By Ahizechukwu C. Eke, MD, PhD, MPH

Assistant Professor in Maternal Fetal Medicine, Division of Maternal Fetal Medicine, Department of Gynecology & Obstetrics, Johns Hopkins University School of Medicine, Baltimore

Dr. Eke has no relevant financial relationships with ineligible companies to disclose.

SYNOPSIS: In this randomized clinical trial by Tong and colleagues, 343 pregnant women with twin gestations were randomized to planned cesarean delivery and planned vaginal delivery groups (208 patients vs. 135 patients, respectively) between October 2013 and March 2015. There were no statistically significant differences in the composite primary neonatal outcome (which occurred in 1.9% of neonates in the planned cesarean delivery arm vs. 2.2% in the planned vaginal delivery arm) and secondary outcomes in women randomized to planned cesarean delivery compared to those randomized to planned vaginal delivery. The cesarean delivery rate in the planned vaginal delivery arm was 49% compared to the cesarean rate of 99% in the planned cesarean delivery arm. If all criteria for vaginal delivery are met, it would be reasonable and appropriate to offer women with diamniotic twin gestations planned vaginal delivery between 34 0/7 to 37 6/7 weeks of gestation.

SOURCE: Tong Y, Sun Q, Shao X, Han F. A randomized trial in comparison between planned cesarean and vaginal delivery on twin pregnancy. Ginekol Pol 2020;91:600-606.

The incidence of twin pregnancies has doubled in the last three decades, primarily as a result of increasing access to assisted reproductive technologies.¹ This rise in twin pregnancy rates has been associated with significant uncertainties about the optimal timing and mode of delivering twins, especially as training in breech extractions and assisted vaginal deliveries among obstetrics and gynecology trainees has declined, while cesarean deliveries for twin pregnancies have increased in the last decade.^2-4

The mode of delivery in twin pregnancies usually is determined by several factors, including the presentation of the leading twin, the estimated fetal weight of both fetuses, gestational age, estimated weight differences (weight discordance) between both fetuses, concomitant maternal medical conditions that contraindicate vaginal delivery, and maternal preference.⁵ When the leading twin is cephalic presenting, and the estimated fetal weight discordance between both fetuses is < 20% (with the first being the larger twin), vaginal delivery and planned cesarean delivery both are options. In a 2013 publication, Barrett et al demonstrated that planned cesarean delivery did not reduce neonatal morbidity or mortality, with no short-term neonatal or maternal benefits when compared to planned vaginal delivery for delivery of twins between 32 and 39 weeks of gestation.²

In this randomized controlled trial, Tong et al reported their findings in women offered a trial of vaginal delivery compared to planned cesarean delivery for dichorionic twins.⁶ Women were included in this study if they met the following criteria: gestational age of between 32 and 39 weeks, leading twin in cephalic presentation, live fetuses, and estimated fetal weight of between 1,500 g and 4,000 g by ultrasound within one week of delivery. Women were excluded if they had monoamniotic twin gestation, presence of fetal anomaly not compatible with life, any contraindications to labor or vaginal delivery, prior participation in the Twin Birth Study, and a history of fetal reduction of one of the twins at > 13 weeks of gestation of the index pregnancy.

Using a centrally controlled computer randomization system, the participants were randomized to planned vaginal delivery or planned cesarean delivery. All fetuses were monitored continuously until the time of delivery. The primary outcome was a composite of neonatal morbidity and mortality and neonatal life-threatening conditions. Life-threatening conditions in the neonates included birth trauma within 72 hours after birth or at the time of discharge; subdural, intraventricular, or intracerebral hemorrhage; Apgar score < 4 at five minutes; coma; seizures on at least two occasions within 72 hours of birth; need for prolonged assisted ventilation using an endotracheal tube within 72 hours of birth; sepsis within 72 hours of delivery; necrotizing enterocolitis; pneumatosis intestinalis; bronchopulmonary dysplasia; or cystic periventricular leukomalacia. The secondary outcome was a composite of maternal death or serious maternal morbidity before 28 days postpartum, defined as one or more of the following: postpartum hemorrhage ≥ 1,500 mL; need for blood transfusion; need for dilatation and curettage after delivery; laparotomy; genital tract injury; third- or fourth-degree perineal lacerations; thromboembolism requiring anticoagulation; wound infection requiring prolonged hospitalization or readmission; wound dehiscence; or maternal death.

From October 2013 to March 2015, a total of 343 pregnant women met inclusion criteria. Two hundred eight women were randomized to the planned cesarean delivery group, and 135 women were randomized to the planned vaginal delivery group in a 2:1 ratio. The baseline characteristics were similar between both groups. The composite primary outcome occurred in 1.9% of the neonates in the planned cesarean delivery arm and in 2.2% of the neonates in the planned vaginal delivery arm but was not statistically significant. There were no statistically significant differences in the composite secondary outcomes in women randomized to planned cesarean delivery compared to those randomized to planned vaginal delivery. The cesarean delivery rate in the planned vaginal delivery arm was 49% compared to the cesarean rate of 99% in the planned cesarean delivery arm.

COMMENTARY

Based on available evidence from the Twin Birth Study, a landmark multicenter, randomized controlled trial published in the New England Journal of Medicine in 2013 by Barrett et al, there are no short- and medium-term neonatal or maternal benefits for planned cesarean delivery when compared to planned vaginal delivery.² In fact, a two-year neurodevelopmental follow-up study of 4,603 children from the initial cohort of the Twin Birth Study showed that a policy of planned cesarean delivery between 32 to 39 weeks of gestation did not offer any benefit when compared to planned vaginal delivery.⁷ In addition, a survey of the women who participated in both arms (planned vaginal and planned cesarean) in the Twin Birth Study demonstrated a preference for vaginal delivery, even in women who delivered by cesarean.⁸ Although the study by Tong et al demonstrated similar findings to the Twin Birth Study in the immediate postpartum period, follow-up studies of women and children in the randomized trial by Tong et al would be critical to demonstrate if medium- to long-term outcomes differ in women (and their children) randomized to planned cesarean compared to planned vaginal delivery.⁶

It is important to compare and contrast this study by Tong et al with the multicenter, randomized controlled trial by Barrett et al. Both randomized clinical trials are similar in several ways: Both recruited women with diamniotic twin pregnancies between 32 to 39 completed weeks of gestation, both had a central coordinating center (to reduce selection bias), and both had very similar primary and secondary outcomes. In addition, the cesarean delivery rate in the planned vaginal delivery arm in both trials (44% in the Twin Birth Study vs. 49% in the trial by Tong et al) and the cesarean delivery rate in the planned cesarean arm (91% in the Twin Birth Study vs. 99% in the trial by Tong et al) were very similar. However, the two clinical trials differ significantly in a number of ways. First, the sample size for the Tong et al trial was 343 women, while the sample size for the Twin Birth Study was 2,804 women (eight times the sample size of the Tong et al trial). Second, although both studies were multicenter trials, Barrett et al involved 106 participating centers in 25 countries while the trial by Tong et al did not report participating countries and centers. Third, in the Twin Birth Study, most women delivered between 32 and 37 weeks of gestation (83% of the women in both arms), while < 50% of women delivered between 32 and 37 weeks of gestation in the trial by Tong et al. Although both studies reported similar outcomes in the immediate postpartum period, the findings from the Twin Birth Study are more robust (based on greater sample size) and generalizable (a multi-country, multicenter randomized trial).

Based on these data, since planned cesarean delivery did not reduce the risk of fetal complications or serious neonatal morbidity at birth in both randomized clinical trials, it would be reasonable, and may be preferable and appropriate, to deliver women with diamniotic twin gestations between 32 and 39 weeks of gestation vaginally if the first twin is cephalic presenting and the estimated fetal weight discordance between both fetuses is < 20%. This is assuming there are no other contraindications to labor, and an obstetrician experienced in twin vaginal breech delivery is available.

REFERENCES

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7. Asztalos EV, Hannah ME, Hutton EK, et al. Twin Birth Study: 2-year neurodevelopmental follow-up of the randomized trial of planned cesarean or planned vaginal delivery for twin pregnancy. Am J Obstet Gynecol 2016;214:371.e1-371.e19.
8. Murray-Davis B, McVittie J, Barrett JF, et al. Exploring women's preferences for the mode of delivery in twin gestations: Results of the Twin Birth Study. Birth 2016;43:285-292.