What is a breech presentation Why may this be a problem during birth?

Special Clinical Circumstances and Risks: Preterm Breech, Hyperextended Head, and Footling Breech

The various categories of breech presentation clearly demonstrate dissimilar risks, and management plans might vary among these situations.The premature breech, the breech with a hyperextended head, and the footling breech are categories that have high rates of fetal morbidity or mortality. Complications associated with incomplete dilation and cephalic entrapment may be more frequent. For these three breech situations, in general, cesarean delivery appears to optimize fetal outcome and is therefore recommended.

As with term breech infants, the role of cesarean delivery for improving outcomes among low and very low birthweight breech infants is controversial. Although most deaths in those with a very low birthweight are due to prematurity or lethal anomalies, cesarean delivery has been shown by most authors to improve outcomes and decrease corrected perinatal mortality in this weight group compared with that in similar-sized vertex presentations.54–57 However, the improvements in outcome with cesarean delivery in the preterm breech may be more nuanced. A study of more than 8300 preterm singleton breech deliveries between 26 and 36 weeks’ gestation demonstrated no significant difference in overall perinatal mortality with cesarean versus vaginal delivery but did show improvements in mortality between 28 and 32 weeks, 1.7% versus 4.1% (aOR, 0.27; 95% CI, 0.10 to 0.77), and significant reductions in the composite of perinatal mortality or major morbidity, 5.9% versus 10.1% (aOR, 0.37; 95% CI, 0.20 to 0.68).56 Conversely, other observational studies including follow-up to 2 years after birth do not show clear improvements in outcomes with cesarean for the preterm breech.58–60 Other authors suggest that improved survival in these studies relates to improved neonatal care of the premature infant when compared with the outcomes of historic controls. However, when vaginal delivery of the preterm breech is chosen or is unavoidable, older studies have demonstrated reduced fetal morbidity and mortality when conduction anesthesia and Piper or Laufe forceps are used for delivery of the aftercoming head.

Preterm premature rupture of membranes (PPROM) is associated with prematurity and chorioamnionitis, both of which have been found to be independent risk factors for the development of cerebral palsy (CP). PPROM is associated with a high rate of malpresentation because of prematurity and decreased amniotic fluid. Knowing the association of chorioamnionitis with periventricular leukomalacia (PVL), a lesion found to precede development of CP in the premature neonate, Baud and colleagues61 correlated the mode of delivery with PVL and subsequent CP in breech preterm deliveries.The authors found that in the presence of chorioamnionitis, delivery by planned cesarean section was associated with a significant decrease in the incidence of PVL.

III. EFFECT ON PERINATAL OUTCOMES

Breech Presentation

Breech presentation occurs in approximately 3% to 4% of all deliveries. Its incidence decreases with advancing gestation. Weisman,186 using periodic radiographic examinations throughout pregnancy, found that 24% of fetuses were in breech presentation at 18 to 22 weeks' gestation, 8% at 28 to 30 weeks, 7% at 34 weeks, and 2.8% at 38 to 40 weeks. It is generally agreed that higher rates of neonatal morbidity and mortality are associated with breech presentation than with cephalic presentation at all gestational ages and birth weights.187 There is less agreement about what can be done to eliminate the risk for the infant who is in breech presentation at the time of delivery.

Part of the problem could be inherent in the etiology of breech presentation itself. The termbreech presentation is associated with fundal-cornual implantation of the placenta, which occurs in only 7% of all pregnancies.188 This association suggests that breech presentation often is related to a space problem in the uterus: Given the fundal-cornual placental implantation, an otherwise normal fetus finds it more comfortable to assume a breech position. Other studies have suggested that breech presentation could result from abnormal motor ability or diminished muscle tone in the fetus.

Braun and colleagues,189 reporting from a dysmorphology clinic, showed that the expected incidence of breech presentation (corrected for gestational age) was higher in fetuses with a variety of congenital disorders. Specifically, infants with neuromuscular disorders had an inordinately high rate of breech presentation at delivery.190,191 Furthermore, McBride and associates192 found that 100 children delivered in a breech presentation at term and studied at 5 years of age scored less well on motor skills than children delivered in cephalic presentations, regardless of the method by which the breech delivery was accomplished. These results suggest that, at least in some cases, the fetus remains in a breech position because it is less capable of movement within the uterus. If these concepts are accurate, the outcome for the fetus in a breech presentation could depend to a great extent on the reason for the breech position rather than the eventual mode of delivery.

Risks to the fetus inherent in breech presentation during labor and delivery include the following:

Prolapse of the umbilical cord (especially in the footling breech)

Trapping of the after-coming head by the incompletely dilated cervix (particularly in preterm infants weighing less than 1500 g and in CPD)

Trauma resulting from extension of the head or nuchal position of the arms

Breech presentation

Breech presentation occurs in 3%–4% of all term pregnancies. One in four fetuses will present as breech at some point in pregnancy, but by 34 weeks most of these will have shifted [41]. At 32 weeks, 7% of fetuses are breech. Breech deliveries are associated with serious risks of bleeding inside the baby’s skull, hypoxia, and injuries to the baby’s body especially the upper arm, brachial artery and spinal cord. For these reasons it is clearly desirable to have the baby turn to cephalic presentation for delivery. In many cases where the baby is breech at delivery, cesarean section is a common outcome. To turn the fetus, external cephalic version is the main medical option. This may be an uncomfortable procedure in which a midwife or physician manually encourages the fetus to turn. Due to the potential risk of complications, this procedure is generally done in the 37th week and carried out in a hospital while the baby is monitored. Acupuncture and moxibustion is another option for uncomplicated singleton pregnancies. Moxibustion is a method of stimulating acupuncture points with heat, using a herb called moxa that is shaped into a cigar. In the research to date, moxibustion has been used to turn the fetus starting at 34 weeks. Patients can be instructed to perform moxibustion at home. The moxa cigar is lit and held near the skin at the Bladder-67 point located on the outer edge of the little toe. The moxa is burned bilaterally for 20 minutes, once a day for 10 days [20].

A 2012 Cochrane review of 8 trials including 1346 women found limited evidence to support the use of moxibustion for correcting breech presentation. Moxibustion combined with acupuncture resulted in fewer noncephalic presentations at birth and fewer births by cesarean section compared with no treatment. Similarly, when combined with a postural technique, moxibustion was found to result in fewer noncephalic presentations at birth compared with the postural technique alone. Moxibustion on its own was not found to reduce the number of noncephalic presentations at birth. It was noted that the use of moxibustion may reduce the need for oxytocin before or during labor for women who had vaginal deliveries compared with no treatment [42]. With moxibustion as well as with acupuncture, dosage may be important. In the trials where moxibustion had no effect, it was used for a shorter period of time and there was less compliance of women completing the recommended course of treatment than in the trials that reported beneficial results. This is in line with the author’s clinical experience that adherence to the recommended treatment makes a big difference in outcome. In one case, the patient was told by her obstetrician that there was no way that the fetus could turn because there were large fibroids in the way. The patient was highly motivated and did moxibustion on herself every day twice a day. Toward the end of the 10 days, she felt a large movement in her belly and it was confirmed that the fetus had turned. She was later able to have an uncomplicated vaginal birth.

Criteria for Trial of Labor With a Planned Breech Delivery at Term

•

Gestational age >37 wk (proceed with caution in preterm delivery of the breech fetus; consider Maternal-Fetal Medicine consultation in these situations)

Estimated fetal weight, 2500 to 4000 g—recognizing inherent error in estimated fetal weight approximations; actual fetal weight may be substantially smaller or larger (proceed with caution in fetuses weighing 1500 to 2500 g; consider Maternal-Fetal Medicine consultation in these situations)

Adequate pelvis

Flexed fetal head

Frank or complete breech preferred if planning induction, although in active spontaneous unplanned labor, footling breech can be delivered safely if no cord prolapse

No known fetal anomalies

Normal amniotic fluid index (consider at minimum presence of mean vertical pocket >2 cm)

Bedside availability of anesthesia and capability for immediate cesarean section (consider epidural placement; consider delivery in operating room in the event of need for emergent cesarean section)

Informed consent

Obstetrician trained in vaginal breech delivery

Breech presentation.

A true breech presentation implies that the fetus is in posterior presentation in a dorsosacral position with both back limbs retained beneath the fetal body. Breech fetuses are handled similar to those with carpal flexion by straightening each flexed hindlimb. In these cases, the rear quarters of the fetus and the tail are felt on vaginal examination. If the veterinarian’s hands are small enough, manual correction of the dystocia may be possible. The fetus should be repelled or pushed cranially and to one side. Raising the female’s hindquarters can make this maneuver much easier. The clinician should then try to pull a hock back into the pelvic canal. After one hock is in the pelvis, it should be rotated laterally in relation to the long axis of the fetus while the foot is pulled ventrally and medially out through the vulva. The veterinarian should take care not to injure the female’s vagina with the fetal hooves. The same procedure is then repeated on the contralateral limb, and the fetus is extracted.

Breech Delivery

Management of breech presentation has undergone a significant shift in the last 15 years. The Term Breech Trial (TBT), published in 2000, was a large randomized study comparing elective cesarean at term to vaginal delivery.83 The trial was stopped before the full sample was achieved due to an excess in the composite morbidity-mortality outcome in the trial of labor group (elective cesarean delivery (1.6%), trial of vaginal delivery (5.1%) (RR 0.33, 95% CI 0.19–0.56). Planned cesarean birth quickly became the new standard for care and management of breech birth.84 Criticism of the TBT began to surface soon after its publication, with suggestions that the selection criteria for the trial were flawed, did not account for practice variability between participating centers, and that most of the cases of neonatal death and morbidity included in the study could not be attributed to the mode of delivery.85–87

‘PREMODA’ was an observational study of the method of delivery of term breech pregnancies conducted in France and in Belgium, 2 countries where vaginal breech delivery had remained a part of routine obstetrical practice. Women being considered for a trial of vaginal delivery were required to meet standard pre-specified criteria. In this study, planned vaginal breech delivery of the singleton term fetus was the safest option for most women.88 They found no statistically significant differences with respect to occurrence of a composite adverse neonatal outcome between planned vaginal and elective cesarean delivery for groups (OR 1.40, 95% CI 0.80–2.23).87 Other studies have found similar conclusions: given a specific set of clinical selection criteria, vaginal breech delivery at term was a safe option.89 In a further follow-up study, the authors of the original term breech trial found no statistically significant differences in maternal and neonatal outcome 2 years after birth.90,91

In light of these results, ACOG, the Royal College of Obstetricians and Gynecologists, and the SOGC have revised their guidelines regarding management of term breech presentation, and now consider planned vaginal delivery a reasonable option, providing that specific selection criteria are met, including the presence at delivery of an obstetrician experienced in vaginal breech delivery.92,93

Genesis

The frequency of singleton breech presentation at term is 3.1% and rises to 6.2% when multiple births are included.1–4 Breech presentation is an important cause of deformation, and fully one third of all deformations occur in babies who have been in breech presentation (Fig. 42‐1).2 Because 2% of newborns have deformations, this indicates that 0.6% of neonates have one or more deformations due to breech presentation; therefore, this topic will be given extensive coverage. Among infants born with deformations, 32% were in breech presentation (versus 5% to 6% of normally formed infants), and 23% of malformed infants were also in breech presentation.3 Among 142 infants with spina bifida, 38% were in breech presentation, and 68% of these infants had lower‐extremity weakness or paralysis. Among those infants with paralyzed legs, 93% manifested breech presentation; thus, breech presentation becomes more likely with fetal inability to power the legs.4 Numerous fetal and maternal factors can lead to breech presentation and thereby increase the risk for adverse outcomes. Some of these factors include prematurity (25% breech), twinning (34% breech), oligohydramnios due to chronic leakage (64% breech), uterine malformations, placenta previa, maternal hypertension, and fetal malformations.

Breech presentation is more common in the primigravida, especially the older primigravida, presumably because of the shape of the uterus and the reduced space for fetal and uterine growth. The spatial restrictions associated with twinning also increase the likelihood of breech presentation, especially for the second‐born. The prematurely born baby is also less likely to have shifted into the vertex birth position, and prematurity is more common with multiple births. Unless there is oligohydramnios or twinning, the premature fetus in breech presentation generally does not have associated deformations because there has not been sufficient constraint to cause molding. Furthermore, breech presentation can be considered normal with prematurity because at 32 weeks of gestation, 25% of all fetuses are in breech presentation; after this time, the majority of fetuses shift into vertex presentation.3 Any situation that causes oligohydramnios, whether it be chronic leakage of amniotic fluid or lack of urine flow into the amniotic space, will restrict movement and greatly increase the chance of the fetus being in breech presentation. Alterations in the size and shape of the uterine cavity may also increase the frequency of breech presentation. This may be secondary to uterine structural anomalies or myomas. The implantation and placement of the placenta may also be a factor, as 66% of placentas in breech delivery implant in the cornual‐fundal region (versus 4% of vertex presentations), whereas in 76% of vertex presentations, the placenta implants on the midwall of the uterus (versus 4% of breech presentations).3

Although the best mode of delivery for infants in breech presentation is controversial, most studies suggest that the risk for neonatal morbidity and mortality is increased when infants in breech presentation are delivered vaginally as opposed to via cesarean section.3,5–8 Traumatic injuries following vaginal delivery of breech infants can include fractures and dislocations, brachial plexus injuries, facial nerve injuries, cerebral hemorrhages, bruising with hyperbilirubinemia, cervical cord injuries, cord prolapse, birth asphyxia, and testicular trauma.2–5 In most large series, these types of injuries occur less frequently with cesarean delivery, but in some recent series using modern delivery methods, the rate of such injuries is similar in planned vaginal breech delivery compared with elective cesarean section. This has led some authors to suggest that with a normal pelvis and normal term birth weight, assisted vaginal breech delivery by an experienced obstetrician may be as safe as cesarean section delivery, which increases the risk of maternal morbidity in most large studies.9–11 Because of the risk of cervical cord injuries with vaginal delivery, most studies have relegated breech infants with hyperextended heads for automatic cesarean section.5 Trials of vaginal delivery have succeeded in 60% to 70% of patients, without significant differences in outcome measures for primiparas versus multiparas or for frank versus non‐frank breech presentations.9,11 In North America, 70% to 80% of all women with breech presentation deliver by cesarean section (with similar trends observed in other parts of the world), so obstetric resident training experience with vaginal breech deliveries may be insufficient to guarantee sufficient expertise.12

Breech presentation shows a familial tendency, and 22% of multiparous women delivering a breech infant had previously experienced a breech delivery.4 If the first infant in a family is breech‐born, there is a 9.4% chance the second child will be breech‐born; whereas if the first child is vertex, there is only a 2.4% chance the second will be breech (this being the background risk for breech delivery).13 Women with recurring breech presentation have a lower risk of adverse perinatal outcome, possibly due to increased attention to perinatal care.8 The familial tendency toward breech deliveries may be related to inherited uterine structural characteristics, or it may be a consequence of a genetic neuromuscular or fetal malformation syndrome such as myotonic dystrophy. Presumably, the lower risk of adverse perinatal outcome relates to detection of maternal anatomic abnormalities (or fetal genetic abnormalities) that might result in closer follow‐up during subsequent pregnancies.

In about 70% of fetuses in breech presentation, the legs are extended in front of the abdomen (Fig. 42‐2).4 Once the movements of the fetus become limited by extension of the legs in front of the abdomen, the fetus has less chance of extricating itself from the breech presentation,13 and Dunn has used the analogy of the “folding body press” wrestling hold.4 Once a wrestler has an opponent in a position with the legs in front of the abdomen, there is little the opponent can do to escape. Breech presentation with the hips flexed and knees extended is termed frank breech (see Figs. 42‐2 and 42‐3, A and D). When the hips and knees are flexed, it is called complete breech (Fig. 42‐3, C), and when the hips and knees are extended, it is referred to as to the footling breech, as depicted in Fig. 42‐3, B. With modern methods of delivery, the particular type of breech presentation appears to have no significant effect on adverse outcomes associated with the mode of delivery, despite that cord prolapse occurs much less frequently with frank breech presentation (0.4%) versus complete breech (4%–10.5%) or footling breech presentation (15%–28.5%).11

REASONS FOR BREECH PRESENTATION

In most cases a persistent breech position is nonpathologic in origin, being a random occurrence, or a combination of the dynamics between the maternal pelvic and fetal head shapes. Breech presentation itself presents little risk to the fetus. In some cases, however, persistent breech position is the result of a maternal, fetal, or placental problem. Maternal factors that may contribute to breech presentation include uterine abnormalities that change the normal shape of the uterus, for example, bicornate uterus or uterine fibroids; multiparity that leads to uterine and abdominal wall laxity, changing the shape of the uterus; and a deformed or contracted maternal pelvis. Placental abnormalities, for example, placenta previa, which prevent the fetal head from properly entering the pelvis can contribute to breech position, as can amniotic fluid volume abnormalities (polyhydramnios, oligohydramnios). Any factors that alter either the normal fetal shape or normal fetal mobility can contribute to breech presentation, and include fetal anomalies (e.g., anencephaly, hydrocephaly), multiple pregnancy (i.e., twins), short umbilical cord, and fetal demise. Previous breech birth is considered a risk factor for breech presentation in subsequent pregnancies.

Special Clinical Circumstances and Risks: Preterm Breech, Hyperextended Head, and Footling Breech

The various categories of breech presentation clearly demonstrate dissimilar risks, and management plans might vary among these situations. The premature breech, the breech with a hyperextended head, and the footling breech are categories that have high rates of fetal morbidity or mortality. Complications associated with incomplete dilation and cephalic entrapment may be more frequent. For these three breech situations, in general, cesarean delivery appears to optimize fetal outcome and is therefore recommended.

Low birthweight (<2500 g) is a confounding factor in about one third of all breech presentations.17 Whereas the benefit of cesarean delivery for the breech infant weighing 1500 to 2500 g remains controversial,13 some studies have shown improved survival with cesarean delivery in the 1000- to 1500-g weight group.40,41 A multicenter study of long-term outcomes of vaginally delivered infants at 26 to 31 weeks' gestation found no differences in rates of death or developmental disability within 2 years of follow-up.42 Traumatic morbidity is reportedly decreased in both weight groups by the use of cesarean delivery, including a lower rate of both intraventricular and periventricular hemorrhage. Although some advocate a trial of labor in the frank breech infant weighing over 1500 g, others recommend labor only when the infant exceeds 2000 grams. Proportionately fewer frank breech presentations occur in the low-birthweight group. In fact, most infants who weigh less than 1500 g and present as a breech are footling breeches. Although most deaths in those with a very low birthweight are due to prematurity or lethal anomalies, cesarean delivery has been shown by some to decrease corrected perinatal mortality in this weight group compared with that in similar-sized vertex presentations.43 Other authors suggest that improved survival in these studies relates to improved neonatal care of the premature infant when compared with the outcomes of historic controls. How­ever, when vaginal delivery of the preterm breech is chosen or is unavoidable, older studies have demonstrated reduced fetal morbidity and mortality when conduction anesthesia and forceps for the delivery of the aftercoming head are used; neither are commonplace in modern obstetrics. A study of neonates at 26 to 29 weeks 6 days gestational age born by planned breech versus planned cesarean delivery showed no difference in mortality rate.44 Although in this study, premature rupture of the membranes (PROM) at a gestational age less than 24 weeks, head entrapment, and a gestational age between 26 to 27 weeks 6 days were all independently associated with neonatal death.

Preterm premature rupture of the fetal membranes (PPROM) is associated with prematurity and chorioamnionitis, both of which have been found to be independent risk factors for the development of cerebral palsy (CP). PPROM is associated with a high rate of malpresentation because of prematurity and decreased amniotic fluid. Knowing the association of chorioamnionitis with periventricular leukomalacia (PVL), a lesion found to precede development of CP in the premature neonate, Baud and colleagues45 correlated the mode of delivery with PVL and subsequent CP in breech preterm deliveries. The authors found that in the presence of chorioamnionitis, delivery by planned cesarean section was associated with a dramatic decrease in the incidence of PVL.

Hyperextension of the fetal head during vaginal breech delivery has been consistently associated with a high (21%) risk of spinal cord injury. It is important to differentiate simple deflexion of the head from clear hyperextension, given that Ballas and colleagues demonstrated that simple deflexion carries no excess risk. Deflexion of the fetal vertex, as opposed to hyperextension, is similar to the relationship between the occipitofrontal cranial plane and the axis of the fetal cervical spine illustrated in Figure 17-5. Often, as labor progresses, spontaneous flexion will occur in response to fundal forces.

Finally, the footling breech carries a prohibitively high (16% to 19%) risk of cord prolapse during labor. In many cases, cord prolapse manifests only late in labor, after commitment to vaginal delivery may have been made. Cord prolapse necessitates prompt cesarean delivery. Furthermore, the footling breech is a poor cervical dilator, and cephalic entrapment becomes more likely.