Mode of delivery outcomes of induced versus spontaneous labor in individuals with dichorionic twins.

Objective: To investigate odds of vaginal delivery comparing induced versus spontaneous labor in nulliparas and multiparas with dichorionic twins.

Study Design: Retrospective review of dichorionic twin pregnancies from 2008-2021. Those with scheduled or elective cesarean, malpresentation, prior uterine surgery, fetal anomaly, gestational age (GA) at delivery < 34 weeks, and multifetal reduction were excluded. Nulliparas and multiparas were analyzed separately. The primary outcome was vaginal delivery of both twins. Secondary outcomes included preterm delivery, postpartum hemorrhage, and hypertensive disorders of pregnancy (HDP). Outcomes were compared among induced versus spontaneous labor and assessed using univariable and multivariable logistic regression.

Results: Among 258 nulliparas, 176 (68.2%) were induced and 82 (31.8%) spontaneously labored. Induced patients were older (p=0.048), had higher proportion of intrahepatic cholestasis of pregnancy (IHCP) (p=0.04), HDP (p<0.0001) and later GA at delivery (p<0.0001). Patients who spontaneously labored had higher proportion of preterm delivery <37 (p<0.0001) and higher proportion of at least one twin admitted to the neonatal intensive care unit (p=0.01). On univariable analysis, induction was associated with decreased likelihood of vaginal delivery of both twins (p=0.01). However, after adjusting for augmentation, GA at delivery, gestational diabetes, and HDP/chronic hypertension, this was no longer statistically significant (p=0.14). Among 239 multiparas, 108 (45.2%) were induced and 131 (54.8%) spontaneously labored. Induced patients had higher proportion IHCP (p=0.02), chronic hypertension (p=0.02), HDP (p<0.0001), and later GA at delivery (p<0.0001). Spontaneous labor patients had higher proportion of preterm delivery <37 (p<0.0001). There was no significant difference in odds of vaginal delivery between spontaneous versus induced labor on univariate (p=0.74) or adjusted analysis after controlling for augmentation, GA at delivery, gestational diabetes and HDP/chronic hypertension (p=0.40) among multiparas.

Conclusion: Among nulliparas and multiparas with dichorionic twins, induction of labor does not appear to be associated with decreased odds of vaginal delivery.