VBAC: What ACOG Really Says {Birth Without Fear}

VBAC – Vaginal Birth After Cesarean.

The term and action is wrought with political and emotional meaning in the birth world. Can  you have a VBAC? Does your doctor or hospital “allow” a VBAC? Under what conditions can you have a VBAC? Should it be called a TOLAC (trial of labor after cesarean)? What sort of prior birth history is preferred? Once I have one successful VBAC, will I still have to jump through hoops in subsequent pregnancies?

All these questions and more come up when we start to discuss the mine field that is VBAC in today’s world. But I wanted to know what ACOG really says. I am not talking about the public statements – which you can read HERE. I want to know what ACOG is saying to the doctors, what they put out in their practice guidelines.

The document I found is HERE. I encourage you to not only look at the document for yourself, but to also follow the many links I have scattered throughout this article.

At the opening of the document, ACOG has this to say:

Trial of labor after previous cesarean delivery (TOLAC)* provides women who desire a vaginal delivery with the possibility of achieving that goal––a vaginal birth after cesarean delivery (VBAC). In addition to fulfilling a patient’s preference for vaginal delivery, at an individual level VBAC is associated with decreased maternal morbidity and a decreased risk of complications in future pregnancies. At a population level, VBAC also is associated with a decrease in the overall cesarean delivery rate (1, 2). Although TOLAC is appropriate for many women with a history of a cesarean delivery, several factors increase the likelihood of a failed trial of labor, which compared with VBAC, is associated with increased maternal and perinatal morbidity (3–5). Assessment of individual risks and the likelihood of VBAC is, therefore, important in determining who are appropriate candidates for TOLAC. The purpose of this document is to review the risks and benefits of TOLAC in various clinical situations and provide practical guidelines for managing and counseling patients who will give birth after a previous cesarean delivery.

Lets start with noticing that ACOG automatically terms all VBACs as TOLACs first. If you complete the trial with a vaginal birth, then it is a VBAC. The issue with this sort of wording (and thought process) is that it sets women up with doubt and it sets the doctor on the defense against the failure of the trial. I will use the term interchangeably only because the document that I am citing uses the term so often. But moving past this unfortunate wording we do see that they know VBACs are beneficial. They state that VBACs lower the maternal morbidity rate and risk of complications in future pregnancies and that as a whole they lower the cesarean rate. They do also point out that there are certain factors that make a TOLAC less likely to succeed, and that when they do “fail” you are more likely to have morbidity (which makes sense, as a major surgery is considered a morbidity to begin with).

In the “Background” section at the start of the Practice Bulletin we see several points that seem to be denied in the general obstetric community. First they state that the cesarean rate has increased rapidly since the 1970s, from 5% to more than 31% in 2007. They blame this increase on the introduction of electronic fetal monitoring, and the decrease in breech births and forceps births. I put emphasis on the EFM use, since we are often told that it is needed for a safe birth, even though research proves that it does not lower fetal morbidity or mortality. Again and again, research also shows that it increases the chances of a cesarean, which in turn increases the risks to mother and baby. Yet, ACOG still insists on the use of EFM as standard care.

They also state in this section that after the 1970’s VBACs gained popularity. By the mid 1990’s the rates of VBAC (28.3%) were such that it was actually reversing the cesarean rates. However, this increase in VBACs seemed to come with an increase in uterine rupture – though the literature does not state what sort of uterine scars were common (since certain types are known to have more risk, such as classical), whether induction was used, or what type of rupture occurred (most ruptures are not catastrophic but are instead considered a “dehiscence”). Due to this increase in ruptures, the case for VBACs was again set back to “once a cesarean, always a cesarean” in many practices. They finish this section by stating that it is known that liability is a large part of why VBAC is not offered to many women who are actually good candidates.

Now we get into the nitty-gritty of what they say about VBAC. I am going to take questions and statements from the document to break this down. All noted pages are from the Practice Bulletin unless otherwise stated or linked.

• What are the risks and benefits associated with TOLAC? (p2)
  • Neither an Elective Repeat Cesarean (ERC) or a TOLAC are without risks.
  • Most maternal morbidity that occurs during TOLAC is related to a failed attempt when a cesarean becomes necessary.
  • VBAC is associated with fewer complications than an ERC.
  • Thus, the risk of a VBAC really comes down to whether it is achieved. If it is a “failed” TOLAC it has more risk than an ERC, but if it succeeds, it has lower risk than a ERC.
  • The main risk of TOLAC/VBAC is a uterine rupture. However, as stated in the background, some studies do not give background information about what type of ruptures are occurring nor on what type of prior incision or induction methods.
  • They include a chart of maternal risk in this section and it is interesting to note that maternal death risk can be almost double (0.2%-0.4%) with a ERC compared to a TOLAC after one prior cesarean (0.2%), and that TOLAC with more than one prior cesarean had no death risk within those studies. It is also noted that a ERC also comes with the risk of uterine rupture (0.4%-0.5%).
  • It is noted that for families wanting several children a successful VBAC takes away the risks of multiple surgeries which includes hysterectomy, bowel or bladder injury, transfusion, infection, and abnormal placentation such as previa and accreta.
  • They include a chart of neonatal risk factors when comparing ERC to TOLAC. It should be noted that there is no significant increase in neonatal death or neonatal admission (NICU admission). We see a much higher rate of respiratory distress (1%-5% vs. 0.1%-1.8%), transient tachypnea (too much fluid in the lungs which causes breathing issues) (6.2% vs. 3.5%) and hyperbillirubinemia (jaundice) (5.8% vs. 2.2%) in babies who go through an ERC.
• What is the vaginal delivery rate of women who have a TOLAC? (p3)
  • Most studies show a 60-80% success rate.
  • Studies show a decrease in success if the same circumstances happen again, such as stalled labor, which lead to the first cesarean  (however, I will note that the definition of “stalled labor” is more likely the issue than anything else).
  • The chances of success are increased if the mother has spontaneous labor with no augmentation.
  • One VERY interesting note is that being “non-white ethnicity” lowers your chances of success. This speaks to the huge disparity in maternity care in ethnic groups in this country. Simply taking one look at the maternal mortality rate in non-whites gives a clear and horrible picture of this undercurrent in our maternity care system.
• Who is a candidate for VBAC? (p4)
  • The best candidate is one in whom the risks and benefits balance out in a way acceptable to the client and care provider, this may be different for each woman and there is no specific “formula” to come to this answer.
  • Decisions about the first VBAC should be considered with future pregnancies in mind. This is due to each subsequent cesarean increasing the risk for future pregnancies, and the inability in some areas to find care providers to attend a VBAC after multiple cesareans.
  • For most women with one prior cesarean and a low transverse incision VBAC is a good option and they should be counseled and offered a TOLAC. Women with other incisions (T-incision or classical) or with prior ruptures and surgeries of other sorts to the uterus should be evaluated more.
  • Individual factors should be considered in all cases (i.e. – no hard and fast decisions to ruling mothers out of VBAC), and in the case of women presenting in labor, VBAC should be strongly considered as spontaneous labor increases the success rate of a TOLAC.
  • More than One Prior Cesarean:
    • Studies addressing TOLAC in women with more than one prior cesarean find rupture rates ranging from o.9% to 3.7% – again, without specifying the type of prior incision or level of rupture. They also have not consistently compared these findings directly to women with only one prior cesarean.
    • One large study in particular found no significant increase in rupture between VBAC and VBAMC (vaginal birth after multiple cesarean) – o.7% vs. 0.9%. A second large study only found a slight increase – 0.9% vs. 1.8%. They also found no significant increase in morbidity.
    • The chances of success are similar to that of a VBAC after only one cesarean.
  • Macrosomia (Big Baby):
    • Some studies show a decreased chance of success with a baby larger than 4,000g, and posibily higher rupture rates. However, these studies are based on actual birth weights, and not the estimates given before birth. This is significant given the inability to accurately predict birth weight before the birth.
    • Suspected macrosomia alone should not rule out TOLAC.
  • Gestation of more than 40 weeks, according to the largest study done which looked at this factor, does not increase risk. There is evidence that after 40 weeks chances of success decrease but we must consider that induction of some sort may be common at that point (given current practice trends) and that lowers the chance of VBAC in general. Gestation of more than 40 weeks should not rule out TOLAC.
  • Previous Low Vertical Incision:
    • Studies show similar rates of success compared to low transverse incisions (the most common).
    • Studies do not show increased risk of rupture or morbidity for mother or baby.
    • Studies are limited, but a low vertical incision should not rule out VBAC given the current information.
  • “Unknown” previous uterine incision should not rule out VBAC. The two large studies done at large tertiary hospitals show that there is no increase in rupture rates or morbidity, and success rates are similar. Unless there is a high clinical suspicion of a complicated previous uterine incision TOLAC should not be ruled out.
  • Twins Gestation:
    • In all studies available it is shown that in women with a previous low transverse incision there is no increase in risk to VBAC a twin gestation.
    • Success rates are similar to those of singleton mothers. Twin gestation should not rule out TOLAC.
• How does management of labor differ in a VBAC? (p5)
  • Induction of labor for maternal or fetal factors remains an option for TOLAC. However, the increased risk of rupture that comes with any induction and the decrease in success rates should be discussed.
  • One large study of over 20,000 women found that rupture rates increased slightly with induction. Spontaneous labor had a 0.52% rupture rate, non-prostaglandins induction with a 0.77% rate, and with prostaglandins a rate of 2.24%. However, again the types of rupture were not specified and the context of the inductions are not known (unfavorable cervix, need for multiple induction methods, etc).
  • Another study of over 33,000 women found a slight increase in rupture (o.4% for spontaneous labor, 0.9% for augmented labor, 1.1% for oxytocin alone, and 1.4% with the use of prostaglandins). An analysis of this same study noted an increase in rupture rates when the highest levels of pitocin were reached, however no upper level of dosing has been decided for VBACs.
  • Studies done on the risks of misoprostol (cytotec) show an increase risk of rupture and should not be used for TOLAC. (Actually, it increases risk of rupture in ANY mother so it should not be used for induction, period.)
  • Due to the small absolute risk found in several studies, ACOG notes that use of pitocin for labor augmentation is not ruled out for VBAC.
  • Mechanical cervical ripening (such as the foley bulb) are also considered acceptable for labor augmentation/induction in VBAC.
  • ECV (External Cephalic Version), such as to turn a breech baby, are not contraindicated in a woman who wishes to VBAC.
  • Epidural/Analgesia use is not contraindicated and studies show it does not effect success rates. However, epidural use in general is shown to increase the chances of cesarean in all mothers. (to view that study, right click and select “copy link location” and input into google)
  • Electronic Fetal Monitoring is suggested since the main sign of uterine rupture is abnormal fetal heart rate (up to 70% of cases). It is noted that internal monitoring does not help in diagnosing ruptures.
• How should future pregnancies be managed after uterine ruptures? (p7)
  • If the rupture is in the lower segment of the uterus, the chance of another rupture is 6%. In the upper sections of the uterus it is around 32%.
  • ACOG suggests an elective cesarean for births after a rupture.
• How should women be counseled about TOLAC/VBAC?
  • Each woman will weight the risks and benefits differently. Therefore, the options should be discussed at length and documented.
  • Counseling should always consider the future plans for more children and discuss the risks of multiple uterine surgeries. Women should also consider that family plans can change or there may be unexpected pregnancies.
  • After counseling the ultimate decision should be made by the client. Global mandates (aka – hospital wide) should not be made as they do not consider the individual factors and wishes of each client.
• What resources should be available at a facility where a woman will VBAC?
  • The previous suggestion of ACOG was that VBAC should only be offered in facilities with “immediate” access to surgical facilities and staff. However, this severely limits the locations where women could VBAC.
  • ACOG now suggests that care providers and clients consider the facilities available, their individual risk factors, and the availability of other locations where more resources are available.
  • Health care providers and insurance companies should do all they can to facilitate women in achieving VBAC through transfer of care or co-management of care.
  • If there is no way to transfer care, a woman’s autonomy should be respected. If a woman wishes to VBAC in a hospital without immediate access to surgical facilities steps should be taken early in care to develop a plan of action in case of rupture.
  • It should be noted that coercion into a repeat cesarean is not appropriate. A policy of not allowing TOLAC at a facility should not be used to deny care or force a woman into a repeat cesarean. If appropriate, transfer of care should be arranged to a facility and care provider who is better able to support TOLAC.

Now I would like to take a moment to talk about the notion of only “allowing” VBACs in facilities with immediate access to surgical teams and facilities. Lets compare the risk of rupture, 0.7% in most studies, which is not always catastrophic, to the risk of other obstetric emergencies. Cord prolapse, a very dangerous situation in which the cord proceeds the baby down the birth canal and gets pinched, occurs in about 0.28% of births. This situation requires immediate access to a cesarean in most cases. Placental abruption, another very serious complication, occurs in about 0.7% of pregnancies. This also requires immediate access to cesarean in almost all cases. Notice that the risk of abruption and the risk of rupture are the same. The rate of shoulder dystocia, which is considered an emergency that may necessitate a cesarean (or an instrumental birth) is around 1.29% though some studies report it at higher rates in the current birth climate.

Now looking at the rates of these complications, which are on par with the risk level of rupture, we have to wonder why ALL hospitals offering birth services are not required to have immediate access to a cesarean. After all, placental abruption happens with the same frequency and can happen in any pregnancy and ACOG does not seem to be concerned that EVERY pregnant mother does not have access to immediate surgical care. At the end of the day, the risk/benefit analysis needs to be decided by the mother and what she feels comfortable with since the rate of rupture is comparable to the risks of any pregnancy and birth.

The point of this article is not to suggest any particular course of action for every mother. This is about giving you the facts to make your own decision. This is about looking at what ACOG really says about VBAC/TOLAC and not just what your doctor tells you they suggest. Arm yourself with information and consider your own personal factors and Birth Without Fear, no matter how you choose to birth.