Vaginal Birth After Caesarean (VBAC)

Is VBAC Right for You?

If your current pregnancy and health history are considered low-risk, you are a good candidate for a successful vaginal birth after caesarean (VBAC). However, you may have one or more conditions that lower your chances of a successful trial of labour and increase your risk of complications. As you and your health professional decide whether VBAC is right for you, consider the following information.

You are a good candidate for a successful trial of labour and VBAC if you have had one caesarean birth using a low transverse incision AND:^{1, 2}

• Your baby is normal in size and in the head-down (vertex) position.
• Labour has started on its own (spontaneously) and your cervix is dilating well.
• No medical reason exists for a caesarean delivery with this pregnancy. (Possible medical reasons for having a caesarean include placenta previa, breech position, narrow pelvis, triplets or more, and active genital herpes.)
• You want to have a trial of labour and a vaginal delivery.
• You can deliver in a hospital that offers VBAC and has the ability to do a rapid emergency C-section.

Should I have a VBAC trial of labour after a previous caesarean?

As with a first-time childbirth, even if you are a good candidate for a successful VBAC, there is no guarantee that you will give birth vaginally and without complications.

You and your doctor may consider a VBAC if:¹²

• You have had two caesarean births using low transverse incisions AND a vaginal delivery. (The risk of uterine rupture increases with each additional scar. But a history of at least one vaginal birth greatly lowers this risk in women with two caesarean scars.)
• The type of incision used for your prior caesarean is unknown (previous surgery records are not available), but your health professional can judge that it is a low transverse scar based on why you had a caesarean section.
• You are carrying twins and they are positioned properly inside your uterus.
• You have delivered vaginally and by caesarean before and are now carrying a very large fetus with an estimated weight of 4 kg (9 lb) to 4.5 kg (10 lb). The larger the fetus, the less chance there is of delivering vaginally.
• Labour has not started on its own, but your cervix is soft and partially dilated. If you have a medical need to deliver right away, your doctor may carefully use oxytocin (Pitocin) to start labour. Your doctor may also place a thin tube with a small balloon into the cervix. This can soften the cervix without raising the chance of uterine rupture.

VBAC is not considered safe if you have:¹²

• No access to a hospital that can offer close monitoring and is equipped to handle an emergency caesarean delivery.

You are not a good candidate for VBAC if you have factors that increase the risk of uterine rupture, including:^{1, 2}

• Labour that has not started on its own and a cervix that is closed and firm. This is especially true if you have never had a vaginal delivery. In this case, starting labour with medicine, such as misoprostol (Cytotec), raises the risk of uterine rupture during VBAC. (If oxytocin is used carefully to help a slow labour, it is less likely to increase your uterine rupture risk.)^{1, 3} Some doctors place a thin tube with a small balloon into the cervix. This can soften the cervix without raising the chance of uterine rupture.
• A vertical (classical) uterine incision that reaches above the lower uterus.
• Two or more caesarean scars and no previous vaginal delivery.¹
• A caesarean section within the past 2 years.⁴
• A single-layer closure (rather than a double-layer closure) of your previous caesarean section.⁵
• Previous uterine surgery, such as removal of a uterine growth (fibroid) that has cut deeply into the uterus.
• A narrow (contracted) pelvis, as determined during your last delivery.
• A breech fetus, positioned with the feet or buttocks down in the uterus.
• Triplets or more during this pregnancy.
• A medical reason for a caesarean, such as active genital herpes or placenta previa, in this 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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