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