Administration of corticosteroids to stimulate fetal lung maturation has not been well studied in multifetal gestation. However, these drugs logically should be as beneicial for multiples as they are for singletons (Roberts, 2006). In a large retrospective study evaluating betamethasone therapy eicacy in preterm twin versus preterm singleton pregnancies, no diferences in neonatal morbidity between the two groups were identiied (Melamed, 2016b). Gyamfi and associates (2010) evaluated betamethasone concentrations in women receiving weekly antenatal corticosteroids and found no diferences in levels between twins and singletons. Conversely, another study found lower cord/maternal ratios of dexamethasone in twin versus singleton pregnancies (Kim, 2017). hese treatments are discussed in Chapter 42 (p. 823). At this time, guidelines for the use of these agents do not difer from those for singleton gestations (American College of Obstetricians and Gynecologists, 2016).
The frequency of preterm premature rupture of membranes (PPROM) rises with increasing plurality. In a populationbased study of more than 290,000 live births, the proportion of preterm birth complicated by premature rupture was 13.2 percent in singletons (Pakrashi, 2013). This rate compared with rates of 17, 20, 20, and 100 percent in twins, triplets, quadruplets, and even higher-order multiples, respectively. Multifetal gestations with PPROM are managed expectantly similar to singleton pregnancies (Chap. 42, p. 820). Ehsanipoor and colleagues (2012) compared outcomes of 41 twin and 82 singleton pregnancies, both with ruptuted membranes between 24 and 32 weeks. They found the median number of days to subsequent delivery was overall shorter for twins-3.6 days compared with 6.2 days for singletons. This latency diference was significant in pregnancies after 30 weeks-l.7 days and 6.9 days. Importantly, latency beyond 7 days approximated 40 percent in both groups.
• Delayed Delivery of Second Twin
Infrequently, after preterm birth of the presenting fetus, it may be advantageous for undelivered fetus(es) to remain in utero. Trivedi and Gillett (1998) reviewed 45 case reports of asynchronous birth in multifetal gestations. Although reported outcomes may relect bias, pregnancies with a surviving retained twin or triplet continued for an average of 49 days. No advantage was gained by management with tocolytics, prophylactic antimicrobials, or cerclage. In their 10-year experience, Roman and associates (2010) reported a median latency of 16 days in 13 twin and ive triplet pregnancies with delivery of the irst fetus between 20 and 25 weeks' gestation. Survival of the irstborn neonate was 16 percent. Although 54 percent of the retained fetuses survived, only 37 percent of survivors did so without major morbidity. Livingston and coworkers (2004) described 14 pregnancies in which an active attempt was made to delay delivery of 19 fetuses after delivery of the irst neonate. Only one fetus survived without major sequelae, and one mother developed sepsis syndrome with shock. Arabin and van Eyck (2009) reported better outcomes in a few of the 93 twin and 34 triplet pregnancies that qualiied for delayed delivery in their center during a 17 -year period.