Objective: To estimate the occurrence and to assess clinical predictors of emergent cesarean delivery in the second twin after vaginal delivery of the first twin.
Methods: We conducted a population-based cohort study, using the 1995-1997 linked mother/infant twin data from the United States. The adjusted risk ratios and population attributable risks of clinical predictors of emergent cesarean delivery in second twins were estimated for the overall study sample and for those born at less than 36 or 36 weeks or more of gestation.
Results: Among the 61,845 second twin births with the first twin delivered vaginally, 5,842 (9.45%) were delivered by cesarean. The cesarean delivery rate was increased in infants born to mothers with medical or labor and delivery complications. Breech and other malpresentations were the most important predictors of emergent cesarean delivery for the second twin (population attributable risk 33.2%; 95% confidence interval 31.8%, 34.6%). Operative vaginal delivery of the first twin was associated with a decreased risk of cesarean delivery for the second twin. Prediction of emergent cesarean for the second twin by clinical factors was stronger in term births than preterm births.
Conclusion: In the general population, the cesarean delivery rate for the second twin after vaginal delivery of the first twin is approximately 9.5%. With the presence of breech and other malpresentations, the need for emergent cesarean delivery of the second twin after vaginal delivery of the first twin is increased by 4-fold.
Level of evidence: II-2