Birth Matters

VBAC isn’t as safe as we thought?

Too often lately, I've heard from or about women who had a successful VBAC a few years ago but now are being told that "it isn't as safe as we thought" or even that they can't have another one, but rather have to schedule another cesarean. Obviously, if these women are being pushed into repeat cesareans, the woman who hasn’t yet had a VBAC is going to be even more out of luck.  Usually, they are told something about how the rupture risk is actually higher than originally thought; the hospital can't do the emergency cesarean as quickly as it needs to be done now, etc. Here are a few things to consider when you are told “VBAC isn’t as safe as we thought it was”:

First, while there isn't a lot of formal study on it, what research there is shows that if you have 1 VBAC with no rupture, your chances of having a rupture with a subsequent VBAC are extremely low (and usually associated with induction and instrumental delivery). So, basically, you've already "proven" your scar/uterus (I hate the language but that's the way an obstetrician would view it) and have an extremely low if not negligible risk of uterine rupture during the subsequent pregnancy.  From that standpoint, a second VBAC is even safer than it was the first time, whereas the risks of another cesarean are exactly the same as they've always been, with risk increasing rapidly during each cesarean after the first.

Second, it is correct that the rate of uterine rupture is now reported higher than it used to be, the literature reflects this. The cause is what's up for “debate”- many people have noticed that the rupture rate has climbed right along with the induction rate, and there's a large and growing body of research that shows pitocin induction, prostaglandin use and especially cytotec (misoprostel) all increase rupture rates significantly. Frankly, I'm not sure why this is still debated, other than because admitting induction is a real danger to women and their babies would present a pretty dilemma to the obstetrical community- instead, they would like to say that the rupture rate has always been this high, we just didn't notice or the studies were bad or some such smoke screen.  The rupture rate was not this high when VBAC first became mainstream in the U.S. and VBACs were almost never induced. The rupture rate remains low in many European countries, which interestingly enough have much lower induction rates too.  Hard to not believe there’s a connection between the two. 

Aside about induction: The national induction rate is supposedly about 18% (I find it hard to believe that its that low but anyway...) and I'm sure that some people think that 18% just couldn't be high enough to explain a rise in rupture rates from ~0.3% to 0.8+%.   I was thinking about it and I'll bet you a box of fine chocolates that the induction rate in VBAC attempts is significantly higher, because of the way VBAC and pregnancy in general are managed.  Why do I believe this?

Who are most of the women that end up with primary cesareans to begin with?

-Women who didn't go into spontaneous labor at 40 weeks and had failed inductions for being “overdue”.

-Women who had malpositioned babies causing a lot of prodromal or warm-up labor.   This ends up being a failed induction even though it’s called augmentation.  The women were induced, not augmented because they weren't in active labor when the interventions started.  Of course, this is the classic “failure to progress” scenario.

-Women who had larger babies (especially women who's obstetricians thought they had larger babies) and were either induced early or had panicky obstetricians that intervened in ways antithetical to birthing a larger baby.  This is the classic “cephalopelvic disproportion” scenario.  If you are lucky, you can get both FTP and CPD at the same time (though this doesn’t logically make much sense).

-Women who had pregnancy "complications" (dubious, in many cases) like “gestational diabetes” or border-line pregnancy induced hypertension that triggered interventions like early induction.

-Women of size, who are often the victims of early induction for a vast number of spurious reasons.

-Women who have a slow and easy labor pattern that "requires" augmentation, because it doesn’t stay on the now discredited Friedman Curve.

How many of these "conditions" are likely to repeat in the next pregnancy or at least be suspected of repeating? These same women are going to hear things like "We don't want that baby getting too big/blood pressure getting too high/blood sugar out of control this time so we'll induce early to give you a better chance at a VBAC" or "you must not be able to go into labor on your own, this is the second time you've gone past 41 weeks" or "you just seem to have an inefficient uterus when it comes to going into active labor, we need to give you a little pitocin to help".  I can’t help but think of one definition of insanity – to repetitiously use the same ineffective solution in an attempt to fix a non-existent problem.

To make matters worse, the already out-of-control fears many obstetricians bring to late pregnancy in a woman who has had one or more previous cesarean will exponentially increase all this drive to intervene.  Induction is the obstetrical panacea to all real and imaginary pregnancy complications. Unfortunately, rather than falling into a deserved disrepute, it’s slowly but surely being replaced by the scheduled cesarean, even in women who’ve had a vaginal birth already, or haven’t had a baby yet. Since I strongly suspect VBACs have been induced/augmented at a much higher rate than the general obstetrical population in the U.S., I expect that the rupture rate has increased dramatically right along with the VBAC induction rate.

I will also mention the current and ongoing debate over how the uterus is sutured after a cesarean.  The type of uterine closure is used as yet more fodder in the “VBAC isn’t as safe as we thought” war.  It’s a somewhat complicated issue and I will address it in more detail elsewhere.   Suffice it to say that some women with a single-layer closure of their uterus are now being told that they have much higher risks associated with attempting a VBAC and should be encouraged to have a repeat cesarean instead.  As usual, the situation is much more nuanced than these blanket statements would indicate.  There is simply no compelling evidence that a single-layer uterine closure makes VBAC too risky.

The number that often gets thrown around with regard to the "decision to incision" time in an emergency cesarean is 17 minutes (a dramatic change from the previously and broadly acceptable 30 minutes). It’s based on a single, small study.  Other studies have confirmed that outcome is not so closely tied to a particular “decision to incision” time, and in some cases there was less morbidity and mortality with longer times!  Certainly one small study should not be strong enough to warrant such a drastic change in national obstetrical practice but it does have the advantage of making it easier for the obstetrical community to get what it really wants – the (false) perception of complete control over the process (which is why, in general, they won't give up induction unless its in favor of elective c/s). If its reasonable to require a 17 minute rule for VBACs then it ought to be reasonable to require it for all births -- because an abruption is just as catastrophic as a rupture (they are much the same thing) and occurs about as often (induction is also implicated in abruption rates). The same is true of umbilical cord prolapse, another potentially life threatening emergency which often (though not always) necessitates an immediate cesarean (the almost ubiquitous artificial rupture of membranes, considered a “benign” form of induction, is implicated in umbilical cord prolapse.  I see a pattern emerging. Insanity anyone?).

The fact of the matter is, if you have a catastrophic rupture (a small proportion of all uterine ruptures) then your baby might die no matter where you are and no matter how quickly you get to surgery. Being able to have surgery within 17 minutes might save your baby but it might not -- what it will do is make it harder for you to successfully bring suit against obstetrician and hospital because if the decision to incision time was within 17 minutes, s/he can say s/he did everything according to the latest research, according to ACOG’s most recent guidelines and there's nothing more that could be done.  Act of God.

The other effect of the 17 minute rule is to significantly reduce the pool of women "eligible" for a VBAC at all and this is viewed as a very good thing in the obstetrical community – as many have said, no one gets sued for the cesarean they did, just the cesarean they didn't do. The only thing that has changed about VBAC is how it’s managed and the medico-legal politics surrounding it. A non-medicated VBAC now is just as safe as it was 20 years ago -- the increased risk now is iatrogenic for mom and baby and legal for the obstetrician.  It is true that there have been some very high award lawsuits over uterine ruptures and neonatal death/morbidity.  Some of the very vocal early proponents of VBAC were involved (after, in my opinion, having become quite cavalier about VBAC management) and have done 180 degree turns on the issue.  It is not unusual to read recommendations for a 50% cesarean rate in this country!  Sadly, the cesarean rate in N. America looks to be approaching 50%, with dramatic increases every year.  I don’t see the pendulum swinging back until women and babies dying due to cesarean complications is recognized by the popular culture. 

When it comes down to it, if VBAC was safer than a repeat cesarean the first time you did it, it continues to be safer now, as long as you don't increase your risks by consenting to procedures or interventions that are known to increase risk.  If VBAC used to be safer than a repeat cesarean for most women, it still is, as long as you don’t irresponsibly increase risks. By informing you of the all the "recent findings about increased risk", your obstetrician is actually informing you of the increased risk s/he is taking by attending a VBAC, especially if an induction is in the plans.  Perhaps you will be given the “choice” of going into labor spontaneously by some ridiculous date (38 weeks seems to be popular) or an “elective” cesarean at 39 weeks.  Most likely, you will be “offered” an “elective cesarean at 38 weeks, to save your obstetrician the worry that you just might go into spontaneous labor after all.  After all, we can’t have our surgeons worried, now can we?   That would be insane.

revised June 16, 2006