Wednesday, March 10, 2010

The decline of VBAC: hearing hoofbeats, thinking zebras

My daughter, who turns two years old in June, is becoming something of a medical rarity. This isn't because she is showing signs of a late-developing handicap or extraordinary ability for her age - it's because she came into the world as a vaginal birth after Cesarean section (VBAC), delivered by a certified nurse midwife. Although more than three-quarters of women who choose a trial of labor over a repeat Cesarean section successfully deliver vaginally, studies showing slightly elevated risks of rupture or infection of the uterus with VBAC, pressure from insurance companies concerned about lawsuits, and restrictive medical guidelines discourage most women from even trying. After reaching a high in 1996 of 28.3 percent of women who previously delivered by Cesarean, the national VBAC rate today is fewer than 1 in 10. As a result of all of these repeat Cesareans, 1 in 3 births in the U.S. today occur by Cesarean.

For the past two days, a conference at the National Institues of Health has sought to understand the reasons for the decline of VBAC, and what might be done to reverse what most believe to be a negative trend. Later this morning, an independent panel will release a draft statement summarizing the take-home points from the conference. What the statement probably won't say, but what I believe to be a large part of the truth, is that the U.S. has such a low VBAC and high Cesarean rate because Ob/Gyns deliver most of our babies, and Ob/Gyns aren't primary care clinicians.

The old medical maxim "when you hear hoofbeats, think horses, not zebras" refers to the fact that common conditions are more likely to present than rare or estoteric conditions. A dry cough, for example, is more likely to be due to allergies than Erdheim-Chester disease. Vomiting and diarrhea are much more likely to be caused by rotavirus than Vibrio vulnificus. Primary care clinicians internalize this maxim during their community-based training programs; specialist physicians - who spend most of their training learning to diagnose and treat "zebras" at academic medical centers where patients with uncommon conditions are referred for care - typically abandon it early on. And even though many women visit Ob/Gyns for routine gynecologic care, when it comes to the primary care-specialist attitude divide, Ob/Gyns come down clearly on the side of the specialists.

I could offer lots of anecdotes about why the above is true from having worked with Ob/Gyn physicians throughout medical school and residency training (when I delivered more than 80 babies and assisted in about half as many Cesarean sections), but objective data support the notion that labor managed by family physicians and professional midwives is considerably more likely to result in a vaginal birth than labor managed by an Ob/Gyn, even controlling for factors such as maternal age and risk status. It isn't difficult to understand why. If an Ob/Gyn is feeling uncertain about how well a patient's labor is progressing and has an inflated estimate of the probability that something might go wrong (the zebra), it's very hard to resist the temptation to eliminate the uncertainty by delivering the baby surgically, then and there. On the other hand, if the surgeon is at least a phone call away (the American Academy of Family Physicians' 2005 guideline on trial of labor after Cesarean noted that there's no good evidence that having a 24-hour on-call surgeon and anesthetist in-house improves maternal or infant outcomes), the family physician or nurse midwife might be more patient with the hoofbeats, betting they're hearing a horse. And, in fact, in a 2004 study of nearly 18,000 women who attempted VBAC, the most feared complication of uterine rupture (which requires an emergency Cesarean), occurred in less than 1 percent of cases. As mentioned earlier, a trial of VBAC is successful more than 75 percent of the time. It's a real shame that women in the U.S. are discouraged from attempting them more often.


  1. Great post, Ken! This may be the most egregious example of how we medicalize all aspects of normal life. Oh, and let's not forget the menopause!

  2. For my first birth I had an OBGYN who was all about the zebras and made me get induced (by telling me that I would be responsible for the death of my baby if I didn't get induced... even though my baby and I were healthy with no signs of complications at 41 weeks) before my body was ready, and thus ended in a successful, but unplanned c-section at 42 weeks.

    Thank you for putting into words what I have known, specifically about my obgyn. I am trying to find a new dr in the DC area that will do a VBAC for my second (not yet conceived) pregnancy... but, like you noted, it seems like all the obgyns see the zebras and insist on inducing (even if my body isn't ready) just because I hit some arbitrary date on a calendar.

    Do you have any reccomendations about who I should contact that would give me the best chance of a vbac?

  3. Dear Anonymous - I don't know anything other than what you've written about your medical history (nor is this blog a forum for providing specific medical advice), but provided that there aren't any unusual circumstances associated with your general health or first pregnancy, I would highly recommend this nurse midwife-led practice, which does VBAC at Washington Hospital Center:

    Good luck!

  4. Thank you for this wonderful post. Your support of primary care providers for pregnancy and birth care is right on, and you state it well.

    I also appreciate your use of the term 'professional midwife'. We midwives need to get better about using this term, rather then specifying one type or another. Professional midwives, of all types, have fantastic outcomes.

    Carrie Dickson, MS, CNM

  5. The article on the front page of the NY Times last Sunday about the availability of VBACs in federal health care facilities on Indian reservations made some important points about how our American health care "system" (industry is more accurate) predisposes most women to having primary and repeat cesareans. In the Indian reservation hospitals, midwives care for the basically healthy low risk women and call in the OBs when they are needed to handle complications and women with medical conditions putting them at risk. Doctors and midwives are salaried, and receive the same salary whether they perform vaginal or surgical births, thus taking away the ecoonomic incentive. Doctors live close by so they are able to get to the hospital quickly to handle a complication. If doctors and midwives work shifts their time spent at work does not depend on whether they attend a 24 hour labor or schedule a 1 hour cesarean. These are the very conditions that exist in other countries that have far better outcomes and spend far less money on maternity care. We need these reforms to the American health care system to make a difference...but without universal health care or at least a public option, it will probably be more of the same in the US in the years to come.

    Justine Clegg, MS, LM, CPM

  6. Instead of a universal health care system, how about just "Free Trade" in the health care arena. The problem as I see it is the restriction of trade placed on professional midwives by state statute and regulations that mean many women are denied access to midwifery care. This is the only part of the economy where certified, licensed professionals are placed in a dependent position on another profession. If a plumber or electrician wants to work with a general contractor or architect he/she can or he/she can choose to work independently. The lack of free trade in the health care field is one of the reasons that costs continue to rise. FREE THE MIDWIVES, and the country will reap the benefits.

  7. Great post. My "VBAC baby" is now 27; born when these were just "becoming OK" (before they became common and then rare).
    I am not posting it to my blog, but I am sending a link to it to the folks I notify about my blog posts. And putting it on my facebook page.

  8. Thank you for this post. My VBAC baby was born at home in 1996. I had CPM's attending with a FP doc for back-up. Ob's are trained surgeons...
    like the saying "if the only tool you have is a hammer, then everything looks looks like a nail".....If the only tool you have is a scalpel.....

    It boils down to less litigation and more money....less time away from the office and they don't have to "labor sit"....and more revenue for the hospital.

  9. Good post!

    I've had two recent hospital VBACs and encourage everyone I know with a prior c/s to VBAC if they're a good candidate. :)

  10. They SAY you can be cared for by your primary, but my primary KICKED ME OUT when he found out I was prego. I was low-risk and healthy 28 yrs old. They wouldn't see me and told me to find an OB/GYN and not come back until I had the baby. I was so stunned, I began bawling when I hung up with them...I felt rejected and panicked. I had read that low-risk pregnancies could be looked after that way, and they had done all my yearly exams for 5 years. I had no OB/GYN.

    In the end, it was for the best...I was forced to read up on my options and delivered naturally with a midwife at a birth center. Never thought it would pan out like that, but now I am so glad it did.