There is only one substantial study of higher-order VBACs. Miller (1994) had 1,827 TOLs in women with 2 or more cesareans. Of these, there were 241 TOLs in women with 3 or more prior cesareans (VBA3+Cs). Overall, the rupture rate was found to be 1.7% in all VBAMCs combined; 1.8% in VBA2Cs, but only 1.2% in VBA3+Cs. This seems to contradict the theory that rupture risk rises linearly as the number of prior incisions rises. However, these labors may just have been managed with more caution (i.e., less induction and augmentation), thus decreasing the risk of rupture. Without more details, we cannot know. But the 1.2% rupture risk in the VBA3+C group is close to the 1% “acceptable” rupture risk commonly cited for VBA1C. Therefore, higher order VBACs should not be categorically denied either.
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