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Uterine rupture risk drops significantly after first VBAC

As we know, the risks of cesareans increase with each surgery which is why family size should be considered when evaluating your post-cesarean birth options. Couple that fact with the results of Mercer (2008) which found that successful VBAC also provides a level of protection to future deliveries.

Mercer found that not only do the risks of uterine rupture, uterine dehiscence and other peripartum complications decrease after the first VBAC, but “VBAC success increased with increasing number of prior VBACs” to rates over 90% for women with two or more prior VBACs.  They also found that while two or more VBACs did not decrease the risk of rupture further (so a scarred mom’s risk of rupture never goes down to the risk of an unscarred mom), it’s important to note that the risk of rupture did not increase with subsequent VBACs as women are sometimes told in an effort to obtain their consent for a repeat cesarean.

Read the abstract below, link to the study abstract, or read the full text.

This is one of many studies that the journal Obstetrics & Gynecology provides to the public, full-text, for free without registration.

Mercer, B. M., Gilbert, S., Landon, M. B., & Spong, C. Y. (2008). Labor Outcomes With Increasing Number of Prior Vaginal Births After Cesarean Delivery. Obstetrics & Gynecology , 11, 285-91. Retrieved from http://journals.lww.com/greenjournal/Fulltext/2008/02000/Labor_Outcomes_With_Increasing_Number_of_Prior.6.aspx


OBJECTIVE: To estimate the success rates and risks of an attemptedvaginal birth after cesarean delivery (VBAC) according to thenumber of prior successful VBACs.

METHODS: From a prospective multicenter registry collectedat 19 clinical centers from 1999 to 2002, we selected womenwith one or more prior low transverse cesarean deliveries whoattempted a VBAC in the current pregnancy. Outcomes were comparedaccording to the number of prior VBAC attempts subsequent tothe last cesarean delivery.

RESULTS: Among 13,532 women meeting eligibility criteria, VBACsuccess increased with increasing number of prior VBACs: 63.3%,87.6%, 90.9%, 90.6%, and 91.6% for those with 0, 1, 2, 3, and4 or more prior VBACs, respectively (P uterine rupture decreased after the first successful VBAC anddid not increase thereafter: 0.87%, 0.45%, 0.38%, 0.54%, 0.52%(P=.03). The risk of uterine dehiscence and other peripartumcomplications also declined statistically after the first successfulVBAC. No increase in neonatal morbidities was seen with increasingVBAC number thereafter.

CONCLUSION: Women with prior successful VBAC attempts are atlow risk for maternal and neonatal complications during subsequentVBAC attempts. An increasing number of prior VBACs is associatedwith a greater probability of VBAC success, as well as a lowerrisk of uterine rupture and perinatal complications in the currentpregnancy.


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8 thoughts on “Uterine rupture risk drops significantly after first VBAC

  1. maha

    It would be nice if the site shows doctor names who allow VBAC. My and alot of my friends are looking for ones in CA, but still no results.

    This would be a great profit idea for the VBAC doctors.

  2. Pingback: Бързи факти – VBAC vs. ресекцио « Zozima’s Blog

  3. Joanna

    After having an emergency CS for a breech baby with my second, I have had three VBACs in the last 4 years. It’s been difficult to find docs that will allow me a VBAC but the group I’m with now is really anxious to not put me under the knife. With all three VBACs I’ve been given Pitocin and my last was an official induction as I was not in active labor by my due date.

  4. Pingback: facts on vbacs « Elan Doula

  5. Angela Healy

    I would be interested if these successful VBAC’s were induced or not. I had a successful VBAC after being induced at 41 weeks, got pregnant 12 months later, was induced at 41 weeks again, and had a complete uterine rupture up my left side. The doctors only gave me petocin for 3 hrs then discontinued it as my contractions had become too intense too early. For the following 14 hours my labor progressed nicely on it’s own. I ruptured when I was about 7 cm.

    1. Jen Kamel Post author


      I am so sorry about your uterine rupture!

      The Mercer 2008 study does provide rupture rates for spontaneous and induced labors in the body of the study.

      Here is what they found.

      Of the 9,012 women who did not have a prior successful VBAC: 0.87% spontaneous labors ruptured vs. 1.37% induced labors.

      Of the 2,900 women with one prior successful VBAC: 0.45% spontaneous labors ruptured vs. 0.37% induced labors.

      Of the 1,620 women with two or more successful VBACs: 0.43% spontaneous labors ruptured vs. 0.63% induced labors.

      Note that populations of less than 5,000 women do not measure the rate of uterine rupture as accurately as populations greater than 5,000, but this is the best study to date regarding rupture rates after successful VBACs.



  6. Tara

    I have been searching for this information.

    It is fantastic to find a study that isn’t just about the first VBAC.

    Thanks for posting it.

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