UCHealth Ask An Expert:: VBAC

We are so thankful to our UCHealth OB/GYN partner, Charles Lalonde, MD, for taking time to answer our important questions submitted by our community of moms regarding VBAC.
Ask an Expert

Once upon a time, expectant mothers were told that if they delivered a baby by Cesarean section, all their remaining children would have to be delivered the same way. The myth persists, so some would-be moms worry about that.

Here’s the real skinny on the subject of vaginal birth after C-section (VBAC), using questions sent in by our readers answered by UCHealth OB/GYN Charles Lalonde, MD. (Note: Some questions have been grouped because of their similarity.)

Q: “What advice do you offer women who are considering VBAC?”

Q: “What criteria does a woman have to meet to be considered for VBAC?”

A: Normally, the success rate of a VBAC is around 70% and there are some important factors that will increase the chance of a successful VBAC.  

As an example, let’s go with the presumption that you were pregnant three years ago and you had your baby by C-section. The reason for the C-section has a large implication as to what the success rate will be later on if you attempt to deliver your next baby vaginally. If the previous baby was a breech delivery, this next time around, the baby is head first (we call that vertex), that wouldn’t be a recurring indication. Contrast that with someone else who got to eight centimeters and after 4-5 hours with us pushing Pitocin and trying to get her to 10 centimeters to push, she never progressed beyond that. There is more of a chance of that happening the next time around but we still think a VBAC is worth attempting. 

One of the things that we want to see is spontaneous labor — that increases the chance of your success. We want you to have a very favorable cervix, meaning it’s dilated, thinned out and soft when you go into labor. You also have a slight increased chance of a successful VBAC if your BMI (body mass index) is under 30 and if you’re younger than 35. 

There’s three real strategies when it comes to VBACs. There’s the old school “once a C-section, always a C-section.” The second strategy is to do a TOLAC – trial of labor after Cesarean in hopes of a successful VBAC. The third option is that we would schedule a C-section around your due date in the hopes that you would go into spontaneous labor, which would increase the chance of a successful VBAC.

Q: “What are the risks of a VBAC?”

Q: “I know both VBACs and repeat C-sections pose risks and advantages. I am worried that I may try the “safest” option (a successful VBAC) and end up in a risky situation (emergency c section) if things don’t progress as planned. What have you seen in your experience?”

Q: “I’ve heard things regarding risks of having a VBAC after a C-section…can you put the risk of uterine rupture into perspective? What do you tell or recommend to your patients assuming they have no medical complications or previous risks?”

A: The primary risk of a VBAC is that the contractions of the uterus can cause the uterus to open or rupture. This risk is uncommon (about one in 100), but can be serious for both the mother and baby (10-25 percent chance of death or brain damage to the baby if the uterus ruptures). Risks to the mother of the uterus ruptures include the need for emergency surgery which may involve removal of the uterus (hysterectomy) and significant risks of blood loss or infection.  

If you have a successful VBAC, that’s best for mom and baby and quicker for mom’s recovery. However, about 30 percent of the time, we do have to do a C-section and within that 30 percent, about one out of 100 of those is an emergency C-section because the heart tracing went south in a hurry. Although an emergency C-section may be needed with a VBAC attempt, it’s generally uncommon.  

Q: “Is there anything a woman can do during pregnancy to help her achieve a successful VBAC?”

A: Having a BMI under 30 increases the chance for a successful VBAC. Also, spacing children out after the first C-section can help. Besides that, the other factors needed to achieve a successful VBAC will happen when the woman is in labor. 

Q: “Why would a woman consider a VBAC?”

A: For the VBACs that are successful, the mom will recover more quickly after delivery. Something to consider is that it takes longer to recover with each subsequent C-section. The more C-sections you have, the higher the risk of the placenta adhering in and around the lower uterine segment where the incision is made. Especially when it’s placenta percreta, there’s an increased risk of developing placenta accreta, and that’s where you cannot remove the placenta and you have to do a Cesarean hysterectomy and that can lead to tremendous amounts of blood loss.

Q: “I have heard and read that VBACs are more successful the younger you are. I am 34, in great shape and hope to have another child in the next few years. What guidelines do you recommend regarding age when it comes to attempting a VBAC?  Is there a certain age that you will not recommend a VBAC?”

A: I would attempt a VBAC at almost any age but I tell people that when you are 35 and older, there’s a slight decrease in success rates. While normally the success rate for a VBAC is around 70 percent, it might be around 60-65 percent for a woman older than 35. 

Q: “My first baby had low amniotic fluid and was breech so I had a C-section for safety reasons. Can you talk me through the criteria that you would consider to be a candidate for VBAC? Would you even recommend I try a VBAC with a second baby given my first delivery situation?”

A: This hopefully will not be a recurring indication (which would decrease the success rate for a VBAC) since with low amniotic fluid, it didn’t give the baby the opportunity to do a half flip and come in head first. This time around, if the baby is head first, I would say go for it. 

Q: “I’ve had two C-sections so far. I would love to attempt a VBAC with my third. Would this be a possibility you would recommend?”

A: If all the stars line up, then yes. For a woman in a similar situation, I would schedule a C-section for about a half a week before her due date, and I would say if she comes to the hospital in labor and her cervix is very dilated, the heart tracing is exceptional, and labor is progressing well – these are all good signs for a successful VBAC. 

All VBACs attempting a trial of labor have to be monitored closely. For someone who has either not had a baby or if all her children have been vaginally delivered, we monitor the heart tracing for the first 30 minutes and if everything looks good, she can get up and walk and we do intermittent monitoring. But for women attempting a VBAC, we have to do continuous fetal heart rate monitoring so if there are signs of fetal bradycardia (an abnormally low fetal heart rate), we can catch it right away. 

Q: “My first baby weighed over 8 pounds when delivered via C-section. I would love to try a VBAC with my second pregnancy, but are there guidelines regarding large babies and not being able to safely attempt a VBAC if they get over a certain weight via ultrasound?”

A: We would want to screen for gestational diabetes around 26-28 weeks and assuming the test is negative, want to review your obstetrics to answer the following questions:  How far did you get?  How far did you dilate?  Did you push for hours and the head was too high? 

Q: “Is it possible to be induced with a VBAC delivery or does labor have to start spontaneously regardless?”

A: Yes, but I prefer spontaneous labor. And if we’re going to induce, the cervix has to be very favorable and that has to do with the Bishop score.

The factors that make up the Bishop score are that the more dilated you are, the lower the head is in the pelvis, the softer the cervix, the more in line with the vaginal canal, the higher the likelihood of a successful vaginal delivery. We just call it a “favorable cervix.” The higher the score, the higher the success rate of a vaginal delivery. 

Q: “If a woman is pregnant with twins her second pregnancy, is a VBAC even an option? If so, does she have to be monitored throughout her pregnancy more frequently than a normal VBAC?”

A: The risks of rupture are greater for subsequent pregnancies if the combined weights of the babies and amniotic fluid is much larger than the first. If you went into spontaneous labor, both babies were head first, and both heart tracings are good, I would consider (but not necessarily encourage) doing a VBAC. 

Q: “How does labor and delivery during VBAC differ from labor and delivery during a routine vaginal birth?”

A: The key difference is that we have to do continuous fetal heart rate monitoring because one of the first signs of rupture (which is a 1 in 100 risk) is a prolonged fetal heart-rate deceleration. 

Q: “Do you have to wait a certain amount of time after a C-section to get pregnant and try for a VBAC?”

A: There isn’t a specific time recommendation, but I would say six months minimum and others may say a year. You want things to heal — if you deliver via C-section and three months later, you are back to being pregnant, I wouldn’t encourage a VBAC. 

But again, if all the stars aligned, and a C-section is scheduled but the expecting mom comes on to the labor floor and is six centimeters dilated and the heart tracing looks good, then we may consider a VBAC.  However, we don’t see people having back-to-back pregnancies as much we used to. 

Q: “At what point during labor is the decision made to do a Cesarean if a VBAC isn’t progressing according to plan?”

A: Let’s say we have a woman who on her first pregnancy, made it up to eight centimeters but stayed there for hours even with Pitocin and ended up having a C-section, we wouldn’t let that happen again the second time around. Our decision to proceed with a C-section will be a little bit quicker if we have a recurring theme between pregnancies. 

Q: “I had an “anchor” style C-section (vertical and horizontal incisions due to complications) with our first child. Does that automatically rule out VBAC with future pregnancies?”

A: Unfortunately, this rules out a VBAC for future pregnancies because the risks for rupture are much higher and they can be catastrophic. The thick muscle layer in the top two thirds of the uterus has a large blood supply and can be catastrophic if that ruptures. For vertical incisions (which are called a classical C-section), sometimes we have to do classical C-sections because of significant degrees of prematurity. If a mom delivers at 24-27 weeks, sometimes the lower uterine segment hasn’t developed and you cannot make a side-to-side or horizontal incision and a vertical incision is needed. For someone who had a classical C-section, they are not a candidate for a VBAC. 

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About Charles Lalonde, MD

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Charles Lalonde, MD is an OB/GYN at UCHealth Printers Park OB/GYN. Dr. Lalonde is board certified in Obsetrics and Gynecology and he went to medical school at the University of Ottawa and completed his residency at the University of Manitoba in Winnipeg. Dr. Lalonde is fellowship trained and has over 21 years experience as an OB/GYN in Colorado Springs. He was listed in the Consumer’s Research Council of America’s “Guide to America’s Top Obstetricians and Gynecologists.” Dr. Lalonde also specializes in minimally invasive gynecologic surgery and teaches these techniques to local OB/GYNs in the Colorado Springs community. Outside of his practice, Dr. Lalonde has completed the Seven Summits; climbing the tallest mountain on all seven continents. He also runs with the local Incline Club and has completed the 13-mile Pikes Peak Ascent every year since 1999.