Clinical factors associated with failed trials of labor in late preterm and term twin pregnancies.

Objective: To evaluate the perinatal outcomes and clinical factors of unsuccessful trials of labor (TOLs) in late preterm and term twin pregnancies.

Methods: We enrolled 896 consecutive twin pregnancies delivered between 1999 and 2012 in a single center, which met the following inclusion criteria: a vertex first twin, live twins, and attempted TOLs after 34 weeks. Obstetric characteristics and perinatal outcomes were compared between vaginal delivery and cesarean delivery groups.

Results: Successful TOLs were carried out in 81% (726/896). Failed TOLs occurred in 15% (37/247) of late preterm twins and 20% (133/649) of term twins. Comparisons of neonatal outcomes between the groups showed no significant differences in NICU admission, ventilator use, and composite morbidity. On univariable analysis, nulliparity, preeclampsia, induced labor, excessive weight gain, and intertwin weight discordance of >30% showed significant associations with failed TOLs. Multivariable analyses revealed nulliparity (adjusted odds ratio 9.89, 95% confidence interval 4.64-21.1) and preeclampsia (adjusted odds ratio 2.17, 95% confidence interval 1.30-3.63) as significantly associated with failed TOLs.

Conclusion: In late preterm and term twins, trials of labor can be performed successfully without a significant increase in adverse neonatal outcomes. Nulliparity and preeclampsia are clinical factors associated with failed TOLs in twin pregnancies.