Breech birth
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A breech birth (also known as breech presentation) refers to the position of the baby in the uterus such that it will be delivered buttocks first as opposed to the normal head first position.
[edit] Etiology
Certain factors can encourage a breech presentation. These include multiple pregnancy (twins, triplets or more), excessive amounts of amniotic fluid, hydrocephaly, anencephaly, very short umbilical cord, and some uterine abnormalities. Babies with congenital abnormalities are more likely to be breech.
[edit] Epidemiology
Researchers generally cite a breech presentation frequency at term of 3-4%[1][2] at the onset of labour though some claim a frequency as high as 7%[3]. When labour is premature, the incidence of breech presentation is higher. At 28 weeks' gestation 25% of babies are breech, and the percentage decreases approaching term (40 weeks' gestation). This is because the weight of the baby's head encourages a head down position, and because as the baby grows and takes up more room in the uterus, it is less able to move about freely.
[edit] Categories of breech presentation
There are four main categories of breech births:
- Frank breech - the baby's bottom comes first, and his or her legs are flexed at the hip and extended at the knees (with feet near the ears). 65-70% of breech babies are in the frank breech position.
- Complete breech - the baby's hips and knees are flexed so that the baby is sitting crosslegged, with feet beside the bottom.
- Footling breech - one or both feet come first, with the bottom at a higher position. This is rare.
- Kneeling breech - the baby is in a kneeling position, with one or both legs extended at the hips and flexed at the knees. This is rare.
[edit] Process of breech birth
As in labour with a baby in a normal head-down position, uterine contractions typically occur at regular intervals and gradually cause the cervix to become thinner and to open. In the more common breech presentations, the baby’s bottom (rather than feet or knees) is what is first to descend through the maternal pelvis and emerge from the vagina.
At the beginning of labour, the baby is generally in an oblique position, facing either the right or left side of the mother's back. As the baby's bottom is a less efficient dilator than the head, the buttocks may remain high until late in labor. In order for the baby to pass through the mother’s pelvis, there is flexion at the side of the waist, so that one hip becomes the leading part.
The mother's pelvic floor muscles cause the baby to turn slightly so that the hips are born, usually one at a time, with the baby facing one of the mother's inner thighs. At this time the baby's shoulders are entering the mother's pelvis, and the baby's position adjusts again so that they are obliquely facing the mother's back.
The shoulders emerge as the baby’s head is entering the pelvis. The combination of maternal muscle tone and uterine contractions cause the baby’s head to flex, chin to chest. The baby's position changes again so that they are facing the mother's sacrum. Then the face emerges, and finally the back of the baby's head.
Due to the increased pressure during labour and birth, it is normal for the baby's leading hip to be bruised and genitalia to be swollen; this usually resolves shortly after birth.
Babies who assumed the frank breech position in utero may continue to hold their legs in this position for some days after birth - this is normal.
[edit] Risks of breech birth
Umbilical cord prolapse may occur, particularly in the complete, footling, or kneeling breech. This is caused by the lowermost parts of the baby do not completely filling the space of the dilated cervix. When the waters break amniotic sac, it is possible for the umbilical cord to drop down and become compressed. This complication severely diminishes oxygen flow to the baby and the baby must be delivered immediately (usually by Caesarean section) so that he or she can breathe. If there is a delay in delivery, the brain can be damaged. Among full-term, head down babies, cord prolapse is quite rare, occurring in 0.4 percent. Among frank breech babies the incidence is 0.5 percent, among complete breeches 4-6 percent, and among footling breeches 15-18 percent.
Head entrapment is caused the failure of the buttocks to dilate the cervix as effectively as the head does in the typical head-down presentation. It is possible for the baby’s body to emerge while the cervix has not dilated enough for the head to emerge. Because the umbilical cord—the baby’s oxygen supply—is significantly compressed while the head is in the pelvis, it is important for delivery to be accomplished quickly once the head is in the pelvis. If one of the baby’s arms is next to the head, the attendant may have to draw down the arm so that there is enough room for the head to be born. In order to have the smallest diameter (10 cm) moving through the pelvis, the baby’s head must be flexed (chin to chest). If the head is in a deflexed position, the head may become entrapped. Uterine contractions and maternal muscle tone encourage the head to flex. If the birth attendant pulls on the baby’s body, this action may deflex the head.
Oxygen deprivation may occur from either cord prolapse or prolonged compression of the cord during birth, as in head entrapment. If oxygen deprivation is prolonged, it may cause permanent neurological damage or death.
Injury to the brain and skull may occur due to the rapid passage of the baby's head through the mother's pelvis. This causes compression and decompression of the baby's head to occur within a few minutes. In contrast, a baby going through labor in the head-down position usually experiences gradual molding (temporary reshaping of the skull) over the course of a few hours. This sudden compression and decompression in breech birth may cause no problems at all, but it can injure the brain. This injury is more likely in preterm babies.
Damage resulting from rough handling during delivery may occur if a birth attendant uses inappropriate interventions during labour. A majority of full-term term frank breech babies would be born without problems even without assistance. However, in a minority of cases, expert assistance is needed for the baby to be born safely. If the doctor, midwife, or unskilled attendant intervenes when action is not necessary or does not use proper maneuvers to resolve complications, permanent damage may occur. For instance, pulling on the baby can cause deflexion of the head or entrapment of one or both arms, which can delay completion of delivery long enough to cause damage or death from oxygen deprivation. Squeezing the baby’s abdomen can damage internal organs. Positioning the baby incorrectly while using forceps to deliver the aftercoming head can damage the spine or spinal cord. It is important for the birth attendant to be knowledgeable, skilled, and experienced with breech birth. In the United States, because Cesarean section is increasingly being used for breech babies, fewer and fewer birth attendants are developing these skills.
Even with early expert intervention, there is a small possibility of serious complications or even death.
[edit] Factors influencing the safety of breech birth
- Type of breech presentation - the frank breech has the most favorable outcomes in vaginal birth, with many studies suggesting no difference in outcome compared to head down babies. (Some studies, however, find that planned caesarean sections for all breech babies improve outcome. The difference may rest in part on the skill of the doctors who delivered babies in different studies.) Complete breech presentation is the next most favorable position, but these babies sometimes shift and become footling breeches during labour. Footling and kneeling breeches have a higher risk of cord prolapse and head entrapment.
- Parity - Parity refers to the number of times a woman has given birth before. If a woman has given birth vaginally, her pelvis has "proven" it is big enough to allow a baby of that baby's size to pass through it. However, a head-down baby's head often molds (shifts its shape to fit the maternal pelvis) and so may present a smaller diameter than the same size baby born breech. Research on the issue has been contradictory as far as whether vaginal breech birth is safer when the mother has given birth before, or not.
- Fetal size in relation to maternal pelvic size - If the mother's pelvis is roomy and the baby is not large, this is favorable for vaginal breech delivery. However, prenatal estimates of the size of the baby and the size of the pelvis are fairly unreliable.
- Hyperextension of the fetal head - this can be evaluated with ultrasound. Less than 5% of breech babies have their heads in the "star gazing" position, face looking straight upwards and the back of the head resting against the back of the neck. Caesarean delivery is absolutely necessary, because vaginal birth with the baby's head in this position confers a high risk of spinal cord trauma and death.
- Maturity of the Baby Premature babies appear to be at higher risk of complications if delivered vaginally than if delivered by caesarean section.
- Progress of Labour - A spontaneous, normally progressing, straightforward labour requiring no intervention is a favourable sign.
- Second twins - If a first twin is born head down and the second twin is breech, the chances are good that the second twin can have a safe breech birth.
- Birth attendant's skill (and experience with breech birth) - The skill of the doctor or midwife and the number of breech births previously assisted is of crucial importance. Many of the dangers in vaginal birth for breech babies come from mistakes made by birth attendants.
[edit] Diagnosis of breech presentation
Early in pregnancy the baby changes position freely and frequently. By 28 weeks gestation, most babies are in the "head-down" position most of the time. The mother carrying a breech fetus often feels that there is a hard, round part of the baby under her ribs; she feels kicking in the lower part of her uterus or around her umbilicus rather than at the top of her uterus; she may feel the baby hiccupping just under her ribs and may report that something feels different compared to previous pregnancies.
The midwife or doctor can usually feel the baby's position by palpating the mother's abdomen (Leopold’s maneuvers). The baby's head and bottom may feel similar, but if the head is in the top of the uterus, it can be wiggled without moving the baby’s whole body.
Listening to the baby’s heartbeat with a stethoscope or fetoscope can also indicate whether the baby is breech. Hearing the heartbeat above the mother's umbilicus suggests a breech presentation. Listening to the fetal heartbeat with an ultrasound-based electronic device does not give the same information because it can pick up the fetal heartbeat from many different locations. If the baby is breech, the mother's uterus may measure larger than expected for how far along the pregnancy has progressed. If it is late in pregnancy and the cervix has opened slightly, the midwife or doctor may be able to confirm head-down presentation by feeling the sagittal suture than runs between the baby's unfused skull bones. An ultrasound scan can visualize the fetus and reveal its position.
[edit] Turning the baby to avoid breech birth
There are many methods which have been attempted with the aim of turning breech babies, with varying degrees of success:
- External cephalic version where a midwife or doctor turns the baby by manipulating her/him through the mother's abdomen, while listening to the heartbeat to be sure the umbilical cord is not compressed. ECV has a success rate between 40 - 70% depending on practitioner (Goer, 1995, 111)
- Swimming
- Maternal positioning, for a few minutes several times a day, to give the baby more room and encourage turning (including the knee-chest position, the all-fours position, crawling, and lying down with several pillows under the mother's buttocks to elevate her pelvis)
[edit] Breech birth versus Caesarean section
Caesarean section is the most common way to deliver a breech baby in the USA, Australia, and Great Britain. Like any major surgery, it involves risks. Maternal mortality is significantly increased by a Caesarean section. There is risk of injury to the mother's internal organs, injury to the baby, and severe hemorrhage requiring hysterectomy with resultant infertility.
The same birth injuries that can occur in vaginal breech birth can also occur in caesarean breech delivery because of difficulty extracting the baby. If a caesarean is scheduled in advance (rather than waiting for the onset of labor) there is a risk of accidentally delivering the baby too early, so that the baby might have complications of prematurity. The mother's subsequent pregnancies will be riskier than they would be after a vaginal birth (risk of unexplained stillbirth, uterine rupture, placental abnormalities). If the incision into the uterus has to be enlarged or made into a "T" shape, the risk of uterine rupture in future pregnancies will be significant, with its risk of damage or death to both mother and future baby.
Normal vaginal birth should only be attempted if the midwife or doctor believes that the baby is in a favourable breech position.
[edit] See also
[edit] External links
- Photographs showing vaginal births of a breech babies..
- Breech birth controversies in Great Britain.
[edit] References
- Banks, Maggie. Breech Birth Woman Wise. Birthspirit Books, 1998.
- Fraser, Diane and Cooper, Margaret (Eds). Myles Textbook for Midwives, 14th edition. Churchill Livingstone, 2003.
- Frye, Anne. Holistic Midwifery: A Comprehensive Textbook for Midwives in Homebirth Practice, Vol I, Care During Pregnancy. Labrys Press, 1995.
- Gabbe, Steven; Niebyl, Jennifer; and Simpson, Joe Leigh (Eds). Obstetrics: Normal and Problem Pregnancies, 4th edition. Churchill Livingstone, 2002.
- Goer, Henci, Obstetric Myths versus Research Realities, Bergin and Garvey, London, 1995,
- Oxorn, Harry. Human Labor and Birth, 5th edition. Appleton & Lange, 1986.
- Vernon, David ed. Having a Great Birth in Australia Australian College of Midwives, Canberra, 2005 ISBN 0-9751674-3-X
- Waites, Benna. Breech Birth. Free Association Books, 2003
