Breech birth: Wikis

  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

Breech birth
Classification and external resources

Frank breech, William Smellie, 1792
ICD-10 O32.1, O64.1, O80.1., O83.0, P03.0
ICD-9 652.1
DiseasesDB 1631
MedlinePlus 002060
eMedicine med/3272 emerg/868
MeSH D001946

A breech birth at the birth of a baby from a breech presentation. In the breech presentation the baby enters the birth canal with the buttocks or feet first as opposed to the normal head first presentation.

Contents

Etiology

Certain factors can encourage a breech presentation. Prematurity is likely the chief cause. Twenty five percent of fetuses are in the breech position at 32 weeks gestation; this drops to three percent at term. The increasing size of the fetus near term traps the fetus into the head down position normally. Pregnancies ending in preterm birth simply recruit more breeches before they can turn to head down. Factors predisposing to term breech presentation include:

It is postulated that the baby normally assumes a head down presentation because of the weight of the baby's head. As the mass of the fetal head is the same as that of the pelvis, it is more likely that the enlarging fetus is more and more restricted in its movements, and simply becomes entrapped. The shape of the uterus is a more likely determinant of the final fetal presentation as uterine shape anomalies are strong predictors of breech presentation and other malpresentations.

Epidemiology

Researchers generally cite a breech presentation frequency at term of 3-4%[2][3] at the onset of labour though some claim a frequency as high as 7%[4]. 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).

Categories

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 at term but relatively common with premature fetuses.
  • 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 extremely rare.

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 the same size in the term baby as the baby's head. Descent is thus as for the presenting fetal head and delay in descent is a cardinal sign of possible problems with the delivery of the head.

In order to begin the birth, internal rotation needs to occur. This happens when the mother's pelvic floor muscles cause the baby to turn so that it can be born with one hip directly in front of the other. At this point the baby is facing one of the mother's inner thighs. Then, the shoulders follow the same path as the hips did. At this time the baby usually turns to face the mother's back. Next occurs external rotation, which is when the shoulders emerge as the baby’s head enters the maternal pelvis. The combination of maternal muscle tone and uterine contractions cause the baby’s head to flex, chin to chest. Then the back of the baby's head emerges and finally the face.

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.[citation needed]

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.[citation needed]

Risks

Umbilical cord prolapse may occur, particularly in the complete, footling, or kneeling breech. This is caused by the lowermost parts of the baby not completely filling the space of the dilated cervix. When the waters break the 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 by the failure of the fetal head to negotiate the maternal midpelvis. At full term, the fetal bitrochanteric diameter (the distance between the outer points of the hips) is about the same as the biparietal diameter (the transverse diameter of the skull) - simply put the size of the hips are the same as the size of the head. The relatively larger buttocks dilate the cervix as effectively as the head does in the typical head-down presentation. In contrast, the relative head size of a preterm baby is greater than the fetal buttocks. If the baby is preterm, it may be 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 during a breech birth, it is important that the delivery of the aftercoming fetal head not be delayed. The head only just fits through the pelvis, and if the arm is extended alongside the head, delivery will not occur. If this occurs, the Løvset manoeuvre may be employed, or the arm may be manually brought to a position in front of the chest. The Løvset manoeuvre involves rotating the fetal body by holding the fetal pelvis. Twisting the body such that an arm trails behind the shoulder, it will tend to cross down over the face to a position where it can be reached by the obstetrician's finger, and brought to a position below the head. A similar rotation in the opposite direction is made to deliver the other arm. In order to present the smallest diameter (9.5 cm) to the pelvis, the baby’s head must be flexed (chin to chest). If the head is in a deflexed position, the risk of entrapment is increased. 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 rapid decompression of the baby's head. 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. The fetal head may be controlled by a special two handed grip call the Mariceau-Smellie-Veit manoeuvre or the elective application of forceps. This will be of value in controlling the rate of delivery of the head and reduce decompression. Related to potential head trauma, researchers have identified a relationship between breech birth and autism[5].

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 all variations of 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.

Injury may occur even if a birth attendant uses appropriate 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. This must be placed in perspective. It is this minority that determines the safety of the choice of vaginal delivery of the breech. A fetal death rate as low as 1% might be acceptable to some societies if a greater benefit could accrue. Take a country like the United States with a population of 300 million, and a 14.14/1000 birth rate, assume a 3% breech rate, and the aforementioned 1% mortality. This would result in an annual attributable death rate from breech delivery of 1,273 babies per year. Attributable death rate implies that the deaths occurred because of the selection of vaginal delivery and not from concurrent problems, such as congenital abnormalities or prematurity.

Intentional breech birth

As noted in the book Death and the Enlightenment by John McManners, it was mentioned that in 18th century France when the practice of an attending doctor was to keep the birth mother’s genital area obscured from view by a sheet, the doctor would sometimes display his “skill” by reaching under the sheet and turning the baby around so that a breech birth resulted—a very dangerous practice

Factors influencing the safety

  • 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 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.

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 the baby through the mother's abdomen. ECV has a success rate between 40 - 70% depending on practitioner.[6] The fetal heart is monitored after the turn attempt, usually in the context of an institutional protocol. Studies show that turning the baby at term (after 36 weeks) is effective in reducing the number of babies born in the breech position.[7] Complications from external cephalic version are rare. Studies have also shown that attempting to turn the baby prior to this point has no impact on the presentation at term.[8]

Using hypothetical scenarios, a small study in the Netherlands found that few obstetric practitioners would attempt ECV in the presence of oligohydramnios.[9] A case report of treating oligohydramnios with amnioinfusion, followed by ECV, was successful in turning the fetus.[10]

Various manoeuvres are suggested to assist spontaneous version of a breech presenting pregnancy. These include maternal positioning or other exercises. A study has shown that there is insufficient evidence as to the benefit of maternal positioning in reducing the incidence of breech presentation.[8]

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 increased by a Caesarean section, but still remains a rare complication in the First World. Third World statistics are dramatically different, and mortality is increased significantly. There is remote risk of injury to the mother's internal organs, injury to the baby, and severe hemorrhage requiring hysterectomy with resultant infertility. More commonly seen are problems with noncatastrophic bleeding, postoperative infection and wound healing problems. It should be added that the increase in maternal mortality rates could be slightly skewed due to the fact that Caesarean sections are often used during high-risk pregnancies and/or when mortality is already a strong possibility.

One large study has confirmed that elective cesarean section has lower risk to the fetus and a slightly increased risk to the mother, than planned vaginal delivery of the breech[11] however elements of the methodology used have undergone some criticism.[12][13]

The same birth injuries that can occur in vaginal breech birth may rarely occur in Caesarean breech delivery. A Caesarean breech delivery is still a breech delivery. However the soft tissues of the uterus and abdominal wall are more forgiving of breech delivery than the hard bony ring of the pelvis. 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 (uterine rupture). The presence of a uterine scar will be a risk factor for any subsequent pregnancies.

See also

References

  1. ^ Vendittelli F, Rivière O, Crenn-Hébert C, Rozan MA, Maria B, Jacquetin B (May 2008). "Is a breech presentation at term more frequent in women with a history of cesarean delivery?". Am. J. Obstet. Gynecol. 198 (5): 521.e1–6. doi:10.1016/j.ajog.2007.11.009. PMID 18241817. 
  2. ^ link not accessible: http://www.rwh.org.au/rwhcpg/maternity.cfm?doc_id=7857
  3. ^ Breech at term, Early and late consequences of mode of delivery, Lone Krebs, Danish Medical Bulletin - No. 4. November 2005. Vol. 52 Pages 234-52
  4. ^ Pregnancy, Breech Delivery, emedicine.com
  5. ^ Deborah Bilder, MD, Judith Pinborough-Zimmerman, PhD, Judith Miller, PhD and William McMahon, MD. "Prenatal, Perinatal, and Neonatal Factors Associated With Autism Spectrum Disorders." Pediatrics, 123(5), May 2009, pp. 1293-1300
  6. ^ Goer, Henci, Obstetric Myths versus Research Realities, Bergin and Garvey, London, 1995,
    • Oxorn, Harry. Human Labor and Birth, 5th edition. p. 111. Appleton & Lange, 1986.
  7. ^ External cephalic version for breech presentation at term Hofmeyr GJ, Kulier R, cochrane.org
  8. ^ a b Cephalic version by postural management for breech presentation Hofmeyr GJ, Kulier R, cochrane.org
  9. ^ Kok M, Van Der Steeg JW, Mol BW, Opmeer B, Van Der Post JA (2008). "Which factors play a role in clinical decision-making in external cephalic version?". Acta Obstet Gynecol Scand 87 (1): 31–5. doi:10.1080/00016340701728075. PMID 17957499. 
  10. ^ Buek JD, McVearry I, Lim E, Landy H, Afriyie-Gray A (June 2005). "Successful external cephalic version after amnioinfusion in a patient with preterm premature rupture of membranes". Am. J. Obstet. Gynecol. 192 (6): 2063–4. doi:10.1016/j.ajog.2004.07.057. PMID 15970899. 
  11. ^ Planned Caesarean section for term breech delivery, Hofmeyr GJ, Hannah ME, cochrane.org
  12. ^ When Research is Flawed: Planned Vaginal Birth versus Elective Cesarean for Breech Presentation [1]
  13. ^ Inappropriateness of randomised trials for complex phenomena [2]

External links








Got something to say? Make a comment.
Your name
Your email address
Message