Abstract
BackgroundMode of delivery remains a topic of debate in vertex/non-vertex twin pregnancies. We used the WHO Global Survey dataset to determine the risk of adverse maternal/perinatal outcomes associated with presentation of the second twin, following vaginal delivery of a vertex first twin.MethodsWe analysed a derived dataset of twin pregnancies ≥ 32 weeks gestation where the first twin was vertex and delivered vaginally. Maternal, delivery and neonatal characteristics and adverse outcomes were reported by presentation of the second twin. Logistic regression models (adjusted for maternal and perinatal confounders, mode of delivery and region) were developed to determine odds of adverse outcomes associated with presentation.Results1,424 twin pregnancies were included, 25.9% of these had a non-vertex second twin and Caesarean was more common in non-vertex presentations (6.2% vs 0.9%, p < 0.001). While the odds of Apgar < 7 at 5 minutes were higher in non-vertex presenting second twins (16.0% vs 11.4%, AOR 1.42 95% CI 1.01-2.00), the odds of maternal ICU admission (4.6% vs 1.7%, AOR 1.30, 95% CI 0.88-1.94), blood transfusion (6.0% vs 3.4%, AOR 1.23, 95% CI 0.67-2.25), stillbirth (7.6% vs 4.7%, AOR 1.15, 95% CI 0.72-1.73), early neonatal death (3.8% vs 2.1%, AOR 1.68, 95% CI 0.96-2.94), and NICU admission (26.6% vs 23.2%, AOR 0.93, 95% CI 0.62-1.39) were not.ConclusionAfter a vaginal delivery of a vertex first twin, non-vertex presentation of the second twin is associated with increased odds of Apgar <7 at 5 minutes, but not of other maternal/perinatal outcomes. Presentation of the second twin is not as important a consideration in planning twin vaginal birth as previously considered.
Highlights
Mode of delivery remains a topic of debate in vertex/non-vertex twin pregnancies
While evidence suggests that the second twin is at increased risk of perinatal morbidity at all gestational ages, [2] some experienced practitioners have expressed the opinion that the second twin presenting breech is at less risk than the second twin presenting vertex, as it may be delivered by breech extraction [3]
While the compared groups were similar in terms of maternal and perinatal characteristics, the higher rate of caesarean section in non-vertex presentations is suggestive of a preponderance for combined deliveries in this scenario, the rate of caesarean in the vertex-presenting second twins in our study (0.9%) is considerably lower than that reported by Yang et al (6.3%) [7] and Wen et al (9.5%) [17] in United States populationbased studies; we believe this reflects the lower rate of caesarean in the WHOGS participating countries [18]
Summary
Mode of delivery remains a topic of debate in vertex/non-vertex twin pregnancies. We used the WHO Global Survey dataset to determine the risk of adverse maternal/perinatal outcomes associated with presentation of the second twin, following vaginal delivery of a vertex first twin. A single randomised control trial (RCT) of 60 pairs of twins (second twin presenting non-vertex) compared caesarean to vaginal delivery. This trial demonstrated a significant increase in maternal febrile morbidity and a trend towards increased use of general anaesthetic in patients undergoing caesarean delivery. No perinatal deaths or significant neonatal morbidities were identified in either study group [9] This RCT was included in a Cochrane review that concluded there was inadequate evidence to recommend routine caesarean delivery in twin gestations with nonvertex presentation of the second twin – given the small sample size of the study with limited power [10].
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