Other investigators advocate cesarean delivery for both members of a cephalic-noncephalic twin pair (Armson, 2006; Hofmann, 2012). Yang and coworkers (2005a,b) studied 15,185 cephalicnoncephalic twin pairs. he risks of asphyxia-related neonatal deaths and morbidity were higher in the group in which both twins were delivered vaginally compared with the group in which both twins underwent cesarean delivery.
To add insight into the clinical complexities just discussed, a randomized trial was designed by the Twin Birth Study Collaborative Group from Canada. he study results described by Barrett and associates (2013) included 2804 women carrying a presumed diamnionic twin pregnancy with the irst fetus presenting cephalic. Women were randomly assigned between 32 and 38 weeks' gestation to planned cesarean or vaginal delivery. The time from randomization to delivery-12.4 versus 13.3 days, the mean gestational age at delivery-36.7 versus 36.8 weeks, and use of regional analgesia-92 versus 87 percent, were similar in both groups. Salient maternal and perinatal outcomes are shown in Table 45-3. No significant diferences in outcomes were noted between the two groups of women. Although risks to mother or fetuses with planned vaginal delivery in these circumstances were not increased, Greene (2013) posited that this trial would have only modest efects on the cesarean delivery rate of women with twins.
Breech Presentation of First Twin
Problems with the first twin presenting as a breech are similar to those encountered with a singleton breech fetus. hus, major diiculties may develop in the following settings. First, the fetus may be large, and the aftercoming head is larger than the birth canal. Second, the fetal body can be small, and delivery of the extremities and trunk through an inadequately efaced and dilated cervix causes the relatively larger head to become trapped above the cervix. his is more likely when there is significant disproportion between the head and body. Examples are preterm or growth-restricted fetuses or those with
Serious morbidity 1.3% 1.3% Possible 0.5% 0.4%
Intubation 1.0% 0.6% alncludes coma; stupor; hyperalert, drowsy or lethargic; or ::2 seizu res.
Data from Barrett, 20ln3.
macrocephaly from hydrocephaly. Last, umbilical cord prolapse is an ever-present risk.
If these problems are anticipated or identiied, cesarean delivery is often preferred with a viable-sized fetus. But even without these problems, many obstetricians perform cesarean delivery if the irst twin presents as breech. This is despite data that support the safety of vaginal delivery. Specifically, Blickstein and associates (2000) reported experiences from 13 European centers with 613 twin pairs and the first twin presenting breech. Vaginal delivery was attempted in 373 of these cases and was successful in 64 percent. Cesarean delivery of the second twin was done in 2.4 percent. here was no diference in the rate of 5-minute Apgar scores <7 or of mortality in breech-presenting first twins who weighed at least 1500 g. Details of techniques for delivery of a breech presentation are described in Chapter 28 (p. 544).
Twin fetuses may become locked together during delivery if the irst presents breech and the second cephalic. As the breech of the irst twin descends through the birth canal, the chin locks between the neck and chin of the second cephalic-presenting cotwin. This phenomenon is rare, and Cohen and coworkers (1965) described it only once in 817 twin gestations. Cesarean delivery should be considered when the potential for locking is identiied.
• Vaginal Delivery of the Second Twin