Is VBAC Safe?

You ask:

I really want a VBAC, but I am so scared of uterine rupture. Are VBACs a safe option?

I answer:

Unfortunately, there’s a lot of misinformation about the risks of VBAC floating around. Here, however, are some facts from one of my recent blog posts: “How Often Does the Scar Give Way in VBAC Labors?”

Two studies, both with nearly 60,000 participants, reported that the odds of having the scar open were 3 to 5 per 1000 VBAC labors.^{6, 9} That’s 995 to 997 out of 1000 odds of not having a problem with the scar. What’s more, planning VBAC rarely resulted in severe adverse outcome for the baby or mother, and severe adverse outcome rates were similar between planned VBAC and planned repeat cesarean:⁹

• hysterectomy
  • 6 per 10,000 with VBAC labor
  • 6 per 10,000 with planned repeat cesarean
• newborn death
  • 2 per 10,000 with VBAC labor
  • 1 per 10,000 with planned repeat cesarean
• newborn seizures
  • 14 per 10,000 with VBAC labor
  • 6 per 10,000 with planned repeat cesarean

Even with newborn seizures, a symptom of possible neurologic injury, the difference between planned VBAC and planned repeat cesarean was fewer than 1 per 1,000 with planned VBAC. Furthermore, some, and probably most babies, will experience no long-term ill effects,⁴ making an excess possibility of permanent injury extremely unlikely.

In addition, severe adverse outcomes in VBAC labors are almost always a consequence of the scar giving way, and studies show that the risk of the scar giving way can be moderated by labor management. The lowest scar rupture rates are seen when labor begins and progresses on its own. Rates increase markedly when labor is induced or when a labor that began spontaneously is strengthened with IV oxytocin and especially when labor induction includes treatment for an unfavorable cervix.^{1, 5, 8, 10} Studies also show that scar rupture rates rise in parallel with maximum oxytocin dose and duration at maximum oxytocin dose.^{2, 3} This means that the odds of the scar giving way can be minimized by waiting for labor to begin on its own, engaging in practices that promote labor progress such as walking,⁷ and having patience with slow progress. My blog post has more on this issue.

Finally, any risks of planned VBAC are only half the story. Also to be considered are the comparative risks of planned repeat cesarean and the risks of accumulating cesarean surgeries. My post “Should You Plan a VBAC or a Repeat Cesarean?” has more information on those.

I hope this sets your mind at ease. If you decide to go for a VBAC, my post on whether to plan a VBAC or a repeat cesarean includes tips on choosing a VBAC care provider.

References

1. Al-Zirqi I, Daltveit AK, Forsen L, et al. Risk factors for complete uterine rupture. Am J Obstet Gynecol 2017;216(2):165 e1- e8.
2. Cahill AG, Stamilio DM, Odibo AO, et al. Does a maximum dose of oxytocin affect risk for uterine rupture in candidates for vaginal birth after cesarean delivery? Am J Obstet Gynecol 2007.
3. Cahill AG, Waterman BM, Stamilio DM, et al. Higher maximum doses of oxytocin are associated with an unacceptably high risk for uterine rupture in patients attempting vaginal birth after cesarean delivery. Am J Obstet Gynecol 2008;199(1):32 e1-5.
4. de Vries LS, Cowan FM. Evolving understanding of hypoxic-ischemic encephalopathy in the term infant. Semin Pediatr Neurol 2009;16(4):216-25.
5. Goer H. The case against elective repeat cesarean. In: Goer H., Romano A., eds. Optimal Care in Childbirth: The Case for a Physiologic Approach. Seattle, WA: Classic Day Publishing; 2012.
6. Guise JM, Eden K, Emeis C, et al. Vaginal birth after cesarean: new insights. Evid Rep Technol Assess (Full Rep) 2010(191):1-397.
7. Lawrence A, Lewis L, Hofmeyr GJ, et al. Maternal positions and mobility during first stage labour. Cochrane Database Syst Rev 2013;10:CD003934.
8. Wallstrom T, Bjorklund J, Frykman J, et al. Induction of labor after one previous Cesarean section in women with an unfavorable cervix: A retrospective cohort study. PLoS One 2018;13(7):e0200024.
9. Young CB, Liu S, Muraca GM, et al. Mode of delivery after a previous cesarean birth, and associated maternal and neonatal morbidity. CMAJ 2018;190(18):E556-E64.
10. Zhang H, Liu H, Luo S, et al. Oxytocin use in trial of labor after cesarean and its relationship with risk of uterine rupture in women with one previous cesarean section: a meta-analysis of observational studies. BMC Pregnancy Childbirth 2021;21(1):11.

Medical Disclaimer: Henci Goer is neither a physician nor a midwife. Content and information on this website are for informational and educational purposes only and do not constitute medical advice. Users are advised to consult their physician or midwife when making decisions about care.