From their guidelines, the American College of Obstetricians and Gynecologists (2016) recommends delivery at 38 weeks for uncomplicated dichorionic twin pregnancies. Women with uncomplicated monochorionic diamnionic twin pregnancies can undergo delivery between 34 and weeks. And, for women with monoamnionic twin pregnancies, delivery is recommended at 32 to 34 weeks. At Parkland Hospital, we generally follow these recommendations but do not routinely deliver monochorionic diamnionic twin pregnancies before 37 weeks unless another obstetrical indication develops.
• Evaluation of Fetal Presentation
In addition to the standard preparations for the conduct oflabor and delivery discussed in Chapter 22, there are special considerations for women with a multifetal pregnancy. First, the positions and presentations of fetuses are best confirmed sonographically. Although any possible combination of positions may be encountered, those most common at admission for delivery are cephalic-cephalic, cephalic-breech, and cephalic-transverse. At Parkland Hospital between 2008 and 2013, 71 percent of twin pregnancies had a cephalic presentation of the irst fetus at the time of admission to labor and delivery. Importantly, with perhaps the exception of cephalic-cephalic presentations, these are all unstable before and during labor and delivery. Accordingly, compound, face, brow, and footling breech presentations are relatively common, and even more so if fetuses are small, amnionic luid is excessive, or maternal parity is high. Cord prolapse is also frequent in these circumstances.
After this initial evaluation, if active labor is conirmed, then a decision is made to attempt vaginal delivery or to proceed with cesarean delivery. The latter is usually chosen because of fetal presentations. In general, cephalic presentation of the irst fetus in a laboring woman with twins may be considered for vaginal delivery (American College of Obstetricians and Gynecologists, 2016). The proportion of women undergoing an attempted vaginal delivery varies greatly depending on the skills of the delivering physician (de Castro, 2016; Easter, 2017; Schmitz, 2017). Still, the cesarean delivery rate is high. For example, of the 547 women with the irst twin presenting cephalic who were admitted to Parkland Hospital during 5 years, only 32 percent were delivered spontaneously. And, the overall cesarean delivery rate in twin pregnancies during those years was 77 percent. Notably, 5 percent of cesareans performed were for emergent delivery of the second twin following vaginal delivery of the first twin. The desire to avoid this obstetrical dilemma has contributed to the rising cesarean delivery rate in twin pregnancies across the United States (Antsalis, 2013).
After a comparison of 891 twins with more than 100,000 singleton pregnancies included in the Consortium of Safe Labor, Leftwich and colleagues (2013) concluded that active labor progressed more slowly in both nulliparas and multiparas with twins. Provided women with twins meet all criteria for oxytocin administration, it may be used as described in Chapter 26 (p. 509). Wolfe and associates (2013) evaluated the success of labor induction and concluded that oxytocin alone or in combination with cervical ripening can safely be used in twin gestations. Taylor and coworkers (2012) reported similar results. Conversely, Razavi and colleagues (2017) found that maternal morbidity was increased with labor induction. In an analysis of twin births in the United States, induction rates of twin pregnancies have decreased from a maximum of 13.8 percent in 1999 to 9.9 percent in 2008 (Lee, 2011). Generally, at Parkland Hospital we do not induce or augment labor in women with a multifetal gestation. In suitable candidates with a strong desire for vaginal birth, amniotomy induction has been one option.