Predicting Successful Vaginal Delivery Following C-Section

Vaginal birth after c-section | CU OB/GYNIf one or more of your prior pregnancies culminated in a cesarean delivery, you and your healthcare team will be faced with making a very important decision regarding the mode of delivery for this pregnancy. On the one hand, the best option may be to schedule a repeat C-section. On the other hand, you may be interested in attempting a vaginal delivery. This latter option commonly goes by two names. One is called a trial of labor following C-section (TOLAC). The other term commonly used for this choice is vaginal birth after C-section (VBAC).

A number of factors about will help inform your decision making process. Some of these factors have to do with your ongoing pregnancy. How is your health currently? Is your baby healthy? Is your baby breech?

Others have to do with your prior obstetric history, especially the pregnancy or pregnancies during which a C-section was performed. How many C-sections have you had? What was the indication for each prior C-section? What type of incision(s) was made on your uterus?

Estimating your chances for having a vaginal delivery

Assuming your care team thinks a vaginal delivery is a viable option, you may want to estimate your chances for being successful. Obviously, knowing the future is impossible. Reasons for recommending against a trial of labor include something called a placenta previa. This is the term used to describe a placenta that covers your cervix. As the cervix is the point of exit for your baby, the placenta really does need to be somewhere else to make a vaginal delivery safe.

The online MFM-U calculator

So the next best thing is the calculator sponsored by the Maternal-Fetal-Medicine Units Network. It appears on the website run by the National Institute of Child Health and Human Development (NICHD). This tool provides a research based estimate of your chance of having a vaginal delivery. I consult it on a regular basis. In case the links in this post are not working, the following web address can be copies and pasted into your browser:

What data to enter

To get your estimate, you will need to be able to answer 8 basic questions. These include your age, height, weight, and ethnic background. You then answer a series of questions about your prior deliveries. Some of these are more technical, so you may need help answering accurately. Once your data is entered, hit the calculate button, and there you have it.

I had a C-section for my twins, so it was possible for me to play with this calculator using my current health information. So just for fun, I determined that my chance of having a successful VBAC is between 64.8 percent and 73.9 percent. If I were 10 years younger, it would improve to around 77.2 percent. If I were 10 years older, well, the calculator does not go that high. But my doctors and I might make it into the National Enquirer.

Cool feature: Your calculation can be modified

One of the things I really like about this tool in clinical practice is that your estimate of success can be modified based on your physical examination at the time you are admitted in labor. The extra data that can be entered to modify your calculation includes your gestational age at the time, whether your labor is being induced, and how dilated or open your cervix is. Not surprisingly, your estimate can go up or down.

An estimate is just an estimate

As we mentioned earlier, nobody can predict the future. But this calculator can certainly help you and your health care team consider it. At the end of the day, everyone is eager for both you and your baby to have the healthiest outcomes possible. If this includes a vaginal delivery, so be it.


Part of the US Department of Heath and Human Service National Institutes of Health, the NICHD has as its mission to “The mission of the National Institute of Child Health and Human Development (NICHD) is to ensure that every person is born healthy and wanted, that women suffer no harmful effects from the reproductive process, and that all children have the chance to fulfill their potential to live healthy and productive lives, free from disease or disability.”

The VBAC Calculator is based on the following paper: Grobman WA et al, Does information available at admission for delivery improve prediction of vaginal birth after cesarean? American Journal of Perinatology, volume 26: 693-701(2009)

While this information was derived from reliable medical sources, it is not intended as a substitute for your personal medical care. Readers are directed to consult with their personal health care team members when addressing their individual healthcare needs.