To VBAC or not to VBAC?

Karen commented on my previous post about VBAC vs. ERCS:

…[I]n the majority of cases, a vbac will be safer for mom and baby, and the recovery is generally so much easier…

Overall, it’s true that most women – most studies I’ve found claim between 60-82% – of women given a trial of labor after one previous cesarean section will be able to successfully deliver their baby vaginally. That doesn’t mean, however, that “VBAC will be safer for Mom and baby”, as compared to the alternative, elective repeat CS. The reason for this is that CS’s are a relatively safe operation, especially if done under regional (epidural or spinal) analgesia and in a non-emergent fashion, and the 18-40% (on average) of women who are unsuccessful in their trial of labor and end up having a repeat emergency CS are subject to a high rate of morbidity, as are their babies. In fact, all things being equal, the odds slightly favor ERCS over VBAC. This has also been shown in practice in large studies. Most of the excess risk (as opposed to ERCS) is on the baby when a trial of labor fails, though there is also increased maternal morbidity in such cases. An comparison (.pdf file) based upon a few studies shows that ERCS is slightly more risky for the mother, whereas VBAC is slightly more risky for the baby:

Luckily for us (or unluckily, depending on who you are), not all things are created equal. The chance of VBAC success in any individual woman may be different from that of the cohort in general. In fact, in the past few years, different scoring systems based on risk factor profile have been suggested as a way to help predict the likelihood of any individual woman to undergo a successful VBAC. If such a scoring system is found reliable and universally accepted, this can be a wonderful guide for both pregnant women and their healthcare practitioners to making a decision to choose VBAC or ERCS based upon the woman’s specific situation. It should go without saying (though given human nature, it doesn’t) that in any case, the place to VBAC is where there is an appropriate obstetrics and anesthesia ‘safety net’ to deal with complications and perform a CS should it be necessary. It’s also a good idea to enable the staff to diagnose and treat complications that may arise ASAP – hence the recommendation for continuous EFM and venous access (heplock or IV).

Factors predictive of successful VBAC:

*Previous vaginal birth (either before or after the CS) – the more, the better

*One previous CS (the rates of uterine rupture are comparable with 2 CS’s, however major morbidity is greater than with 1 CS and as compared with a 3rd elective CS)

*Horizontal surgical incision on the lower segment of the uterus – it’s important to get the operative report of the CS, as a horizontal ‘bikini cut’ doesn’t necessarily mean the uterus was cut in the same manner.

* Delivery at least 19 months after the previous CS delivery

* Reason for the precious CS was a reason not likely to recur or that isn’t recurring in the current pregnancy (breech, fetal distress, placenta previa – as opposed to shoulder dystocia or cephalopelvic disproportion)

* Singleton birth in current pregnancy

*Labor begins naturally and does not require augmentation

*Mother is not obese

VBAC guidelines from the Royal College of Obstetricians, UK

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5 Responses

  1. I had my first VBAC five years ago after my first son was a CS for breech, so during that time they were largely seen as being equal in risk, if not just very slightly weighted to ERCS. Though, most OB’s in my town where the CS rate hovers around 40% were more likely to recommend an ERCS over anything else.

    At that time, I was quite interested in comparing the risk factors not for the 1st VBAC, but for the 3rd or more VBAC compared to a 3rd or more CS. At this time, I’m confident that my fourth pg is safer now that I’ve had two VBAC’s than it would have been had I opted for ERC’s for all my children. I can still have an ERC in a future pg, but I might not get there until I’m pretty sure I’ve had all the kids I’m going to have.

    FWIW, I’ve always done them in the hospital with the OB in the ward, heplock and all. Unfortunately, I did them unmedicated, which is sure to lose me some further brownie points…

  2. I agree. In 2000 (or 2003, as it were), VBACs were still being touted as an equally safe option. Of course, by the time I had my 2nd VBAC (in 2003), I was in a different risk category as someone who’d had a successful VBAC; I gave birth to my daughter at the same hospital where I had my CS, and nobody as much as batted an eyelash at my OB history.

    Oh, and medication, or lack thereof, does nothing to your brownie point score. 😉 . My daughter was also unmedicated, because I didn’t feel the need for it; However, I was annoyed (understatement of the year!) that people (and some books, like the awful Silent Knife) tried to actively scare me out of getting an epidural when I was researching my options towards my 1st VBAC. I probably would have opted for an ERCS if I didn’t know how to find better information.

  3. I had 1 vaginal delivery before my 2nd son was born – breech presentation requiring csection (after hours of labor…dilation…) for my 3rd, I chose a VBAC – the best recovery of all my deliveries – VERRY HAPPY with reults… and now with the 4th I am hoping to have another successful VBAC though with this one I am 39 weeks plus and nervous the baby will be too big?! all my other children were born in the 38th week and were 6lbs 10 oz to 7lbs 1 oz. So, we’ll see how this turns out – I’d be interested to know if the size of the baby has any bearing on the success rate of a VBAC?!

  4. Well, if the baby is huge and you’re a small woman, it might, but if you don’t have gestational diabetes and are not prone to birthing huge babies, and this is not your first VBAC, I can’t imagine this being of great concern. Presumably, your OB has had you do an US to estimate fetal weight – though this can be misleading at times. Always discuss these issues with your care provider regarding your specific situation, however.

  5. I, too, had 1 successful vaginal delivery before my 2nd and 3rd son and I am hoping to do a VBAC for my fourth child.

    My first child was born vaginally successfully after going into spontaneous labour at 35 weeks. However, as her lungs were underdeveloped, I lost her a mere 5 hours after she was born.
    2nd was born by C-section as I was experiencing issues – my hip joints were so swollen I could not walk and the pain was excruciating when I moved – Am a bit ashamed to say that I requested for that C-section.
    3rd – i tried to go VBAC and my dr was supportive but he suggested inducing labour as the baby looked large – he measure 3.9kg at 37 weeks. I agreed but after 6 hours of 45 second long contractions which were 1 minute apart – i did not progress beyond 3cm. The dr broke my water and i was still at 3 cm after another 5 hours… so I went under the knife…emergency c-sections are the worst..!!!
    This pregnancy has gone relatively smoothly… I was eating healthier and exercising before the pregnancy…and i think that helped much… i want to try vbac again for this one and i am weighing the pros and cons… i do not know of anyone who’s had a successful VBA2C. My dr would only consider VBAC if i arrive at the hospital 8cm dialated. I want to labour at home before going to the hospital but I am afraid if a complication arises before i get to the hospital. On the other hand, if i go to the hospital immediately the drs & nurses will insist on strapping me down and i think labour would not progress quickly if I am on my back…
    Am weighing the options but would like anyones feedback on this matter… my hubby wants an elective c-section as it is less hassle for everyone….

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