Vaginal Birth After Caesarean (VBAC)

What Affects VBAC Success

Pregnancy, labour, and delivery are different for every woman and difficult to predict. Even if your first pregnancy required a caesarean, the next one may not. The likelihood of a successful vaginal birth after caesarean (VBAC) is influenced by various factors. Usually, a combination of factors affects how well or poorly a trial of labour goes.

If you are or may be a good candidate for a trial of labour, your chances of delivering vaginally are best when:^{1, 2}

• Your previous caesarean was not done for stalled labour.
• You do not have the same condition that led to a previous caesarean (such as a breech, or feet-down, fetus).
• You have had a vaginal delivery or a successful VBAC before.
• Your labour starts on its own, and your cervixdilates well.
• You are younger than 35.⁶

If you are or may be a good candidate for a trial of labour, your chances of delivering vaginally are lower when:^{1, 2}

• Your previous caesarean was because of difficult labour, which is called dystocia. This is especially true if you were fully dilated when you had a caesarean section for dystocia.
• You are obese.
• You are older than 35.⁶
• Your fetus is very large [estimated as bigger than 4 kg (9 lb)].
• You are beyond 40 weeks of pregnancy.

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Author:	Kathe Gallagher, MSW Carrie Henley	Last Updated: June 18, 2007
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Kirtly Jones, MD - Obstetrics and Gynecology
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