia, and postpartum infection. Complications in the baby include lack of oxygen at birth (birth asphyxia), birth trauma, and prematurity.
Signs and symptoms The most prominent sign of labour is strong repetitive uterine contractions. Pain in contractions has been described as feeling similar to very strong menstrual cramps. Crowning, when the baby's head becomes visible, may be experienced as an intense stretching and burning.
Back labour is a complication that occurs during childbirth when the feet or the bottom of the baby is visible first (bottom-first presentation), instead of being born head down (head-first presentation). This leads to more intense contractions, and causes pain in the lower back that persists between contractions as the back of the fetus' head exerts pressure on the mother's sacrum.
Another prominent sign of labour is the rupture of membranes, commonly known as "water breaking". During pregnancy, a baby is surrounded and cushioned by a fluid-filled sac (the amniotic sac). Usually, the sac ruptures at the beginning of or during labour. It may cause a gush of fluid or leak in an intermittent or constant flow of small amounts from a woman's vagina. The fluid is clear or pale yellow. If the amniotic sac has not yet broken during labour, the health care provider may break it in a technique called an amniotomy. In an amniotomy a thin plastic hook is used to make a small opening in the sac, causing the water to break. If the sac breaks before labour starts, it's called a prelabour rupture of membranes. Contractions will typically start within 24 hours after the water breaks. If not, the care provider will generally begin labour induction within 24 to 48 hours. If the baby is preterm (less than 37 weeks of pregnancy), the healthcare provider may use a medication to delay delivery.
Labour pain
Labor pains have both visceral and somatic components. During the first and second stages of labour, uterine contractions cause stretching and opening of the cervix. This, in turn, triggers visceral pain in the inner cervix and lower segment of the spine. Somatic pain is triggered at the end of the first and second stages of labour by pain receptors that supply the nerves on the vaginal surface of the cervix, resulting from stretching, distention, and tearing of the vagina, perineum, and pelvic floor. Compared to visceral pain, somatic pain is more resistant to opioid pain medication. Nitrous oxide may be used in hospitals and birthing centres for this reason.
Beyond physical pain, there are also well-documented biocultural and psychosocial aspects of labour pain and pain management. Pain is experienced distinctly by different cultures, and various culturally-relevant interventions can lessen labour pain, such as having extended female family members present during childbirth. Labour might be less painful in subsequent births, and this has been associated with lessened fear.
Pain management techniques during labour can include pain relief with medication (such as an epidural injection) or coping techniques (such as the Lamaze breathing).
Psychological
During the later stages of gestation, there is an increase in abundance of oxytocin, a hormone that is known to evoke feelings of contentment, reductions in anxiety, and feelings of calmness. Oxytocin is further released during labour when the fetus stimulates the cervix and vagina, and it is believed that it plays a major role in the bonding of a mother to her infant and in the establishment of maternal behaviour. The father of the child also has an increase in oxytocin levels following contact with the infant, and parents with higher oxytocin levels show being more responsive and "in synch" in their interactions with their infant. The act of nursing a child also causes a release of oxytocin to help the baby get milk more easily from the nipple.
Stages of labour
Labour is typically divided into three stages: the shortening and opening of the cervix during the first stage, descent and birth of the baby during the second, and the delivery of the placenta during the third. The first stage is characterised by abdominal cramping or back pain that typically lasts around half a minute and occurs every 10 to 30 minutes. The contractions (and pain) gradually becomes stronger and closer together. The second stage ends when the infant is fully expelled. In the third stage, the delivery of the placenta.
The postpartum period (sometimes called the fourth stage) involves recovery, the uterus beginning to contract to the pre-pregnancy state, and monitoring of the neonatal tone and vitals. All major health organisations advise that immediately following a live birth, regardless of the delivery method, that the infant be placed on the mother's chest, termed skin-to-skin contact, and delaying routine procedures for at least one to two hours or until the baby has had its first breastfeeding.
Station refers to the relationship of the fetal presenting part to the level of the ischial spines. When the presenting part is at the ischial spines, the station is 0 (synonymous with engagement). If the presenting fetal part is above the spines, the distance is measured and described as minus stations, which range from −1 to −4 cm. If the presenting part is below the ischial spines, the distance is stated as plus stations ( +1 to +4 cm). At +3 and +4, the presenting part is at the perineum and can be seen.
The baby's head may temporarily change shape (becoming more elongated or cone-shaped) as it moves through the birth canal. This change in the shape of the fetal head is called moulding and is much more prominent in women having their first vaginal delivery.
Cervical ripening is the physical and chemical changes in the cervix to prepare it for the stretching that will take place as the fetus moves out of the uterus and into the birth canal. A scoring system called a Bishop score can be used to judge the degree of cervical ripening to predict the timing of labour and delivery of the infant or for women at risk for preterm labour. It is also used to judge when a woman will respond to induction of labour for a postterm pregnancy or other medical reasons. There are several methods of inducing cervical ripening, which will allow the uterine contractions to effectively dilate the cervix.
Onset of labour
Definitions of the onset of labour include: Regular contractions at least every six minutes with evidence of change in cervical dilation or cervical effacement between consecutive examinations. Regular contractions occurring less than 10 minutes apart and progressive cervical dilation or cervical effacement. At least three painful regular contractions during 10 minutes, each lasting more than 45 seconds.
Common signs that labour is about to begin may include what is known as lightening, which is the process of the baby moving down from the rib cage with the head of the baby engaging deep in the pelvis. The pregnant woman may then find breathing easier, since her lungs have more room for expansion, but pressure on her bladder may cause a more frequent need to urinate. Lightening may occur a few weeks or a few hours before labour begins, or even not until labour has begun. Some women also experience an increase in vaginal discharge several days before labour begins when the "mucus plug", a thick plug of mucus that blocks the opening to the uterus, is pushed out into the vagina. The mucus plug may become dislodged days before labour begins or not until the start of labour.
While inside the uterus, the baby is enclosed in a fluid-filled membrane called the amniotic sac. Shortly before, at the beginning of, or during labour, the sac ruptures, commonly known as the "water breaking". Once the sac ruptures, the baby is at risk for infection, and the mother's medical team will assess the need to induce labour if it has not started within the time they believe to be safe for the infant.
First stage The first stage of labour is divided into latent and active phases, where the latent phase is sometimes included in the definition of labour, and sometimes not.
The latent phase is generally defined as beginning at the point at which the woman perceives regular uterine contractions. In contrast, Braxton Hicks contractions, which are contractions that may start around 26 weeks gestation and are sometimes called "false labour", are infrequent, irregular, and involve only mild cramping. Braxton Hicks contractions are the uterine muscles preparing to deliver the infant.
Cervical effacement, which is the thinning and stretching of the cervix, and cervical dilation occur during the closing weeks of pregnancy. Effacement is usually complete or near-complete, and dilation is about 5 cm by the end of the latent phase. The degree of cervical effacement and dilation may be felt during a vaginal examination.
The active phase of labour has geographically differing definitions. The World Health Organization describes the active first stage as "a period of time characterised by regular painful uterine contractions, a substantial degree of cervical effacement and more rapid cervical dilatation from 5 cm until full dilatation for first and subsequent labours". In the US, the definition of active labour was changed from 3 to 4 cm, to 5 cm of cervical dilation for mothers who had given birth previously, and at 6 cm for those who had not given birth before.Obstetric Data Definitions Issues and Rationale for Change , 2012 by ACOG. This was done in an effort to increase the rates of vaginal delivery.