The Likelihood of Change in Fetal Presentation During the Third Trimester in Twin Pregnancies

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To estimate the likelihood and identify predictors of spontaneous fetal version during the third trimester in twins using data from a multicenter randomized controlled trial on mode of delivery in twin pregnancies.


Women with twin pregnancies after 32 weeks of gestation in which twin A was vertex were randomized to planned cesarean or planned vaginal delivery. In the current study we analyzed the likelihood of a spontaneous version of any of the twins between ultrasound assessment at the time of randomization and delivery.


A total of 2,603 women were analyzed. Twin A tended to persist in the vertex presentation after 32 weeks of gestation with a spontaneous version rate to nonvertex presentation of 3.0% (95% confidence interval [CI] 2.3–3.7%). Twin B was less stable and underwent spontaneous version in 24.8% (95% CI 23.1–26.5%) of cases; the rate remained higher than 20% even after 34 weeks of gestation. On multivariable analysis, twin A was more likely to undergo version when twin B was smaller (adjusted odds ratio [OR] 2.0, 95% CI 1.04–3.3), when twin B was breech (adjusted OR 3.7, 95% CI 2.2–6.4) or transverse (adjusted OR 2.9, 95% CI 1.6–5.5), and when the interval to delivery exceeded 4 weeks (adjusted OR 2.5, 95% CI 1.3–5.0). Twin B was more likely to undergo version when it was in the breech presentation (adjusted OR 1.7, 95% CI 1.4–2.1) or transverse lie (adjusted OR 3.1, 95% CI 2.5–3.9) compared with vertex presentation, when it was smaller (adjusted OR 1.7, 95% CI 1.1–2.0), when the interval to delivery exceeded 4 weeks (adjusted OR 1.7, 95% CI 1.3–2.4), and in multiparous women (adjusted OR 1.3, 95% CI 1.04–1.5).


The likelihood of spontaneous version of twin A after 32 weeks of gestation is low when twin A is in the vertex presentation but is much higher for twin B, even late during the third trimester.




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