Twin Deliveries - East Meets West : Maternal-Fetal Medicine

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Twin Deliveries - East Meets West

Barrett, Jon1,∗; Zhou, Qiongjie2,3

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doi: 10.1097/FM9.0000000000000108
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The West

The literature regarding mode of delivery was limited to observational studies and retrospective cohort studies until the publication of the Twin Birth Study (TBS) in 2013.1 In retrospective studies in UK, birth order and delivery interval have been investigated.2 Smith et al. reported that vaginally delivered second twins had a four-fold risk of death, which was caused by intrapartum anoxia,2 while Leung’s study showed that risks of fetal distress and acidosis in the second twin were high when the twin-to-twin delivery interval is beyond 30 minutes.3 Before TBS, only one small scale randomized controlled trial was performed, in 1987. In this study, Rabinovici and colleagues aimed to assess the management of a non vertex twin B.4 They randomized 60 women carrying twins (in all of which twin B was in breech presentation or transverse lie) to planned vaginal delivery (VD) vs. planned cesarean delivery (CD). All twins A were in cephalic presentation. They did not find any significant differences between the groups in Apgar scores, birth trauma, neonatal morbidity or mortality, but stated that maternal febrile morbidity was significantly higher in the CD group.

As aforementioned, all other studies were mainly observational or retrospective in nature. A systematic review and meta-analysis published in 2011 by Rossi et al. included such manuscripts published in the first decade of the millennium.5 Their main results showed that while as a general rule the rate of neonatal morbidity of twin A is lower than twin B, it is not associated with mode of delivery, or presentation of twin B. They also reported lower rate of neonatal morbidity of twin A in VD (as compared with CD).5

In an effort to reconcile different results from different studies, a multi-national, multi-center, randomized, controlled trial was initiated in 2003.1 In the TBS, patients were eligible for recruitment between 32+0/7 and 38+6/7 weeks of gestation, if the first twin was in the cephalic presentation, and both fetuses were alive with an estimated weight between 1500 g and 4000 g. Exclusion criteria were monoamniotic twins, fetal reduction at 13 or more weeks of gestation, lethal fetal anomaly, contraindication to labor, or VD (such as fetal compromise, twin B substantially larger than the twin A, previous two or more CD’s or vertical uterine incision, etc.). Women were randomized to planned VD or planned CD, and delivery was planned between 37+5/7 and 38+6/7 weeks of gestation. Mothers and infants were followed up to 28 days after delivery. The primary outcome was defined as one or more of the following: neonatal mortality, birth trauma, 5-minutes Apgar score <4, alteration in consciousness, two or more seizures before 72 hours of age, need for assisted ventilation with an endotracheal tube, septicemia or meningitis, necrotizing enterocolitis, bronchopulmonary dysplasia, grade III or IV intraventricular hemorrhage, cystic periventricular leukomalacia. Additionally, a composite maternal outcome was also defined (one or more of the following): maternal mortality, blood loss ≥1500 mL, need for blood transfusion or need for dilation and curettage after delivery, laparotomy, serious genital tract injury, intraoperative damage to the bladder, ureter, or bowel requiring repair, fistula involving the genital tract, thromboembolism, systemic infection or pneumonia, major medical life-threatening illness, serious wound infection or complication, or other serious maternal complication.

Overall, data were available for a total of 1392 women in each arm, 2783 fetuses/infants in the planned CD arm and 2782 fetuses/infants in the planned VD arm. Approximately 90% of women assigned to the planned CD arm had a CD, 9% had a VD of both twins, and 1% had a combined delivery. In the planned VD arm, 56% patients had a VD, 40% had a CD for both twins, and 4% had a combined delivery. Of this cohort, approximately 75% had dichorionic-diamniotic twins, and the rest had monochorionic-diamniotic twins.

No differences in the primary composite neonatal outcome or the composite maternal outcome were found between the groups. These results did not change in the pre-specified sub-group analysis according to parity, gestational age at randomization, maternal age, presentation of twin B, chorionicity, or the national perinatal mortality rate of the mother’s country of residence. It was found, however, that the second twin was more likely than the first twin to have the primary outcome.7 The authors of the study concluded that planned CD was not associated with better neonatal or maternal outcomes than planned VD.

While this study was the first (and until today the only) comprehensive, large scale randomized controlled trial regarding mode of delivery in twin pregnancies, it still leaves several questions unanswered. First, one of first questions obstetricians face when counseling patients with twin gestation regarding mode of delivery, is the weight difference between the twins. The common notion is that if twin B is substantially larger than twin A, there may be an increased risk for CD or, more even more concerning, entrapment of fetal head when twin B is delivered in breech presentation. One of the TBS exclusion criteria was “second twin substantially larger than the first twin,” and fetal weight estimation by ultrasound was not analyzed. As such, the TBS does not answer this question, which is still a matter of debate.

Second, one of the TBS inclusion criteria for institutions was that VD of twins will be attended by “a qualified obstetrician who was experienced at vaginal twin delivery, defined a priori as an obstetrician who judged himself or herself to be experienced at vaginal twin delivery and whose department head agreed with this judgment”. Naturally, this definition is quite vague. As an attestation, a review of the TBS supplementary material reveals that out of the 59 combined deliveries in the planned VD arm, about 35%-60% were indicated by fetal malpresentation, and 6%-10% by failed attempted version.

Third, the TBS was not designed to answer other pertinent questions regarding multiple deliveries, such as delivery at lower gestational age or lower weight than specified, twin deliveries after previous cesarean section, and - as the TBS implies - higher order multiples. Fourth, the rate of failed attempted VD approached 45%. Since the TBS was designed and powered to answer the question of mode of delivery, it was not powered to address the question of risk factors for failed VD in twin gestations.

Following the publication of the TBS, several subanalyses were performed. While not sufficiently powered, they still shed light on several important questions, using the only large-scale, prospective study performed in this area. For example, Mei-Dan et al. sought to explore the differences between planned VD and planned CD for women in the TBS cohort who presented in spontaneous labor. Of the 2804 women included in the original study, 823 in the planned VD group and 612 in the planned CD presented in spontaneous labor. No difference in the rate of primary outcome was found between planned VD and planned CD groups. Similarly, the rates of the individual components of the primary outcome and of maternal adverse outcome were similar between the two groups. The authors concluded that in women with twins who present in spontaneous labor, a policy of planned VD compared with CD is not associated with significant differences in neonatal or maternal outcomes.6 The same group also explored the practice of induction of labor in twin pregnancies. They analyzed the outcomes of 153 women who were induced by prostaglandins, and 215 women who were induced by amniotomy and/or oxytocin alone. No difference in CD rate was found between the groups. In contrast, CD rates were affected by nulliparity, late maternal age, non-cephalic presentation of twin B, and high country’s perinatal mortality rate. There were no differences between induction methods with respect to maternal/neonatal adverse outcomes.7 The authors concluded that the need for cervical ripening by prostaglandin had no effect on the incidence of CD or adverse outcome in women with twins who requiring labor induction.

Neonatal outcome at 2 years of age were also assessed in the TBS cohort. Overall, 4603 children from the initial cohort of 5565 infants (83%) were included in the study. The authors found no significant difference in the outcome of death or neurodevelopmental delay (odds ratio (OR): 1.04, 95% confidence interval (CI): 0.77–1.41), and concluded that a policy of planned CD had no added benefit to children at two years of age compared with a policy of planned VD in patients with characteristics similar to the TBS cohort.8

Hutton and colleagues explored whether maternal outcomes 2 years after delivery, such as urinary stress, fecal or flatus incontinence, were affected by planned mode of delivery in twins. Overall, 2305 women out of the original cohort completed questionnaires at 2 years (82.2% follow-up). The authors found that women in the planned CD group were less likely to experience urinary stress incontinence compared with their CD group counterparts (OR: 0.63, 95% CI: 0.47–0.83), with no reported difference in the quality of life. No differences were found in fecal or flatus incontinence, or in other maternal outcomes.9

To conclude, the TBS was an important milestone in twins research, by providing reassurance to obstetricians regarding the feasibility and safety of planned VD in twin gestations with matching characteristics to those used in the study.

Several years after the publication of the TBS, these results were further validated by the JUmeaux MODe d’Accouchement study, a national prospective population-based cohort study in 176 maternity units in France.10 The inclusion criteria were similar to those of the TBS (twin pregnancies, born at or after 32 weeks of gestation, with a cephalic first twin). More than 5900 women and their neonates were eligible for analysis, of whom roughly 25% had a CD. The authors found that the composite neonatal mortality and morbidity was increased in the planned CD arm (5.2% vs. 2.2%, OR: 2.38, 95% CI: 1.86–2.05), but this difference was relevant only to those twins delivered before 37 weeks of gestation.

The East

In the East, twin delivery is also challenging for obstetricians. Twin is more prevalent than ever before worldwide accounting to wide usage of artificial reproductive technology and great portion of pregnant women aged 35 years old or higher. The prevalence in China has increased to 3.69/100 deliveries,11 and this rising trend is similar to their western counterparts. Thus, it is of great importance for maternal health.

In the view of published literature from our colleagues in the West,7–9 there is a general consensus that VD seems not worse than CD for achieving better pregnancy outcome, but also healthier life of the offspring. However, in China, there still lacks such well designed prospective studies for the comparison between CD and VD, and moreover, related studies are requiring to answering the questions such as the delivery methods, and outcomes for the second twins. Our guideline for clinical treatment of twinning pregnancy in 2015,12 has recommended an individualized selection of delivery method based on chorionicity, fetal presentation, pregnancy history and complications, cervical ripe, and fetal safety.

Although VD is indicted for substantial portion of twin pregnancies, CD rate was as high as 85%–90% in our reported 12 hospitals in China.12 The barrier for a planned VD in China is mainly from not only for pregnant women but clinicians as well. Due to possible combined delivery and potential medical affairs, patients and doctors are more likely to reach agreement for CD. Another important barrier is insufficient medical staff, environment, equipment, and protocols for VD of twin pregnancy and emergent CS, in primary or secondary hospitals, especially in rural China. Despite of the above barriers, an important disadvantage of CD is uterine scar and risk of uterine rupture in the next pregnancy. The likelihood of a next pregnancy after a twin delivery has not been reported in China. Further study is indicated for the choice for a CD in twin pregnancy.

Therefore, to promote a safer VD of twin pregnancy in different maternal hospitals, we propose a training bundle aiming for cultural cultivation and standardization. First, it targets at education for our pregnant women and medical staff. Pregnant women and their families should be well recognized with the benefits and harms of different delivery methods and therefore participate in making decision with their obstetricians. Second, regular training for VD of twin gestation is recommended to further promote capability in clinical treatment. This model for qualifying our medical staff has been proved in our previous clinical training of ultrasound determination of chorionicity.13 Since ultrasound determination of chorionicity was poor in early pregnancy in China, a multi-centered cohort study was conducted to increase the accuracy rate of prompt chorionicity determination in 12 hospitals without fetal medicine centers. Among 2998 twin pregnancies extracted, the rate of overall chorionicity determination, including antenatal and postpartum diagnosis, substantially increased from 49.5% in 2014 to 93.5% in 2017, along with increased rate of ultrasonic chorionicity diagnosis before 14 weeks from 25.2% in 2014 to 65.0% in 2017. More interestingly, decreasing incidence of preterm birth, a lower risk of stillbirth, and a decreased rate of admission to neonatal intensive care unit were also observed. Thus, standard stimulation and training for obstetricians and teamwork is of great importance. The concerns in “the West” is the growing lack of experience in manual obstetric maneuvers, including forceps, version, and extraction. Similar situation is observed in China. Therefore, formal training on simulators during residency is of great importance, and this simulation is already included in our residence training program. In addition, regarding of some unanswered questions such as indication and contraindication for VD of twin pregnancy, high-quality clinical research is required in the future. If twin B is estimated 120% weight as twin A or 750 g greater than twin A,11 CD is preferred in China. Those pregnancies before 32 gestational weeks, estimated weight less than 1500 g and previous history of Cesarean section, who are excluded for VD considering greater risk of neonatal asphyxia, fetal brain hemorrhage, and uterine rupture.

Twin pregnancy is also an opportunity for Chinese obstetricians to learn clinical and research experience from our western colleagues to promote a safer and healthier VD.



Conflicts of Interest


Editor Note

Jon Barrett is an Associate Editor of Maternal-Fetal Medicine. The article was subject to the journal’s standard procedures, with peer review handled independently of this editor and their research groups.


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Edited By Yiyuan Jiang and Yang Pan

How to cite this article: Barrett J, Zhou Q. Twin Deliveries - East Meets West. Maternal Fetal Med 2022;4(4):251–254. doi: 10.1097/FM9.0000000000000108.


Twins; Delivery; Vaginal delivery; Cesarean section

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