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Childbirth
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Childbirth (also called labour, birth, partus or parturition) is the culmination of a human pregnancy or gestation period with the delivery of one or more newborn infants from a woman's uterus. The process of normal human childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and delivery of the infant, and delivery of the placenta.. In some cases, childbirth is achieved through caesarean section, the removal of the neonate through the abdomen, rather than through vaginal delivery.
use humans are bipedal with an erect stance and have, in relation to the size of the pelvis, the biggest head and shoulders of any species, human fetuses are adapted to make birth possible.
The erect posture causes the weight of the abdominal contents to thrust on the pelvic floor, a complex structure which must not only support this weight but allow three channels to pass through it: the urethra, the vagina and the rectum.
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Encyclopedia
Childbirth (also called labour, birth, partus or parturition) is the culmination of a human pregnancy or gestation period with the delivery of one or more newborn infants from a woman's uterus. The process of normal human childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and delivery of the infant, and delivery of the placenta.. In some cases, childbirth is achieved through caesarean section, the removal of the neonate through the abdomen, rather than through vaginal delivery.
The mechanics of vaginal birth
Because humans are bipedal with an erect stance and have, in relation to the size of the pelvis, the biggest head and shoulders of any species, human fetuses are adapted to make birth possible.
The erect posture causes the weight of the abdominal contents to thrust on the pelvic floor, a complex structure which must not only support this weight but allow three channels to pass through it: the urethra, the vagina and the rectum. The relatively large head and shoulders require a specific sequence of manoeuvres to occur for the bony head and shoulders to pass through the bony ring of the pelvis. If these manoeuvres fail, the progress of labour is arrested. All changes in the soft tissues of the cervix and the birth canal are entirely dependent on the successful completion of these six maneuvers:
- Engagement of the fetal head in the transverse position. The baby is looking across the pelvis at one or other of the mother's hips.
- Descent and flexion of the fetal head
- Internal rotation. The fetal head rotates 90 degrees to the occipito-anterior position so that the baby's face is towards the mother's rectum.
- Delivery by extension. The fetal head passes out of the birth canal. Its head is tilted backwards so that its forehead leads the way through the vagina.
- Restitution. The fetal head turns through 45 degrees to restore its normal relationship with the shoulders, which are still at an angle.
- External rotation. The shoulders repeat the corkscrew movements of the head, which can be seen in the final movements of the fetal head.
The stages of normal human birth
Latent phase
The latent phase of labour may last many days and the contractions are an intensification of the Braxton-Hicks contractions that start around 26 weeks gestation. Cervical effacement occurs during the closing weeks of pregnancy and is usually complete or near complete, by the end of latent phase. Cervical effacement is the thinning and stretching of the cervix. The degree of cervical effacement may be felt during a vaginal examination. A 'long' cervix implies that not much has been taken into the lower segment, and vice versa for a 'short' cervix. Latent phase ends with the onset of active first stage; when the cervix is about 3 cm dilated.
First stage: contractions
The first stage of labor starts classically when the effaced (thinned) cervix is 3 cm dilated. There is variation in this point as some women may have active contractions prior to reaching this point, or they may reach this point without regular contractions. The onset of actual labor is defined when the cervix begins to progressively dilate. Rupture of the membranes, or a blood stained 'show' may or may not occur at around this stage.
Uterine muscles form opposing spirals from the top of the upper segment of the uterus to its junction with the lower segment. During effacement, the cervix becomes incorporated into the lower segment of the uterus. During a contraction, these muscles contract causing shortening of the upper segment and drawing upwards of the lower segment, in a gradual expulsive motion. This draws the cervix up over the baby's head. Full dilatation is reached when the cervix is the size of the baby's head; at around 10 cm dilation for a term baby.
The duration of labour varies widely, but active phase averages some 8 hours for women giving birth to their first child ("primiparae") and 4 hours for women who have already given birth ("multiparae").
Second stage: delivery
This stage begins when the cervix is fully dilated, and ends when the baby is finally delivered. At the beginning of the normal second stage, the head is fully engaged in the pelvis; the widest diameter of the head has successfully passed through the pelvic brim. Ideally it has successfully also passed below the interspinous diameter. This is the narrowest part of the pelvis. If these have been accomplished, all that will remain is for the fetal head to pass below the pubic arch and out through the introitus. This is assisted by the additional maternal efforts of "bearing down". The fetal head is seen to 'crown' as the labia part. At this point the woman may feel a burning or stinging sensation.
Delivery of the fetal head signals the successful completion of the fourth mechanism of labour (delivery by extension), and is followed by the fifth and sixth mechanisms (restitution and external rotation).
The second stage of labour will vary to some extent, depending on how successfully the preceding tasks have been accomplished.
Third stage: placenta
In this stage, the uterus expels the placenta (afterbirth). The placenta is usually delivered within 15-30 minutes of the baby being born. Maternal blood loss is limited by contraction of the uterus following delivery of the placenta. Normal blood loss is less than 600 mL.
The third stage can be managed either expectantly or actively. Expectant management (also known as physiological management) allows the placenta to be expelled without medical assistance. Breastfeeding soon after birth and massaging of the top of the uterus (the fundus) causes uterine contractions that encourage delivery of the placenta. Active management utilizes oxytocic agents and controlled cord traction. The oxytocic agents augment uterine muscular contraction and the cord traction assists with rapid delivery of the placenta.
A Cochrane database study suggests that blood loss and the risk of postpartum bleeding will be reduced in women offered active management of the third stage of labour. However, the use of ergometrine for active management was associated with nausea or vomiting and hypertension, and controlled cord traction requires the immediate clamping of the umbilical cord.
After the birth
Medical professionals typically recommend breastfeeding of the first milk, colostrum, to assist with uterine contraction to reduce postpartum bleeding/hemorrhage in the mother, and to pass antibodies, immunities and other benefits to the baby.
Many cultures feature initiation rites for newborns, such as naming ceremonies, baptism, and others.
Mothers are often allowed a period where they are relieved of their normal duties to recover from childbirth. The length of this period varies. In China it is 30 days and is referred to as "doing the month" or "sitting month" (see Postpartum period). In some other countries, taking time off from work to care for a newborn is called "maternity leave" or "parental leave" and can vary from a few days to several months.
Pain
Pain levels reported by labouring women vary widely. Pain levels seem to be influenced by fear and anxiety levels, experience with prior childbirth, cultural ideas of childbirth and pain, mobility during labour and the support given during labour. One study found that middle-eastern women, especially those with a low educational background, had more painful experiences during childbirth.
Pain is only one factor of many influencing women's experience with the process of childbirth. A systematic review of 137 studies found that personal expectations, the amount of support from caregivers, quality of the caregiver-patient relationship, and involvement in decisionmaking are more important in women's overall satisfaction with the experience of childbirth than are other factors such as age, socioeconomic status, ethnicity, preparation, physical environment, pain, immobility, or medical interventions.
Descriptions
Pain in contractions has been described as feeling like a very strong menstrual cramp. Midwives often encourage refraining from screaming but recommend moaning and grunting to relieve some pain. Crowning will feel like intense stretching and burning. Even women who show little reaction to labor pains often show a reaction to crowning.
Non-medical pain control
Some women prefer to avoid analgesic medication during childbirth. They still can try to alleviate labor pain using psychological preparation, education, massage, hypnosis, or water therapy in a tub or shower. Some women like to have someone to support them during labor and birth, such as the father of the baby, the woman's mother, a sister, a close friend, a partner or a doula. Some women deliver in a squatting or crawling position in order to more effectively push during the second stage and so that gravity can aid the descent of the baby through the birth canal.
The human body also has a chemical response to pain, by releasing endorphins. Endorphins are present before, during, and immediately after childbirth. Some homebirth advocates believe that this hormone can induce feelings of pleasure and euphoria during childbirth, reducing the risk of maternal depression some weeks later.
Water birth is an option chosen by some women for pain relief during labor and childbirth, and some studies have shown waterbirth in an uncomplicated pregnancy to reduce the need for analgesia, without evidence of increased risk to mother or newborn. Hot water tubs are available in many hospitals and birthing centres.
Meditation and mind medicine techniques are also used for pain control during labour and delivery. These techniques are used in conjunction with progressive muscle relaxation and many other forms of relaxation for the mind and body to aid in pain control for women during childbirth. One such technique is the use of hypnosis in childbirth.
A new mode of analgesia is sterile water injection placed just underneath the skin in the most painful spots during labor. A control trial in Iran of 0.5mL injections was conducted with normal saline which revealed a statistical superiority with water over saline.
Medical pain control
Different measures for pain control have varying degrees of success and side effects to the woman and her baby. In some countries of Europe, doctors commonly prescribe inhaled nitrous oxide gas for pain control; in the UK, midwives may use this gas without a doctor's prescription. Pethidine (with or without promethazine) may be used early in labour, as well as other opioids, but if given too close to birth there is a risk of respiratory depression in the infant.
Popular medical pain control in hospitals include the regional anesthetics epidural blocks, and spinal anaesthesia. Epidural analgesia is a generally safe and effective method of relieving pain in labour, but is associated with longer labour, more operative intervention (particularly instrument delivery), and increases in cost. One study found that the women receiving epidural analgesia had more fear before the administering of the epidural than those who did not receive it, but that they did not necessarily have more pain.
Medicine administered via epidural can cross the placenta and enter the bloodstream of the fetus. Epidural analgesia has no statistically significant impact on the risk of caesarean section, and does not appear to have an immediate effect on neonatal status as determined by Apgar scores.
Complications of birth
Birthing complications may be maternal or fetal, and long term or short term.
Labor complications
The second stage of labor may be delayed or lengthy due to:
- malpresentation of the fetal head (breech birth, face-first, or other)
- failure of descent of the fetal head through the pelvic brim or the interspinous diameter
- poor uterine contraction strength
- a big baby and a small pelvis
- shoulder dystocia
Secondary changes may be observed: swelling of the tissues, maternal exhaustion, fetal heart rate abnormalities. Left untreated, severe complications include death of mother and/or baby, and genitovaginal fistula. These are commonly seen in Third World countries where births are often unattended or attended by poorly trained community members.
Maternal complications
Vaginal birth injury with visible tears or episiotomies are common. Internal tissue tearing as well as nerve damage to the pelvic structures lead in a proportion of women to problems with prolapse, incontinence of stool or urine and sexual dysfunction. Fifteen percent of women become incontinent, to some degree, of stool or urine after normal delivery, this number rising considerably after these women reach menopause. Vaginal birth injury is a necessary, but not sufficient, cause of all non hysterectomy related prolapse in later life. Risk factors for significant vaginal birth injury include:
- a baby weighing more than 4 kilos (9 pounds)
- the use of forceps or vacuum for delivery. These markers are more likely to be signals for other abnormalities as forceps or vacuum are not used in normal deliveries.
- the need to repair large tears after delivery
Pelvic girdle pain. Hormones and enzymes work together to produce ligamentous relaxation and widening of the symphysis pubis during the last trimester of pregnancy. Most girdle pain occurs before birthing, and is known as diastasis of the pubic symphysis. Predisposing factors for girdle pain include maternal obesity.
Infection remains a major cause of mortality and morbidity in the developing world today. The work of Ignaz Semmelweis was seminal in the pathophysiology and treatment of puerperal fever and saved many lives.
Hemorrhage, or heavy blood loss, is still the leading cause of death of birthing mothers in the world today, especially in the developing world. Heavy blood loss leads to hypovolemic shock, insufficient perfusion of vital organs and death if not rapidly treated. Blood transfusion may be life saving. Rare sequelae include Hypopituitarism Sheehan's syndrome. The maternal mortality (MMR) rate varies from 9/100,000 live births in the US and Europe, to 900/100,000 live births in Sub-Saharan Africa.
Fetal complications
Mechanical fetal injury
Risk factors for fetal birth injury include fetal macrosomia (big baby), maternal obesity, the need for instrumental delivery, and an inexperienced attendant. Specific situations that can contribute to birth injury include breech presentation and shoulder dystocia. Most fetal birth injuries resolve without long term harm, but brachial plexus injury may lead to Erb's palsy.
Neonatal infection
Neonates are prone to infection in the first month of life. Some organisms such as S. agalactiae (Group B Streptococcus) or (GBS) are more prone to cause these occasionally fatal infections. Risk factors for GBS infection include:
- prematurity (birth prior to 37 weeks gestation)
- a sibling who has had a GBS infection
- prolonged labour or rupture of membranes
Untreated sexually transmitted infections are associated with congenital and perinatal infections in neonates, particularly in the areas where rates of infection remain high. The overall perinatal mortality rate associated with untreated syphilis, for example, approached 40%.
Neonatal death
Infant deaths (neonatal deaths from birth to 28 days, or perinatal deaths if including fetal deaths at 28 weeks gestation and later) are around 1% in modernized countries. The "natural" mortality rate of childbirth—where nothing is done to avert maternal death—has been estimated as being between 1,000 and 1,500 deaths per 100,000 births. (See main article: neonatal death, maternal death)
The most important factors affecting mortality in childbirth are adequate nutrition and access to quality medical care ("access" is affected both by the cost of available care, and distance from health services). "Medical care" in this context does not refer specifically to treatment in hospitals, but simply routine prenatal care and the presence, at the birth, of an attendant with birthing skills.
A 1983-1989 study by the Texas Department of Health highlighted the differences in neonatal mortality (NMR) between high risk and low risk pregnancies. NMR was 0.57% for doctor-attended high risk births, and 0.19% for low risk births attended by non-nurse midwives. Conversely, some studies demonstrate a higher perinatal mortality rate with assisted home births. Around 80% of pregnancies are low-risk. Factors that may make a birth high risk include prematurity, high blood pressure, gestational diabetes and a previous cesarean section.
Intrapartum asphyxia
The term Fetal distress is emotive and misleading. True intrapartum asphyxia is the impairment of oxygen to the brain and vital tissues during the progress of labour. This may exist in a pregnancy already impaired by maternal or fetal disease, or may rarely arise de novo in labour. True intrapartum asphyxia is not as common as previously believed, and is usually accompanied by multiple other symptoms during the immediate period after delivery. Monitoring might show up problems during birthing, but the interpretation and use of monitoring devices is complex and prone to misinterpretation.
Instrumental delivery (Forceps and Ventouse)
- The woman will have her legs supported in stirrups.
- If an anaesthetic is not already in place it will be given.
- Episiotomy might be needed.
- A Trial Forceps might be performed, which is abandoned in favor of a caesarean section if delivery is not optimal.
Twins and multiple births
Twins can be delivered vaginally. In some cases twin delivery is done in a larger delivery room or in theatre, just in case complications occur e.g.
- Both twins born vaginally - one comes normally but the other is breech and/or helped by a forceps/ventouse delivery
- One twin born vaginally and the other by caesarean section.
- If the twins are joined at any part of the body - called conjoined twins, delivery is mostly by caesarean section.
Variations
Being born in the caul
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 its membranes are easily broken and wiped away. In medieval times, and in some cultures still today, a caul was seen as a sign of good fortune for the baby, even giving the child psychic gifts such as clairvoyance, and in some cultures was seen as protection against drowning. 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, so babies are rarely born in the caul.
Professions associated with childbirth
Doulas are assistants who support mothers during pregnancy, labour, birth, and postpartum. They are not medical attendants; rather, they provide emotional support and non-medical pain relief for women during labour.
Maternal-fetal medicine specialists are experts in managing and treating high-risk pregnancy and delivery. Maternal-Fetal Medicine is a subspecialization in the field of obstetrics and gynecology. All maternal-fetal medicine specialists are doctors.
Midwives provide care to low-risk pregnant mothers. Midwives may be licensed and registered, or may be lay practitioners. Jurisdictions with legislated midwives will typically have a registering and disciplinary body, such as a College of Midwifery. Registered midwives are trained to assist a mother with labour and birth, either through direct-entry or nurse-midwifery programs. Lay midwives, who are usually not licensed or registered, typically gain experience through apprenticeship with other lay midwives.
Obstetricians provide care for normal and abnormal births and pathological labour conditions. Obstetricians are trained surgeons, so they can undertake surgical procedures relating to childbirth. Such procedures include cesarean sections, episiotomies, or assisted delivery. Most obstetricians also provide gynecological care, and may have a primary, well-woman, care element to their practices.
Obstetric nurses assist midwives, doctors, women, and babies prior to, during, and after the birth process, in the hospital system. Some midwives are also obstetric nurses. Obstetric nurses hold various certifications and typically undergo additional obstetric training in addition to standard nursing training.
Social and legal aspects
In most cultures, a person's age is now defined relative to their date of birth. Historically, in Europe age was once counted from baptism.
Some families view the placenta as a special part of birth, since it has been the child's life support for so many months. Some parents like to see and touch this organ. In some cultures, parents plant a tree along with the placenta on the child's first birthday. The placenta may be eaten by the newborn's family, ceremonially or otherwise (for nutrition; the great majority of animals in fact do this naturally).
The exact location in which childbirth takes place is an important factor in determining nationality, in particular for birth aboard aircraft and ships.
Psychological aspects
Childbirth can be an intense event and strong emotions, both positive and negative, can be brought to the surface.
While many women experience joy, relief, and elation upon the birth of their child, some women report symptoms compatible with post-traumatic stress disorder (PTSD) after birth. Between 70 and 80% of mothers in the United States report some feelings of sadness or "baby blues" after childbirth. Postpartum depression may develop in some women; about 10% of mothers in the United States are diagnosed with this condition. Abnormal and persistent fear of childbirth is known as tokophobia.
Preventive group therapy has proven effective as a prophylactic treatment for postpartum depression.
Childbirth is stressful for the infant. In addition to the normal stress of leaving the protected uterine environment, additional stresses associated with breech birth, such as asphyxiation, may affect the infant's brain.
Partner and other support
There is increasing evidence to show that the participation of the woman's partner in the birth leads to better birth and also post-birth outcomes, providing the partner does not exhibit excessive anxiety. Research also shows that when a labouring woman was supported by a female helper such as a family member or doula during labour, she had less need for chemical pain relief, the likelihood of caesarean section was reduced, use of forceps and other instrumental deliveries were reduced and there was a reduction in the length of labour and the baby had a higher Apgar score (Dellman 2004, Vernon 2006).
It has been found that fathers can have different roles during birth and that little is said about the conflicts between partners or partners and professionals. Among other findings were also: the interpretation of the presence of fathers during birth as a modern version of the anthropological couvade ritual to ease the woman's pain; the majority of fathers did not perceive any limitation to participate in their childbirth and upper generations did not play an important rule in the transmission of knowledge about birth to those fathers but the wives, feminine acquaintances and midwives.
The research was based, mainly, on in-depth interviews, where fathers described what was happening from their partner’s first signals of birth labour until the placenta delivery.
See also
External links
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