Saturday, January 30, 2010

Is VBAC high-risk?

If I've heard it once, I've heard it a thousand times:

"My OB says VBAC is too risky and I should just have another c-section"
"Why would you risk your baby's life just so you can have a birth experience?"
"I'm having a repeat c-section because the most important thing is a healthy baby"

It wasn't that long ago that once you had a c-section, all your babies would be born that way. "Once a c-section, always a c-section" was the rule, and it was arguably a good one since cesareans were performed using a classic, up-and-down incision that extended well into the contracting portion of the uterus. That type of incision has a greater risk of rupturing during subsequent labors than the low-transverse incisions typically used today. With the risk of uterine rupture following a low-transverse c-section right around one-half of one percent, vaginal birth after cesarean (VBAC) has become a real option for women hoping to avoid future cesarean deliveries. And yet, controversy still surrounds the safety of VBAC vs. choosing repeat cesarean (RCS).

What is without question is that any pregnancy following a cesarean delivery carries significantly greater risk than a pregnancy in an unscarred uterus. Among those risks are higher incidence of placenta problems including previa, accreta, and abruption; higher risk of unexplained stillbirth; greater risk of preterm labor; and not least, uterine rupture. While we most often associate uterine rupture with a VBAC trial of labor, the reality is that even prior to labor, a woman with a previous cesearean delivery has a risk of rupture twelve times greater than a woman with an unscarred uterus having a normal vaginal delivery. The risk is still incredibly small- about 0.2% prelabor rupture for women choosing RCS, 0.4% rupture in a spontaneous VBAC, somewhat higher for induced or augmented VBACs- but without that scar, the risk is only 0.013%. Whenever we talk about delivery options for pregnancies after cesarean, I think it is important to recognize that we're not comparing VBAC (or RCS) to an uncomplicated vaginal delivery. We're comparing the available options, which are VBAC and RCS, and neither option is risk-free for moms or for babies.

Risk assessment is a personal thing and it's not surprising that when we are making decisions about something vitally important- how to get our babies out of our bodies and into the world- even the smallest risks can seem enormous. When we are pregnant the first time, it's just assumed we'll deliver vaginally. Once we have the option of delivering by VBAC or RCS, once we have to choose between risks, once we are forced to decide which set of horrific outcomes we prefer to chance- well, the decision isn't always an easy one. It's made even more complicated when women who want to choose VBAC are told that it's high-risk, or it's implied that they are selfishly pursuing an "experience" at the expense of their babies' health. OBs have endless "requirements" for VBAC moms due to the perception that it is risky- limits on gestation, limits on baby's size, "requiring" epidurals, requiring induction to ensure the hospital is fully staffed, requiring VBAC moms to deliver in the OR rather than an LDR room, continuous monitoring, internal monitoring, no laboring at home... you would think a VBAC mom's uterus is a bomb waiting to explode!! But is VBAC really high-risk?

The first thing I consider is how non-VBAC, vaginally birthing moms are treated. The potential for a complication requiring a truly emergency cesarean is there in any vaginal birth! Cord prolapse and abruption occur in .18% and .4% of labors respectively but those risks are not perceived as great enough to make all laboring mothers "high risk." In a VBAC labor, adding uterine rupture to prolapse and abruption, the risk of needing a truly emergent delivery is raised from about .6% to just under 1%. Does that increase justify a high risk designation?

And what about uterine rupture? Are the consequences of rupture so severe that even a small risk of rupture makes VBAC high-risk? While somewhere between 0.4% and 0.7% of VBAC labors will result in uterine rupture- a complete breach of the uterine wall- it's important to note that even a complete rupture is not always 'catastrophic' in the way that term implies. Less than 10% of complete ruptures result in permanent damage to mother or baby. 1 in 2,000 babies will suffer brain damage or death following u/r in a VBAC attempt. Is that "high risk?" If your answer is yes, would you change your mind if I told you that 1 in 2,500 mothers will die after choosing RCS?

Identifying a rupture when it occurs should be part of the equation, and the only sign that consistently occurs in the majority (but not all) of ruptures is a prolonged period of decelerations in fetal heartrate or bradycardia. This is also a sign of fetal distress in non-VBAC labors, and seems to be identified and responded to well in both hospital and non-hospital birth settings even without use of intervention like continuous monitoring or internal monitoring. Is that high risk?

What about outcomes? Recent studies are showing that women who choose VBAC have better outcomes overall than women who choose RCS. That's not comparing successful VBACs to RCSs either, it's comparing intended VBACs, whatever the outcome, with scheduled repeat c-section. Less NICU time, less respiratory morbidity, and less time in the hospital. Three times lower rates of infant death in the first month of life. Lower maternal morbidity and mortality. And that doesn't even begin to consider the impact of this birth on future pregnancies, an area where VBAC has clear advantages. High risk?

The additional risk of a cesarean scar follows a woman throughout her reproductive life and adds risk to all her future pregnancies. Uterine rupture is a real risk that is quite dramatically increased with a previous cesarean regardless of how a woman opts to deliver her future children. Women are absolutely entitled to do their own risk assessment and if they desire a more cautious approach to monitoring, both during pregnancy and during labor, they should be able to have that. However, given the increased risk of rupture even prior to labor's onset (which no one worries about), the better outcomes provided by VBAC, and the fact that providers should be ready for an emergent situation even in non-VBAC deliveries and those emergent situations occur with at least the same frequency as u/r, I don't think VBAC in and of itself should be labeled "high-risk."

(For further reading:


  1. Great post! I wish more of my friends and family understood my reasons for wanting a vbac. I hate that many of them think I'm taking an unneccessary risk, just to avoid being cut.

  2. You'll probably never know how much gratitude I have for you in my heart. Thank you for being a true advocate for mamas and babies, (and mamas scared to have a repeat of what happened with the first baby)

  3. Great post!

    It is so tough to figure out how to respond when a woman says she is choosing ERC because VBAC is "too risky." I know one woman who had a vaginal birth with her first child, then a vaginal birth with her second child (a twin), and a cesarean for her third child (the other twin). She chose a ERC for her 4th because "the risks of VBAC are just so high." I wanted to pound my head against the wall. I know she wasn't planning more children, so "future pregnancies" were not something she would consider...but she'd had 2 previous vaginal births! She was a GREAT candidate for VBAC, but I'd bet anything that her care provider scared her out of it. :-(

  4. It is unbelievable how many hospitals BAN VBAC! What do you do if you want the option to VBAC but the security of a hospital in case an emergency arises? I guess homebirth and 911 is the way around it. There is no medical reason for banning VBAC, it all boils down to insurance terminology.