Twin delivery: does induction of labor make a difference?

Archives of Gynecology and Obstetrics https://doi.org/10.1007/s00404-025-07939-2 MATERNAL-FETAL MEDICINE Twin delivery: does induction of labor make a difference? L. Rüegg1,3 · L. Vonzun1,2,3 · J. Wawrla‑Zepf1,3 · F. Krähenmann1,2,3 · N. Ochsenbein‑Kölble1,2,3 Received: 23 May 2024 / Accepted: 7 January 2025 © The Author(s) 2025 Abstract Purpose Induction of labor as well as delivery in twin pregnancies bears specific risks. The goal of this study was to analyze the delivery mode in twin pregnancies and influence of induction on the cesarean delivery (CD) rate and perinatal outcome and to identify risk factors for CD and an intertwin interval ≥ 15 min. Methods This single-center retrospective cohort study analyzed the outcome of 267 twin pregnancies. Inclusion criteria for vaginal delivery in twins are gestational age (GA) > 34 weeks, leading twin in cephalic presentation, estimated weight difference ≤ 500 g and no previous uterine surgery. Women were divided into three groups: 1 = vaginal delivery, 2 = CD for both twins, 3 = emergency CD for second twin. Outcomes were mode of delivery, and influence of induction on the CD rate. Results We had 156 women (58%) in group 1, 97 (36%) in 2 and 14 (5%) in 3. Induction of labor was performed in 147 cases and led to a higher CD rate (23% vs. 47%, p < 0.001). Induction of labor and nulliparity were associated with a higher risk for CD for both twins. Risk factors for an intertwin interval of ≥ 15 min were maternal age and weight of the second twin. An intertwin interval of ≥ 15 min was associated with a lower umbilical artery pH in the second twin. Conclusion The rate of CD doubled if induction of labor was necessary. These results emphasize on careful patient counseling that includes information about the risks of deliveries in twin pregnancies. Keywords Twins · Twin delivery · Mode of delivery · Induction of labor · Intertwin interval What does this study add to the clinical work Induction in twin pregnancies can increase the rate of cesarean delivery. In this single center cohort study the delivery mode of twins was analyzed and the results can influence counselling women expecting twins to make an informed decision about their chosen delivery mode and about possible risks of induction of labor and risks for the second twin. * L. Rüegg 1 Department of Obstetrics, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland 2 The Zurich Center for Fetal Diagnosis and Therapy, University of Zurich, Zurich, Switzerland 3 University of Zurich, Rämistrasse 71, 8091 Zurich, Switzerland Introduction The prevalence of twin pregnancies has doubled in many countries since 1970 mainly due to the rising maternal age and increased use of reproductive medicine [1–3]. Twin pregnancies are at risk for various complications such as preeclampsia, growth restriction or intrauterine fetal demise [4–7]. They have a higher fetal and maternal morbidity and mortality rate [8], especially near term. Thus, several guidelines recommend elective delivery of uncomplicated dichorionic twins around 37–38 gestational weeks (GW) and at around 37 GW in monochorionic twins [9–14]. Whether induction of labor in twins leads to a higher cesarean delivery (CD) rate is still under debate [15–20]. During vaginal delivery, the second twin faces a higher risk than the first [21, 22]. After successful delivery of the first twin, insufficient contractions, malpresentation, placental disruption or prolapse of the umbilical cord can complicate the delivery of the second twin, and a manual extraction, vaginal operative measurements or even a delivery via CS for the second twin can become necessary [23]. The ideal time frame, in which the second twin should be delivered, is still under discussion. Vol.:(0123456789) Archives of Gynecology and Obstetrics Several studies demonstrated a longer intertwin interval to be associated with an increased morbidity of the second twin [24–26]. Therefore, it is often recommended to deliver the second twin within 15 min after the first [27]. The primary aims of this study were to evaluate delivery mode in twins at our center and analyze whether induction of labor increases the frequency of CD for both twins or of emergency CD for the second twin. The secondary aim was to identify risk factors for CD of both twins, emergency CD in the second twin or an intertwin interval of ≥ 15 min. Methods Patients and study design This is a retrospective single-center cohort study. Between 2004 and 2022, a total of 2628 twin deliveries took place at our tertiary center. Unfortunately, 1706 were ruled out due to missing informed consent. Of the remaining 922 pregnancies, 321 women had a scheduled primary CD. Indication for primary CD in twins at our centers includes leading twin not in cephalic position, leading twin > 500 g smaller than the second twin, previous CD in medical history or mothers wish due to the twin pregnancy. Further, we excluded preterm deliveries before 34 weeks (N = 116) because we only deliver twins vaginally after 34 weeks at our center. Also, women with delivery due to the beginning of labor before scheduled CD (N = 148) or with loss of pregnancy (N = 70) were excluded from this study. Criteria for a vaginal delivery in twins at our center were as follows: gestational age (GA) > 34 weeks, leading twin in cephalic presentation weighing at least 2000 g, estimated birth weight difference ≤ 500 g, no previous uterine surgery. Induction was performed due to maternal or fetal indications such as GA (until 2018 all twins were induced after completing 38 weeks since 2018 uncomplicated dichorionic–diamniotic twin pregnancies are induced between 37–38 GW and monochorionic–diamniotic pregnancies around 37 GW according to the recommendations for management of twin pregnancies of the German, Austrian and Swiss Society for obstetrics and gynecology [11], premature rupture of membranes (PROM) or preterm premature rupture of membranes (PPROM), oligohydramnios, intrauterine growth restriction (IUGR), mild preeclampsia, pregnancy hypertension, suspicious cardiotocography (CTG) pattern, cholestasis of pregnancy or also the wish of the mother. Induction in twin pregnancies was performed according to the induction protocol of our department with intravenous application of oxytocin for 6 h (5 IE in 500 ml) with a running rate starting at 12 ml/h. Dose was increased by 12 ml/h every 30 min until regular contractions (4/10 min) were present. After 6 h, a break of at least 4 h was mandatory before starting the next cycle. If unsuccessful, either the insertion of a uterine balloon (CookBalloon®) for 24 h (or until dislocation) or the application of vaginal misoprostol (misoprostol 25 µg, every 4–6 h, up to a maximum of 6 doses) was discussed and applied on patient’s agreement. When patients refused induction and decided for primary CD, they were excluded from this study cohort. Indication for CD was an individual decision in ea (...truncated)