McKesson Clinical Reference Systems: Women's Health Advisor 2002.2

What is a vaginal birth after cesarean delivery (VBAC)?

Women who have given birth to a child by cesarean delivery ought to be encouraged to give birth to the next child vaginally. More than half of the women who attempt vaginal birth after one previous cesarean delivery (VBAC) have successful vaginal births. VBACs are now being encouraged by doctors because, compared to a cesarean section, labor and vaginal delivery are generally safer for women and as safe for the baby.

You should understand that if you do not want a VBAC under any circumstances, you have the right to refuse to have one.

What is a trial of labor?

A trial of labor is when you are allowed to go into natural labor and start the process of vaginal delivery while being carefully monitored.

If your doctor says you can have a trial of labor, you should go to the hospital when your labor begins or when your bag of waters breaks. Your labor is monitored. Your health care providers will test your blood type and group. You will have an IV or saline lock so you can quickly be given IV fluids or medication if needed. You will be allowed to continue your labor and a vaginal birth if there is no evidence of problems for you or your baby.

Your contractions may be stimulated with small doses of oxytocin. If there are signs of abnormal bleeding, abnormal fetal heart rate patterns, or failure to make adequate progress in labor, you will have a repeat cesarean birth.

When can a VBAC be done?

Your doctor will consider certain facts about your last delivery or deliveries to decide whether you should have a trial of labor for vaginal birth. The main concern relates to the scar left in your uterus by the previous cesarean birth. You do not want it to come apart during labor or vaginal birth. Your doctor will encourage and allow you to have a trial of labor if:

• You had one or two low-segment transverse uterine incisions with previous cesarean deliveries. A low-segment transverse incision is a crosswise cut low in the uterus. (It is not the scar you can see in your skin.) The scar that results from this type of incision is stronger than the alternative vertical "classic uterine incision." Your doctor will look at your medical records to see which type of incision you had.
• You have already had a successful vaginal delivery after a previous cesarean delivery.
• Your pelvis is large enough for a vaginal birth.

VBAC is not recommended for all women. Your doctor will not allow a trial of labor if:

• An immediate emergency cesarean delivery can't be performed, if needed, because a surgeon, anesthesia, or sufficient staff are not available at the hospital.
• You have a classic uterine incision (a vertical cut in the uterus) from a previous cesarean delivery.
• You have a complication in your pregnancy that suggests that labor would not be safe for you or the baby.
• You are expecting more than one baby (for example, twins).
• Your baby is in the breech position (the baby's bottom or feet are down first instead of the head).
• You have a pelvis that is too small for a vaginal birth.

If it is expected that your baby will weigh over 8.8 pounds (4000 grams), this does not necessarily mean that you cannot have a trial of labor. But, your health care provider will need to watch your labor and delivery very closely.

What are the benefits?

These are the reasons it is good to try to have a VBAC:

• Less risk. Vaginal deliveries have fewer risks for you and the baby than cesarean delivery. Vaginal deliveries require fewer blood transfusions and result in fewer infections.
• Shorter recovery time. Your hospital stay is shorter and your recovery at home is faster with a lot less discomfort.
• More involvement. You and your family can be more involved with the birth. Excellent pain relief, such as an epidural, which numbs the lower half of the body, may be used during a vaginal birth.
• Usually less cost.

What are the risks associated with a VBAC?

The biggest risk for both you and the baby is that the scar from the previous cesarean delivery will tear and rupture the uterus during labor. However, the risk of uterine rupture is low. The risk is about 1.5% or less in women who have had one previous cesarean birth. If any signs of rupture do occur during labor, an emergency cesarean delivery will be done. An emergency cesarean delivery does carry more risk of infection and other problems than a scheduled cesarean delivery.

What should I discuss with the doctor?

If you have had a cesarean delivery, talk to your doctor about the possibility of a vaginal delivery for your next baby. Be sure to discuss the risks and whether or not you are a good candidate for a VBAC. Find out whether the hospital where you plan to deliver is prepared for an emergency cesarean delivery and emergency infant care if necessary.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.