Objective
The objective of the study was to establish predictors of vaginal twin birth and evaluate perinatal morbidity according to mode of delivery.
Study Design
One thousand twenty-eight twin pregnancies were prospectively recruited. For this prespecified secondary analysis, obstetric characteristics and a composite of adverse perinatal outcome were compared according to the success or failure of a trial of labor and further compared with those undergoing elective cesarean delivery. Perinatal outcomes were adjusted for chorionicity and gestational age using a linear model for continuous data and logistic regression for binary data.
Results
Nine hundred seventy-one twin pregnancies met the criteria for inclusion. A trial of labor was considered for 441 (45%) and was successful in 338 of 441 (77%). The cesarean delivery rate for the second twin was 4% (14 of 351). Multiparity and spontaneous conception predicted vaginal birth. No statistically significant differences in perinatal morbidity were observed.
Conclusion
A high prospect of successful and safe vaginal delivery can be achieved with trial of twin labor.
With advanced reproductive technologies, twin pregnancy rates have steadily increased over the past decade, such that they currently account for approximately 3% of all deliveries in the United States. This trend is inevitably accompanied by an increased perinatal morbidity and mortality burden. Although much of the disproportionate morbidity observed in multiple gestations (eg, congenital anomalies, preterm delivery) is not amenable to preventive therapy, careful selection of the optimal mode of delivery may represent one facet of twin pregnancy management in which decision making may potentially offer risk reduction.
However, the optimal mode of delivery for twins remains a contentious issue. Neonatal outcomes following vaginal birth of twins vs cesarean delivery have been the subject of several retrospective series and metaanalyses as well as one small randomized trial.
The aforementioned studies did not provide evidence to support cesarean in favor of vaginal delivery, yet large population-based studies have demonstrated an increased risk for neonatal morbidity and mortality of the second twin undergoing vaginal delivery. In light of these conflicting data gleaned from retrospective series, the optimal mode of delivery for twins is currently the subject of an ongoing randomized trial.
The objective of this study was to prospectively determine the factors that favor a successful trial of labor in twin pregnancies to include evaluation of neonatal morbidity according to mode of twin delivery.
Materials and Methods
A consecutive cohort of 1028 unselected twin pregnancies was enrolled for the ESPRiT study (Evaluation of Sonographic Predictors of Restricted growth in Twins), a multicenter prospective study conducted at 8 academic perinatal centers in Ireland, all with tertiary neonatal intensive care facilities, from March 2007 to June 2009. Institutional review board approval was obtained at each participating site, and the study participants gave written informed consent. For this prespecified secondary analysis, inclusion criteria were all twin pregnancies presenting to the study centers between 11 and 22 completed weeks’ gestation, with both fetuses alive at the time of prelabor cesarean delivery or onset of labor. Monoamnionicity, a major structural abnormality in either twin or fetal aneuploidy (either suspected or confirmed) led to exclusion from the study.
All prenatal and ultrasound data were contemporaneously transferred to an ultrasound software system (Viewpoint; MDI Viewpoint, Jacksonville, FL) and uploaded onto a live web-based central consolidated database. Pediatric outcomes for all twins not requiring neonatal intensive care were recorded by the research sonographer and uploaded onto the consolidated database. Infants requiring neonatal intensive care admission had their outcomes recorded by neonatology medical or nursing staff.
Management decisions relating to timing and mode of delivery were at the discretion of the lead clinician managing each twin case. Across all 8 centers, the intrapartum management protocol for twin birth included the routine use of regional anesthesia, continuous intrapartum fetal heart rate monitoring, and immediate access to the operating suite for emergency cesarean delivery, and all obstetricians in this system were trained in operative vaginal delivery, breech extraction, and internal podalic version. Tertiary-level neonatal care facilities were available in all 8 sites.
Maternal and obstetric characteristics were compared according to planned mode of delivery (elective cesarean section, emergency prelabor cesarean, or trial of labor) and further analyzed according to the success or failure of a trial of labor. Cesarean section was considered elective if cesarean delivery was chosen in the absence of any evidence of maternal or fetal compromise. This group included planned cesarean deliveries that ultimately were performed in early labor. Indications for emergency prelabor cesarean delivery were antepartum hemorrhage, nonreassuring fetal testing, and preeclampsia. Intrapartum cesarean delivery applied only in instances in which patients embarked on a trial of labor that did not succeed.
Neonatal intensive care unit or special care baby unit admission was recorded as indicators of neonatal morbidity. In addition, a composite measure of adverse perinatal outcome was analyzed according to mode of delivery. This measure included either perinatal mortality or any of the following: hypoxic ischemic encephalopathy (HIE), periventricular leukomalacia (PVL), necrotizing enterocolitis (NEC), respiratory distress, or sepsis.
A diagnosis of hypoxic ischemic encephalopathy was recorded in the setting of all of the following criteria: profound umbilical arterial academia (pH <7), persistence of an Apgar score of 3 or less for longer than 5 minutes, neonatal neurologic sequelae, and multiple organ involvement. Periventricular leukomalacia was diagnosed by neonatal ultrasound and subsequent magnetic resonance imaging.
A diagnosis of respiratory distress was considered for any infant requiring invasive or noninvasive respiratory support and was supported by radiographic criteria in which available and length of oxygen-dependence was recorded. A diagnosis of neonatal sepsis was determined with the support of positive microbiological cultures.
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