Vaginal Birth After 2 or More Cesareans

by KMom

Copyright © 2000-2001 KMom@Vireday.Com. All rights reserved.

DISCLAIMER: The information on this website is not intended and should not be construed as medical advice. Consult your health provider.

CONTENTS

• Introduction
• Caveats
• Terms and Abbreviations
• Table of Studies
• VBAC after Multiple Previous C/S Success Rates
  • Table II:  VBA2+C Success Rates
  • VBA1C Rates Versus VBA2+C Rates
  • Factors Which Influence The Odds for VBA2+C
• Considering Uterine Rupture Risk
  • Cautions About Interpreting The Studies
  • VBA2C Studies and Rupture Rates
  • Discussion of Specific Rupture Studies
  • Does Pitocin Increase Risk of Uterine Rupture
  • The Influence of Other Factors on Uterine Rupture
  • Place Risks in Context
  • Minimizing the Risk of Uterine Rupture
  • Conclusion
• VBAC After 3 or More Cesareans
• Comparing the Risks of Repeat Cesarean vs. a Trial of Labor
• Emotional Factors in Considering a VBAC
  • An Opportunity for Healing
  • Healing Choices After a Previous 'Failed' Trial of Labor
• Increasing the Odds for a Safe and Successful VBA2+C
• References
  • VBA2C Studies
  • Other Relevant VBAC Studies
  • General References on VBAC
  • Processing Previous Births/Emotional Healing

Introduction

Is trying for a Vaginal Birth After Cesarean (VBAC) a reasonable option after you've had 2 (or more) cesarean sections?  Most authors conclude that it is, but many OBs are reluctant to consider it, especially recently due to a VBAC backlash movement.  Because many doctors have been reluctant to consider it, most medical literature and collections of VBAC stories have concentrated on VBAC after 1 cesarean (VBA1C).  There is an urgent need for information, analysis of medical literature, and stories of VBAC after multiple cesareans (VBA2+C).  

This websection analyzes the medical literature on the subject, the chances of success, the risk of rupture, and the emotional issues that may be involved, hints for healing, etc. There is another websection (VBA2+C Stories FAQ) that relates personal stories of VBAC after multiple cesareans.  It mostly contains personal VBA2+C stories others have decided to share, but it also has resources for finding VBA2+C stories in books and online. The VBA2+C FAQ and the VBA2C Stories FAQ are meant to be complementary and should be considered together. 

Readers are urged to do their own research in order to reasonably evaluate the various factors in VBAC vs. elective repeat c-section decisions.  There are many factors to consider in deciding.  Excellent VBAC information can be found online; readers are directed to the resources at www.childbirth.org/section/,  www.gentlebirth.org, www.ican-online.org, and the many medical journal abstracts available online at www.ncbi.nlm.nih.gov/PubMed/.  Be sure you understand what you are reading and the potential biases of the writers!  

Other valuable resources include the following books:

• The VBAC Companion, by Diana Korte
• Natural Childbirth After Cesarean, by Karis Crawford and Johanne C. Walters
• Birth After Cesarean: The Medical Facts, by Dr. Bruce Flamm

Further resources can be found in the References section of the VBA2+C Stories FAQ, as well as in the websection Great VBAC Resources on this site.

Caveats

The purpose of this FAQ is not to convince you that VBA2C is or is not the right option for you.  It is simply to gather together in one place more information about the difficult-to-find subject of VBA2C, and to explore its various issues, both medical and personal.   It is a detailed look at the research on VBA2C, an examination of the critical issues in the controversy, what research and anecdotal evidence shows on these issues, and important considerations if you do select a trial of labor.  It is not a short or quick introduction to the subject, so set aside some time for reading it thoroughly.  

It's important to remember that this is simply a sharing of information by and for health consumers.  Kmom is not an expert, not a professional researcher, not a medical professional, and she does not offer medical advice.  Although she has felt free to add in her opinions in the discussions of various VBAC controversies, these are certainly NOT medical advice, and are added simply for discussion's sake.  Readers should always be very cautious about any health information they get online (or indeed, anywhere else!).  Remember, YOU are the one ultimately responsible for your own healthcare decisions.  Be thorough in your researching, discuss the issues with your healthcare providers, and explore all your options before making decisions.  The purpose of this FAQ is not to offer medical advice.

Kmom is not entirely unbiased on the issue of VBACs; she has had 2 cesareans and then a VBA2C herself.  It was her search for information about the benefits and risks of a trial of labor after multiple cesareans that led to the creation of this FAQ.  However, although Kmom tends to favor VBACs and shares her opinions on this in this FAQ, she has tried to clearly label her opinions as such, and has tried to represent all sides of the VBAC issue fairly.  She strongly feels that each woman must consult her provider, look at the research for herself, examine her own birthing priorities and circumstances, and then decide for herself what is best in her situation. No criticism of either choice of birth mode should be inferred. 

The focus in this websection is primarily on VBAC after 2 c-sections because that is what most of the medical literature deals with and because few women with 3+ c-sections are given the opportunity to even try a VBAC.  However, that does not mean that VBAC after more than 2 c/s is inappropriate, impossible, or has never happened.  In fact, quite a number of women have had VBACs after 3 or more cesareans (VBA3+C).  Unfortunately, it's not well-studied in the literature, and official study sizes are small (although there is some data, which is presented here).  Therefore, most of the information in this FAQ will necessarily deal more directly with VBA2C, but whenever specifics are available on VBAC after 3 or more c/s they are given, and these stories are also included on the VBA2+C Stories FAQ.  

Finally, Kmom would particularly like to note that she strongly dislikes the terms, "Trial of Labor" (or the British alternative, "Trial of Scar") and "Attempted VBAC".  It implies being on trial, a pass-fail 'test', a judgment, a tentative attempt.  Kmom's personal opinion is that a labor after previous cesarean should be viewed and treated like any other labor. Kmom particularly dislikes the terms "failed trial of labor/failed VBAC".  This is NOT a failure.  However, this is the terminology used by the medical studies reviewed in this FAQ, and often even in VBAC books.  Alternative terminology is cumbersome and not standard, so Kmom has reluctantly utilized these terms in this FAQ.  Readers should be aware that its usage herein does not constitute approval!  Words can matter, and obstetrics is full of misogynistic and condescending terms as it is.  We can use these terms for ease of use and because it is standard, but we should also be aware of the weaknesses and subtle underlying implications of it.

Terms and Abbreviations

Reading a Frequently Asked Questions list (FAQ) about childbirth issues is often like negotiating a minefield full of unfamiliar terms and abbreviations.  Because it was not practical to write out each term each time, the following is a brief guide to the terms and abbreviations you might see in these particular FAQs.   

• ACOG - American College of Obstetricians and Gynecologists
• asynclitic - when the baby's head is slightly tilted to one side in utero; tends to make labor stall and/or be more painful.  Many so-called cases of 'CPD' are actually due to baby malposition; the baby cannot fit through the pelvis well *in that position* (but might well fit fine if the position were fixed)
• augmentation - the woman's labor starts on its own but at some point labor-stimulating drugs are added for various reasons such as FTP, etc.
• CPD - Cephalo-Pelvic Disproportion, where the baby is allegedly too large to fit through the mother's pelvis (rarely absolutely true; relatively speaking may be true if you consider the baby's position--baby may not fit through in that position or situation but it doesn't necessarily mean that it could not fit if more properly aligned) 
• c/s - Cesarean Section
• dehiscence - incomplete or asymptomatic separation of some of the layers of the uterus (does not go all the way through the uterine wall); generally has no implications for mother or baby's health.  Other names include 'scar separation' or 'uterine window'; sometimes the terms are incorrectly used as interchangeable
• direct-entry midwife - a midwife that goes straight into midwifery training first (as opposed to nurse-midwives, who generally become nurses first).  Direct-entry midwives usually practice in birthing centers or attend home births. There are many types of direct-entry midwives (DEMs) and terminology can be inconsistent.  Some midwives are Certified Professional Midwives (CPMs--certified through a national midwifery organization), others are Licensed Midwives (if their state licenses midwives), and others are lay midwives (without specific licensing or certification programs).  Most DEMs go to midwifery schools, most of which are extremely rigorous, but a few midwives are still trained through apprenticeship. Many people assume that nurse-midwives are more well-trained, but the main difference is how they got into midwifery training and where they attend births.  Although it varies from midwife to midwife, DEMs generally use less intervention, have the lowest cesarean rates, and the highest VBAC rates.  They also tend to be less accepted by the traditional medical establishment.
• ERCS - Elective Repeat Cesarean Section
• FTP - Failure To Progress, where dilation stalls or labor does not progress fast enough in the provider's opinion.  Often FTP and CPD are used interchangeably, i.e. the labor stalls because the baby cannot fit through the pelvis in that situation.  Overall term is "labor dystocia"
• grand multips - mothers who have had at least 5 or more pregnancies before; these mothers are also at increased risk for uterine rupture
• HBAC - Home Birth After Cesarean
• induction - starting a woman's labor with artificial drugs
• IUPC - IntraUterine Pressure Catheter, a device many early VBAC studies mandated to help monitor the uterus of the VBAC mom in hopes that it would help detect rupture earlier.  This requirement has been dropped by most providers these days.
• low transverse scar - side-to-side "bikini cut" scar done on the lower uterine segment where the uterus is least likely to experience a rupture
• low vertical scar - up-down scar done only in the lower uterine segment; some surgeons believe it is somewhat more risky than bikini cuts but current data seems to show similar risk to bikini cuts
• LUS - Lower Uterine Segment; the lower part of the uterus near the pubic bone that thins somewhat during labor.  Some women have been told during a repeat cesarean that their Lower Uterine Segment was very thin and might thus be more prone to rupture; whether this has any clinical value is unknown.
• morbidity - injuries/ health problems (short of death) caused by a procedure
• mortality - death caused by a procedure
• multips - mothers who have already had at least one child
• nurse-midwife - short for CNM, Certified Nurse-Midwife.  These midwives had nurse's training before going on and specializing in midwifery.  They often practice in conjunction with OBs, have hospital privileges, and can utilize many interventions such as epidurals, etc.  Some also practice at free-standing birth centers and a few do home births.  They generally have very good acceptance in the medical community, but the certification process has made it difficult for them to practice outside of strictly controlled settings and they sometimes face limitations on their protocols.  They also tend to be more interventive as a group than direct-entry midwives.  They do have 2.8x the VBAC rate of OBs, and can be an excellent choice for women who prefer hospital birth.
• PGE1 - Prostaglandin E1 (pill) used off-label in pregnancy to ripen cervix and induce labor; it is supposed to be an ulcer medication.  Generic name misoprostol, trade name Cytotec.  Different than PGE2!
• PGE2 - Prostaglandin E2 (gel or insert) used to induce labor/ripen cervix; trade names Prepidil or Cervidil
• pit. - pitocin, trade name for synthetic oxytocin; used to induce (start) or augment (strengthen) labor contractions
• placenta accreta or placenta percreta - placental attachment disorder where the placenta grows through the uterine wall and sometimes even into the mother's bladder; can necessitate hysterectomy or even cause maternal death.  Although the absolute numerical risk is fairly small, it does occur MUCH more often in women with prior cesareans, and the risk does increase somewhat with each subsequent cesarean. 
• placenta previa - low-lying placenta; may be covering the cervix completely or only partially.  Complete placenta previa needs a cesarean; partial previa may or may not need a c/s.  Placenta previa and other placental disturbances are much more common after prior cesareans; risk increases with the number of c/s.
• posterior - baby malposition where the baby is facing 'sunny-side up', or face towards the mother's stomach (also called OP); tends to make labor stall and/or be more painful.  Many so-called cases of 'CPD' are actually due to baby malposition; the baby cannot fit through the pelvis well *in that position* (but might well fit fine if the position were fixed)
• primips - first-time mothers
• scar separation - another name for dehiscence; thinned area of uterine wall. Proper name is dehiscence
• TOL - Trial of Labor (see note above); in some literature this is called 'trial of scar'
• unknown scar - when the type of uterine scar is not known
• uterine rupture - complete separation or tear that goes all the way through the uterine wall; a serious complication that if not addressed quickly can cause death for baby and perhaps necessitate a hysterectomy for the mother
• VBAC - Vaginal Birth After Cesarean
• VBA2C - Vaginal Birth After 2 or more Cesareans (other variations include VBA4C, VBA2+C, etc.)
• vertical scar/"classical scar" - up-down scar from near navel to pubic bone; all c/s used to be done this way but vast majority today are done with low transverse incisions, which is safer.  A classical scar is more likely to rupture than a low transverse.  A third type is a "low vertical" scar, which is up and down but only in the lower uterine segment.  This is also less likely to rupture.

Table of Studies

The following are the main VBA2+C studies available.  Details are included from the full paper on the study, except in the cases where the original is not in English, in which case information from the abstract is used instead.  Not all studies offer full information in every category, so some columns are left blank.  A few studies had typos or inconsistent statistics; these are indicated with a "?".  

The table is limited to studies that were done after about 1979 because before then authors often mixed low transverse incisions in with classical incisions, thus obscuring the risk.  Also, laboring conditions and protocols were so different then that comparisons are difficult.  Too many of those studies involve women with classical cesareans (which have a higher rupture rate), heavy use of drugs, forceps, and other highly interventive protocols which obscure the data.  Therefore, only studies under more 'modern' laboring conditions were used so comparisons would be more valid.  

Be aware, though, that even some of these 'modern' laboring conditions are rather questionable and may have impacted VBAC success rates and rupture rates.  Studies done in the 80s tended to have great restrictions on laboring moms, including mandatory IVs, internal monitoring, Internal Uterine Pressure Catheters (IUPCs), flat-on-back labor position and stirrups for pushing, sometimes urinary catheters, and strict adherence to very rigid labor curves.  They tended to have lower and much more cautious use of oxytocin and other induction agents.  

Studies in the 90s, on the other hand, tended to loosen up many of the uptight restrictions on VBAC moms from the 80s, but used oxytocin and other very strong labor drugs for induction and augmentation much more freely.  Now that the new century is here, oxytocin and other drug use is being looked at with more caution, since some studies suggest its overuse can strongly increase rupture rates.  So although these modern studies are more comparable than studies from before 1979, they still cannot be compared exactly, since labor protocols vary greatly between facilities and evolve over time. 

Here are the major VBAC studies with VBA2+C data in them that were used for this FAQ. 

Table I: VBA2C Studies

VBAC after Multiple Previous C/S Success Rates

Contrary to what many doctors will tell women, most VBA2C studies have found very good success rates in women undergoing a 'trial of labor' after 2 or more previous c-sections.  Success rates, of course, depend on the study, with some VBAC rates as low as 45% and others as high as 90%. That's quite a range of success rates---so why the wide range?  There are a number of factors that influence the VBAC success rate, including the purpose of the study, the protocols of the study, the choice of provider, how much intervention is used, etc.  

Studies designed to help promote VBAC or lower overall cesarean rates will have higher success rates (70-80%) than those that simply reflect the overall rate of VBACs in the general population (success rates in these studies tend to average about 45-65%).  Also, the protocols of the study influence the success rate; studies that use a high rate of inductions have documented that VBAC rates are generally lower when labor is induced.  Furthermore, the choice of provider can influence the rate of VBAC success; nurse-midwives often have higher rates of VBAC success (about 2.8x the national average) and direct-entry midwives probably have even better rates.  Other studies have shown that some OBs have a very low rate of c-sections in general while others have a very high rate indeed; it is logical that OBs with a low c/s rate will probably have a higher VBAC rate overall than OBs who are quick to resort to surgery.

So VBAC success rates will vary widely depending on the purpose of the study, the type of providers in the study, the protocols of the study (including the rate of induction), and the personal cesarean rate/philosophy of the individual providers in the study.  These varying success rates are summarized as following. Only studies in which it was possible to determine success rates specific to VBA2+C were included here.

Note: Be aware that some of these totals may not reflect the numbers given on an abstract or in the first glance at a study, which may only quote the rate for all VBACs instead.  Because of this, some totals had to be derived from data in the full text of studies in order to get success rates for ONLY VBA2+C.  These are the totals reflected below. 

Table II:  VBA2+C Success Rates

*(overall average for 2 or more c/s)

**It is unclear whether the Phelan 1987 and Phelan 1989 studies have duplicate subjects (like the Flamm 1988 and 1990 studies do).  Because it cannot be determined for sure, they have been assumed to be separate.  If there are duplicates, the totals given below would be thrown off somewhat but not by a great deal.  The averages below should still hold with little variation.

*** (VBA2+C rate for second half of study only; first half reported in Flamm 1988)

***info from abstract, which only specifies a 70% VBA2C success rate after induction with PGE2 gel.  Because the number of TOLs and number of VBACs are unknown at this time, the success rate only was considered in averaging success rates; the data was not figured into the total number of known VBA2+C TOLs.

Since these VBA2+C rates vary from 45% to 90%, it's hard to generalize what individual VBA2+C chances might be, so it is helpful to come up with an average VBA2+C success rate.  There are two ways to derive this number.  The first is to add all the VBAC rates together and average them (giving each study equal weight).  The second is to count up the numbers of actual VBACs and divide it into the numbers of actual trials of labor.  This latter method might be more accurate, given that some studies are extremely large and some extremely small, and their success rates should probably not be weighted equally.

If you weight each study's success rate equally, it averages to a rate of about 71%.  If you go strictly by numbers alone, there were 3999 trials of labor after 2 or more previous cesareans, and 2868 had VBA2+Cs.  This gives an average 72% VBA2+C rate.  So it is safe to say that the average VBAC success rate after 2 or more previous cesareans is about 71-72%.  Whether you use the 71% or 72% number, this is only slightly lower than the generally accepted VBA1C average of ~75% in VBA1C.  In other words, if you choose a trial of labor after 2 or more previous cesareans, you have an almost 3 in 4 chance of having a VBA2+C.   Those are pretty good odds. 

VBA1C Rates Versus VBA2+C Rates

Many providers delight in telling women that their chances for a VBA2C are lower than after 1 previous cesarean; even ACOG states this.  However, this depends on the study.   Porreco (1983) found an 81% VBA2C rate, versus an 85% VBA1C rate.  Phelan 1987 found an 73% VBA2+C rate, vs. a 82% VBA1C rate average. Similarly, Phelan 1989 found a 69% VBA2+C rate vs. a 83% VBA1C rate.  Cowan (1994) found a 77% VBA2C rate (79% 2+C) vs. an 81% VBA1C rate. Caughey (1999) found a 62% VBA2C rate vs. a 75% VBA1C rate.  Miller (1994) found a VBA2+C rate of 75% versus a VBA1C rate of 83% and emphasized the "decreased likelihood of success" in trials of labor after multiple previous cesareans, conveniently ignoring that 75% means that 3 out of 4 had a VBA2C anyhow, and that this is a higher rate of success than many VBA1C trials!  Asakura (1995) found a 64% VBA2+C rate compared with a 77% VBA1C rate, BUT noted that the VBA2+C rate had risen to 74% by the end of the study period, nearly equal that of the VBA1C rate.  

While some studies found a lower VBAC rate after multiple cesareans than after one prior cesarean, other studies actually found an increased rate of VBACs in those with multiple prior cesareans. Saldana (1979) found a pitiful 39% VBA1C success rate, whereas the population with 2 or more cesareans had a 58% VBA2+C rate. Stovall (1987) found a 75% VBA1C rate, whereas the rate was 79.5% for VBA2C and 100% for a small VBA3C group (or an 84% average for VBA2+C).  Novas (1989) found a 71% VBA1C rate, versus an 81% VBA2+C rate average.   Chattopadhyay (1994) found a much higher VBAC rate in the group with 2 cesareans, 90% vs. 54% for VBA1C.  And Flamm (1988) did not find a significantly different VBAC rate among those with 1, 2, or 3 prior cesareans.  

Many women report that doctors consistently underestimate their chances for VBAC after multiple prior cesareans.  Indeed, Davies (1996) found that while the obstetricians interviewed in their study estimated VBA1C rates at their hospital quite accurately, they consistently underestimated VBA2C rates.  Their estimates of VBA2C success ranged from 0-70%, with the average guess at 44%.  In fact, although only a few patients at their hospital tried VBA2C that year, 60% did succeed.  And the above analysis shows that VBA2C success rates actually average about 71-72% overall. The problem is that few doctors know it.  

So VBA2+C rates are not necessarily lower than VBA1C rates; it depends on the study looked at, and probably on the specifics of the factors that typically influence VBAC rates.  

Factors Which Influence The Odds for VBA2+C

There are many factors which influence VBAC success.  OBs have been studying them in order to try and predict 'who would most benefit from a trial of labor'.  However, they have found that while they can often predict women who are MOST likely to have a VBAC, large numbers of women who are NOT predicted to have a VBAC end up having one anyhow, despite their providers' lack of confidence. 

Jakobi (1993) found that 67% of women that were predicted  not to have a VBAC ended up having a VBAC anyhow.  If 2/3 of the women they predicted would 'fail' at VBAC ended up proving them wrong, obviously you should treat any statement that your chances of VBAC success are very low with significant suspicion.  While they can often predict VBAC 'success' with some degree of accuracy, authorities have not found any reliable way to predict VBAC 'failure' and are often wrong.

The following are factors that may influence the odds for VBA2+C.  However, again, keep in mind that while some factors may increase your odds for VBAC, no factor can reliably be used to predict VBAC 'failure'.   The fact is that many women do go on to have a VBA2+C, even when the 'odds' are seemingly against them (Kmom did!)  

Previous Vaginal Birth

Doctors have long noted that women who have had vaginal births as well as cesarean births tend to have higher rates of VBACs.  Several VBA2C studies also noted this (Porreco 1983, Phelan 1989, Hansell 1990, Chattopadhay 1994, Asakura 1995).  However, women who have never had vaginal births also have a good rate of VBACs.  In Phelan 1989, 2/3 of women (67%) who had never given birth vaginally went on to have a VBA2+C, and in Asakura 1995, 66% had a VBA2C. In Chattopadhyay 1994, 83% of those who had never had a previous vaginal birth went on to have a VBA2C.  

Thus, even if you have never had a vaginal birth before, your chances of VBAC are still good. Although a prior vaginal birth or even a prior VBAC is no guarantee of a VBAC, it does significantly increase the odds. Even so, most women with no prior vaginal births do go on to have a VBAC.

VBA2+C Rates By Primary Indication for Cesarean 

Studies have documented that the highest VBAC rates come when the first cesarean(s) occur for non-repeating reasons, like a breech position in the first c/s and then an automatic repeat c/s the next time, or fetal distress in the first c/s plus an automatic repeat c/s, etc.  The VBAC rates in these cases are often >80%.  

VBAC rates do go down somewhat when the reason for the original cesarean was CPD (so-called 'Cephalo-Pelvic Disproportion'), Failure to Progress, 'labor dystocia', 'arrest of labor', etc.  However, even in these cases, the chances are still as good for a VBAC as they are for a repeat c/s after TOL, usually much better.  Nor does prior cesarean for CPD seem to increase the rate of uterine rupture (Phelan 1987, Stovall, 1987, Tahilramaney 1984, Rosen 1991, Leung 1993, Rageth 1999). 

Some doctors insist on pelvimetry (measuring the pelvis manually or by x-ray) after a CPD cesarean in hopes of being able to predict whether a VBAC is likely or not, but studies show this does not reliably predict vaginal birth.  Pelvimetry is a static measurement and does not take into account the changes in the pelvis and the molding of the baby's head that occur during labor and birth, both of which can significantly increase the room there is for baby.  

Many women predicted (via pelvimetry) to have 'inadequate pelvises' and to need future CPD cesareans go on to have VBACs anyhow (Goer, Obstetric Myths vs. Research Realities). For example, Thubisi (1993)  found that 55% of women in the TOL group judged to have an 'inadequate' pelvis by postpartum x-ray pelvimetry had a vaginal birth anyhow.  If more than half the women predicted to have inadequate pelvises birthed vaginally, pelvimetry is not useful and may be harmful.  The authors called x-ray pelvimetry 'not necessary' for TOL, and noted that "it increases the caesarean section rate and is a poor predictor of the outcome of labor."

Other OBs have tried to determine other ways of determining true CPD, including strict interpretations of stalled labor parameters.  O'Herlihy (1998) found that only 84 women out of 42,793 actually met these strict criteria for 'true' CPD when carefully reviewed.  40 of these women with 'strictly defined' CPD had a TOL, and 68% birthed vaginally, 7 with larger babies.  15 of these 40 women had had a c/s at full dilation (10 cm) previously, yet 73% went on to birth vaginally with no serious maternal or neonatal problems.  They concluded that even strict definitions of CPD should not be used as an automatic 'recurrent' indication for ERCS.

In addition, many cases of past 'CPD' are actually caused by baby malposition, which may not recur in subsequent pregnancies and can often be prevented as well (see below).  And many VBAC moms have given birth vaginally to babies even larger than their 'CPD' baby as well.  Since pelvimetry and even strictly defined CPD diagnoses are poor predictors of future birthing modes, most authorities feel that women with prior cesareans for CPD should not be denied a TOL, unless there is gross malformation, previous serious pelvic injury, or extreme malnutrition.  

In women with one previous cesarean for CPD, the VBAC rate ranges widely.  It averages around 66% or so most often  (Goer, ibid), but sometimes goes as high as 80% (Cowan 1994). And many women have had VBACs after 2 previous cesareans for CPD (see Phelan, 1987, below), have had VBACs after previous 'failed' trials of labor, and have had VBACs after dilating completely and pushing both times (Kmom did!).  The following studies specifically examined VBA2+C rates after 1 or more cesareans for previous CPD/FTP.

Table III:  VBA2C Rates After Previous Cesarean for CPD

So although VBAC rates are highest in the face of non-repeating c/s indications (like breech, fetal distress, etc.), VBAC rates after so-called 'repeating indications' like CPD are still generally quite favorable.  Many women even give birth vaginally to babies that were bigger than their original 'CPD' babies (something that should not happen with a real case of CPD), and some women gave birth vaginally even after two previous cesareans for 'CPD' (Kmom did!).  Women who have been told that their pelvises are 'too small' or that they can only have a VBAC if their next baby 'is much smaller' should understand that these diagnoses are dubious at best.

Macrosomia

For many years, it was thought that a big baby (macrosomia, usually defined as >4000g or roughly, babies 9 pounds or larger) would tend to distend the uterus too much and thus predispose it to uterine rupture, so a trial of labor was regularly 'prohibited' among women with babies suspected to be big.  One study (Aboulfalah 2000) did find an increased rate of rupture, but apparently did not control for pitocin use, and since many OBs still use induction for suspected macrosomia, this might be a possible cause of the higher rate.  Most studies, on the other hand, have repeatedly not found higher rates of rupture with macrosomic babies (see Flamm in Birth After Cesarean, Tahilramaney 1984, Leung 1993, Rageth 1999).  A big baby probably does not predispose to uterine rupture, and most authors now agree that a trial of labor should not be excluded on this basis.

Because of the past policy of exclusion, there is little data to be found regarding macrosomia and VBA2+C.  Even so, it is probably not reasonable to exclude women with multiple prior cesareans from a TOL when there is suspected fetal macrosomia. In particular, given the tremendous false positive rate in predicting macrosomic babies (predicting macrosomia is only slightly more accurate, on average, as flipping a coin), macrosomia should probably not be a factor in deciding whether women with multiple prior c/s should have a TOL.

VBAC success rates with macrosomic babies do tend to be somewhat lower than with average-sized babies. Most doctors would say that the rate is lower simply because big babies may be 'too big' to fit through the mother's pelvis.  However, the rate of women who have had cesareans for "CPD" and then gone on to VBAC babies even larger than their "CPD" baby (see above) suggests that this view is too simplistic.  Instead, there are probably a number of different factors at work. 

First, it's possible that if larger babies have less 'wiggle room' than smaller babies, it may make birth a little harder to negotiate.  This may be especially true if the baby is in a less-than-optimal position (i.e., a hand by the face, head tilted to one side, or face towards mother's abdomen instead of towards her back), where a larger size may make it more difficult for baby to fit through the pelvis or to readjust its position so it can come out easier.  Many women with primary cesareans for "CPD" find that baby malposition was the problem, and this may have been harder to resolve with a larger baby.  Many of these women find that by preventing malposition from recurring (see FAQ on Baby Malposition), they can go on to have a VBAC. 

Second, physician bias and protocols for macrosomic babies may also account for lower VBAC rates.  Research clearly shows that if doctors even suspect a larger baby, labor is managed differently and a higher c/s rate results, whether the babies are actually bigger or just average-sized (Leaphart 1997; other references in Macrosomia and Induction FAQ).  Doctors may create self-fulfilling prophecies with large babies by expecting problems, and may create higher c/s rates by regularly employing more induction and other intervention with larger babies.  The VBAC rates for macrosomic babies may not have to be lower, but may instead simply reflect the biases and overly interventive protocols used by most doctors with cases of suspected macrosomia. 

Third, a common tactic when macrosomia is suspected is to induce labor early in hopes of reducing the chances of a cesarean and avoiding the shoulders getting stuck (shoulder dystocia).  Yet non-VBAC studies show inducing early for macrosomia often actually increases the rate of cesareans (sometimes to more than 50%). VBAC studies also show that induction for macrosomia increases the c/s rate, decreasing the VBAC rate strongly. In Rageth 1999, the VBAC rate dropped from 74% down to 57% if mothers were induced for macrosomia. Although the sample size was extremely small, Leaphart 1997 found that induction for macrosomia dropped the VBAC success rate from 71% down to 29%. Other data seems to confirm that induction in general tends to lower VBAC success rates (Davies 1996, among others), and may increase the risk of rupture (Zelop 1999, Rageth 1999, Ravasia 2000). Furthermore, in some non-VBAC studies, induction was even associated with a higher rate of shoulder dystocia, yet another  reason to avoid it (see Macrosomia and Induction FAQ for references).  

However, even with all of these possible limitations, VBAC still occurs the majority of the time when macrosomia is present. None of the VBA2C studies analyzed for this FAQ examined macrosomia as a variable for VBAC success, but in VBA1C studies, VBAC success rates with macrosomic babies ranged from 55% (Holt 1997, Flamm 1989) to 64% (Davies 1996, Aboulfalah 2000) to 70% (Abbassi, second 1998 study).  Some of these were undoubtedly induced, so it's possible that by having women labor spontaneously instead, the VBAC rates with macrosomic babies might be even better.

With success rates at least 55%-70% and probably no increased rate of uterine rupture, a TOL with a macrosomic baby is a reasonable option.  Choosing a midwife that is comfortable with 'big babies', knows how to prevent or minimize potential risks like shoulder dystocia, and does not generally use induction for macrosomia may help increase the chances for a favorable outcome.

Baby Malposition

As noted above, many women with past cesareans for "CPD" or "FTP" have actually found that the problem really was baby malposition, a factor many doctors tend to ignore.  As long as the baby is head-down, most doctors (and even many midwives) pay little attention to fetal position.  However, if baby is facing the mother's tummy instead of her back (posterior instead of anterior), has its head tilted to one side (asynclitic), or has a hand/arm by its head (compound presentation or 'nuchal' hand/arm), labor problems often occur and baby can get 'stuck'.   Although some of these babies resolve their positions and are born vaginally, a high percentage of them end up with a c/s.  Some posterior babies can be born vaginally (usually those that are small and have their chins well-tucked), but many also end up with a cesarean.  In addition, labors with malpositions are often  long, hard, very painful, and especially difficult, making many of these mothers afraid to face a trial of labor again.

Because baby malpositions tend to place uneven pressure on the cervix, dilation often stalls, and the labor is labeled "Failure to Progress" (FTP).  Even if dilation finishes, the baby's less-than-optimal position often causes it to get 'stuck' (deep transverse arrest, or arrest of descent) and baby often doesn't descend into the pelvis much, so this is usually chalked up to a "too big baby" or a "too small pelvis" (CPD).   Not all cesareans for FTP, CPD, or 'labor dystocia' are caused by baby malposition, but many are.  And many women have gone on to VBAC by learning how to prevent malposition from recurring  (see the FAQ on Malpositions for specifics).  

The modern medical literature largely ignores the problem of baby malposition these days; most information is found in midwifery, doula, or nursing journals, in obstetric journals from non-English speaking countries (especially China), or in chiropractic journals.  Because of this, most OBs either are not exposed to the literature on malposition (and how to resolve it), or consider it much too 'alternative'.  Therefore, there is little mainstream obstetric data on malpositions and VBACs.  

One of the only studies that examines the question is the Rageth 1999 study from Switzerland.  It found that Fetal Malpresentation (either breech or posterior) was significantly correlated with VBAC 'failure', presenting nearly 4x the risk for a 'failed' TOL.  Only 42% of women with fetal malpresentation ended up with a VBAC in their study.  The picture improves somewhat if breeches are removed from the picture; 58% of those with posterior babies in the study did end up having a VBAC (compared to 74% VBA1C rates overall).  The study unfortunately did not specify how many of these babies resolved or did not resolve their posterior positions during the VBAC; this would be information that would be very helpful to know.  Some posterior babies are born vaginally, but most rotate to anterior and thus are able to be born vaginally.  Of those that start anterior and then rotate to posterior, many are born vaginally, though it is not an easy labor.  A very high percentage of those that remain posterior from the beginning to the end of labor ('persistent posterior') end up being born by cesarean.  So it would be interesting to know how many of the 58% of 'posterior' babies having a VBAC in the study had actually rotated prior to birth, how many actually emerged posterior, and how many were posterior from beginning to end.

If you think you may have had a cesarean due to a malposition problem, you should read Optimal Foetal Positioning by Jean Sutton and Pauline Scott, or The Labor Progress Handbook by Penny Simkin and Ruth Ancheta.  These are available from www.midwiferytoday.com, www.1cascade.com, or www.birthworks.org. Also be sure to read the FAQ on Malposition on this website for more details, documentation, and references.  Baby malposition CAN affect labor and cause cesareans or 'failed' TOLs, but they do not have to.  There are steps that can be taken to prevent malpositions, or to fix them if they do occur.  (Kmom's stories are a good example of the influence of malpositions!  See below.)

VBA2+C Success Rates and Pitocin Use

Routine use of artificial oxytocin (trade name, pitocin) also tends to decrease chances at VBAC.  Augmentation (adding pitocin after labor has already started spontaneously) tends to impact VBAC rates less than induction (starting the labor from scratch with pitocin or other induction agents), though not always.  Although not all studies have found pitocin use to lower VBAC rates, and although pitocin can be valuable in selected cases when used cautiously and judiciously, many studies have found lower VBAC rates (and sometimes higher dehiscence and rupture rates, see below) when pitocin is used.  

Lower VBAC rates with pitocin use is true for both VBA1C and VBA2+C.  For example, Davies (1996) found that among VBA1C patients, those who were induced had a 42% VBAC rate, whereas those who were not induced had an 88% VBAC rate.  They concluded that "induction of labor in patients attempting vaginal birth after cesarean should be performed only when absolutely medically indicated.  In those patients without a strong medical indication for induction of labor, awaiting the spontaneous onset of labor is recommended."

Looking at only VBA2+C studies, the association between pitocin use and lower VBAC rates also seems to generally hold: 

Table IV:  Influence of Pitocin on VBA2+C Success Rates

Although not all VBA2+C studies showed a negative effect from oxytocin use (i.e. Granovsky-Grisaru 1994, Chattopadhyay 1994), many studies do (including plenty of VBA1C studies).  Enough studies have documented lower VBAC rates when pitocin is used that the possible advantages and disadvantages should be considered most carefully before a decision is made.  In some cases, careful use of pitocin might help achieve a VBAC, but its routine or aggressive use should probably be avoided.  (See discussion below on pitocin and rupture risks.)

Emotional Homework

Although little scientific data is available on it, many providers and VBAC moms find that emotional processing is an important part of VBAC preparation and may help increase VBAC success.  Although some cesareans are due to purely physical circumstances or mismanagement, many women find that there is an emotional component that may have contributed to their cesareans.  Lack of body trust, a past background of abuse, an over-reliance on or reluctance to question medical authorities, a feeling of helplessness or over-passivity, a prior loss of a baby (due to circumstances like miscarriage, stillbirth, abortion, adoption, etc.), control issues, exaggerated fears of pain in labor, past history of difficult birth in the family, etc. are all factors that can affect a woman's ability to birth freely and without excessive anxiety or intervention. This is such an important issue that an entire section is devoted to it below (see  "Emotional Factors in Considering a VBAC"), and resources for further information are given.

Contrary to what many doctors believe, birth is not a purely mechanical process.  Emotions can and do influence the process of birth, and doing 'emotional homework' before labor can help the process along.  Many women who have had prior cesareans or even one 'failed' TOL found that they had unresolved or deeply troubling issues that weighed on them and may have contributed to the c/s.  Many have found that delving deeply into their emotional 'homework' before the next labor helped them towards a more satisfying birth, however it unfolded.  It is Kmom's opinion that 'emotional homework' is one of the MOST important things you can do to prepare for a better birth.

Professional Labor Support

Many women find professional labor support (in addition to labor coaching from their partners/husbands) to be invaluable.  These are women who are professionally trained to provide extra labor support, in whatever way you need.  These women, usually called 'doulas', receive professional training, generally work for between $200-$500 (depending on your area), and can be found through organizations such as DONA (Doulas of North America, www.dona.com), Birth Works ( www.birthworks.org ), or  ALACE (Association of Labor Assistants and Childbirth Educators, www.alace.org).  If you cannot afford a doula, many are willing to barter or negotiate for their services, or you can ask for a doula-in-training, as they must attend a certain number of births in order to certify and may be willing to come to your birth for free or for a greatly reduced fee.

Some of the many things that doulas do include (adapted from a doula brochure from Cutting Edge Press, www.childbirth.org/CEP.html): 

• Doulas stay by the mother's side throughout the birth, providing continuous support and encouragement
• Doulas provide emotional support and comfort techniques
• Doulas recognize birth as a key life experience and help women prepare and carry out their plans for birth
• Doulas support the father while he supports the mother; they help father participate with confidence
• Doulas seek to cultivate a positive birth memory for the mother
• Doulas assist in dealing with a difficult labor by suggesting labor support coping strategies
• Doulas help the mother and her birth partner understand the labor process
• Doulas strive to work as a team with the nursing and medical staff

Sometimes parents are reluctant to hire a doula because they are afraid she will usurp the husband's place in birth, make him feel less needed, detract from the intimacy of the moment, 'take over' the birth, or generally take away from the birth experience.  This is an understandable concern.  However, doulas are there to support both the father and the mother; childbirth is an emotional and physical rollercoaster for both parents, and many fathers are overwhelmed by the experience, especially if the birth becomes challenging at all.  A doula can provide a welcome additional source of support.

Many fathers who were unsure about hiring a doula later reported that their help was invaluable, that it did not detract from the experience at all but rather greatly enhanced it.  They appreciated the experience and 'labor tricks' that the doula brought to the birth, the ability to take an occasional break from labor to eat or go to the bathroom (without having to leave their wife alone or with strangers), the ability to be there emotionally for the mom but without the pressure of being mom's only support, and relief from the pressure of having to know everything about birth in order to keep all the interventions away.  Although many fathers fear that a doula would take away from their place in birth, fathers who have experienced a doula's help almost universally endorse it (Kmom's husband greatly appreciated it!).  

Although little information is available on doulas and VBACs, a meta-analysis of studies on doula use shows that their support can help cut the c-section rate by almost 50%!  Women who utilize doulas tend to have 25% shorter labors, less intervention (40% less pitocin!), and to need less medication (60% fewer requests for epidurals).  They also tend to have more success at breastfeeding, and feel more emotionally satisfied with their births.  (See the FAQ on Finding A Size-Friendly Provider for references.) Any woman who is considering a trial of labor should probably strongly consider hiring a doula if possible. 

Choose Providers Wisely

Another extremely important way to increase your VBA2+C chances is to choose a truly VBAC-friendly provider.  Many providers pay lip service to VBACs but do not truly support it, impose so many limitations that your chances are greatly reduced, or undermine it in subtle ways without realizing it.  You need to find out YOUR provider's c/s rate and VBAC success rate.  If your provider does not have a low c/s rate, does not have a high VBAC rate, or does  not have much experience with VBACs, you might want to consider another provider.

You should also consider what kind of procedures, routine protocols, and limitations on labors that your provider may insist on. These will tell you more about your chances for VBAC than any study. If your provider is not strongly supportive about a trial of labor for you, seems very fearful of or dwells a great deal upon uterine rupture, then perhaps you need a provider that is less fearful and knows that research supports TOL vs. ERCS.  Also, if the provider places lots of limitations on VBAC labors (must come in in early labor, must dilate a cm/hour even in early labor, mandatory continuous fetal monitoring, mandatory induction before or at term, etc.), you might want to consider finding a more VBAC-friendly provider to increase your chances for a VBAC.  

Certified Nurse-Midwives (CNMs) tend to have about 3x the rate of VBACs as OBs do, and Direct-Entry Midwives (DEMs such as Certified Professional Midwives, Licensed Midwives, etc.) probably have even better VBAC rates.  Because midwives tend to be more liberal in 'permitting' a trial of labor to a wider variety of women than many doctors, and because they tend to be much less interventive in labor and birth, your chances for a VBAC tend to be better with a midwife on the whole.  However, there are VBAC-friendly OBs, and there are 'medwives' that don't truly support VBAC or who are highly interventive.  A certain job title is not enough to guarantee that a provider is truly VBAC-friendly.  Important questions must be asked, with careful attention to the spoken and unspoken messages and beliefs of the provider.  

You should find out  each provider's overall c/s rate (including first-time c/s rate vs. repeat c/s), TOL rate (how many of patients with previous c/s have a TOL), VBAC rate (of those who have a TOL, how many go on to have a VBAC?), and how much experience the provider has with VBACs.  You will also want to know what routine protocols the provider uses for VBACs (see above).  Further guidelines and questions to ask prospective providers about VBAC can be found in VBAC books such as The VBAC Companion by Diana Korte, or Natural Childbirth After Cesarean by Crawford and Walters.

It is also often quite revealing to ask very open-ended questions about important issues such as when and how the provider uses induction, augmentation, monitoring, etc.  Providers often unconsciously tell women what they want to hear at the first interview, but seem to get more restrictive and nervous as the end of pregnancy approaches.  Many VBAC mothers have found what seemed like a VBAC-friendly provider, only to find many conditions, restrictions, and caveats placed on them near term ('you can only have a TOL if the baby is small', 'you can't go past due', 'the baby hasn't engaged yet, you'll need a repeat c/s', 'your cervix is not ripe yet, you'll never go into labor', etc.---NONE of which is supported by research as being important).  So many VBAC moms have experienced these seeming 'bait and switch' tactics (which may or may not be unconscious) that it is vitally important to get all of these issues clarified ahead of time.  

And remember, it is almost never too late to switch providers if you begin to have significant reservations about whether your provider really is the right one for your VBAC.  Providers really have quite a wide range of policies and attitudes about VBAC, even in the face of significant complications.  Although you may find the perfect person to support you in your VBAC, many VBAC moms have found that they have had to switch their care partway through a pregnancy, sometimes even very close to term.  A few women have even switched providers in the middle of labor! You owe it to your provider to listen carefully to their reasoning and consider their opinions; they owe it to you to provide you with research to back up their opinions, and time to discuss the issues adequately.  At that point, it is up to you to make a sensible and reasonable decision.  This might be repeat cesarean, going ahead with a TOL under certain guidelines, or switching to a new provider for a TOL without these restrictions.  Remember, YOU are the consumer, and YOU make the final decisions.   

Considering Uterine Rupture Risk

Is the risk of uterine rupture higher when a mother has had multiple previous cesareans?  This question is difficult to answer at this point because evidence is contradictory.  Preliminary evidence from the 80s and early 90s suggested that the risk of rupture was NOT greater for moms with 2 previous cesareans.  However, several studies published in the mid-to-late 90s found that while the risk was still small, there was some increased risk for rupture in women with at least 2 prior cesareans, and that the risk may go up as the number of prior cesareans increases.   

Previously, the American College of Obstetricians and Gynecologists (ACOG) supported a trial of labor in those women with 2 or more previous cesareans who wanted one.  Their latest revised recommendations still supports a trial of labor in these women but does not endorse it as strongly either.  And some doctors, always skittish about women with multiple previous cesareans, are now refusing to even consider a VBA2C.  However, at this time, most providers will still consider a VBA2C, but not all will be truly supportive or may place unreasonable restrictions on it.  Midwives are probably more likely to support a trial of labor after 2 (or more) cesareans, but some OBs and family doctors can still be found that will also offer a fair 'trial of labor' in this situation.

Despite the more recent studies that may show a somewhat increased risk of rupture with multiple cesareans, it's important to note that nearly every single study on VBA2+C--even the most recent---supports a trial of labor for 'motivated' women with more than one previous cesarean.  Even the study that found the highest rupture rates (Caughey 1999) still supports a trial of labor (with informed consent) for those who wish one.  

Cautions About Interpreting the Studies

So what exactly are the rates of rupture in women with multiple previous cesareans?  This is a very  difficult question to discern; there are no easy answers.  The rates of true rupture found in the medical literature varies from 0.0% to nearly 4%.  Most studies found no increase in rupture in those with multiple cesareans, while other studies found 2-5x the rate of ruptures.  However, keep in mind that even in the studies that found (gasp!) "a higher risk of rupture", the overall rate was still low, comparable or just slightly increased over rates of other unpredictable birth complications (see below).  

For example, Leung et al (1993) found that the rate of rupture was about 2% for women with 2 or more c/s, a risk 2.6x that of women with only 1 c/s.  After adjusting for various possible confounding factors, their analysis showed a 3.8x risk for uterine rupture in women with 2 or more c/s!  Yet they also cautioned readers to keep those numbers in perspective, since 98% of women with 2 or more c/s in the study labored and birthed safely.  Again, it is important to look at the whole picture when considering these numbers.  

In general there is a great deal of difficulty in analyzing uterine rupture studies because so many factors and definitions have to be considered.  True uterine ruptures are different than benign scar dehiscences, yet some studies do not separate out these and consider them together, resulting in very high-appearing 'rupture' rates.  Yet benign dehiscences have very little impact on labor and birth, are often discovered only accidentally, and rarely affect the health of either the mother or baby.  Most careful researchers make a definite distinction between true ruptures and benign dehiscences.  In the 90s, more and more researchers began considering only true ruptures when evaluating risks, since dehiscences seem to have little clinical relevance.  But because not all researchers draw careful distinctions like these, uterine rupture research can be misleading.

When you read abstracts listing dehiscence and/or rupture rates, it is important to know which they are referring to, and if possible to get the study so that you can confirm the numbers.  For example, Phelan 1989 says in its abstract that the overall rate of uterine dehiscence was 3%.   Some people would read this as a rupture rate of 3%, but actually the rupture rate in the study was 0.0%---there weren't any true ruptures in the study.   Even if you do want to consider dehiscence rates (and as noted, many don't anymore), the overall dehiscence rate in this study was 3%, BUT the rate in the TOL group was 1.8% vs. 4.6% in the ERCS group.  So if you read the abstract without full understanding or did not read the entire study, you might assume that this study had a rupture and/or dehiscence rate of 3%, when actually the dehiscence rate for the TOL group was 1.8% and the rupture rate was 0.0%.  That makes a LOT of difference!

Another factor to consider is the protocols that  women labor with in a trial of labor.  For example, excessive use of oxytocin (synthetic version: pitocin or pit.) is known to be a risk factor for uterine rupture, and several studies have connected it with many of the cases of uterine rupture out there.  Yet not all studies specify whether pitocin was routinely used in their trials of labor, what the dosage was, when it was started, how often the dosage was increased, etc.  Although some studies have found no increased risk with pitocin, other studies HAVE found an increased risk, particularly for induction.  

A number of cases of uterine rupture may have been preventable or the damage to babies more minimized.  Ruptures have been found in women who have had their labors induced or augmented with multiple labor drugs or high levels of pitocin, had epidurals (which may decrease the mother's ability to feel the abnormal pain of rupture), and/or were inadequately monitored because of staffing concerns or carelessness (often even after the mother complained that 'something was wrong').  Some recent studies have tied many cases of rupture to induction (especially use of multiple induction agents or induction with an unripe cervix), excessive use of pitocin, pitocin starting in the latent stage of labor, poor management of labor, or 'poor obstetric conditions'.  So although a certain percentage of ruptures may have occurred in a study, it doesn't follow that the same amount would occur in other populations automatically.  Some cases may be preventable.  

Labor protocols may also increase a patient's risk of rupture.  Because many doctors require that their VBAC patients have their labors induced early, that they have pitocin augmentation unless they dilate 1-1.5 cm per hour, have an epidural placed early in labor ("just in case"), or face other highly interventive protocols, the risk of rupture may be increased among these patients.  To compare these patients' risks of rupture to the risk faced by women laboring spontaneously and without interference or augmentation is unfair and 'stacked', yet most studies do so regularly.   Keep in mind that almost NO studies of any real size have researched the uterine rupture rate among women in spontaneous labor, with no pitocin or other drugs, etc.  We don't know what the 'true' underlying rate of rupture may really be. 

Also, rupture rates seem to have gone up over time (Farmer 1991, Leung 1993, and others), which seems to indicate the influence of other factors. In particular, the VBAC studies done in the 90s seem to have slightly higher rates of rupture overall compared to those done in the 80s, if considering only the rate of true rupture.  This may be because in the 80s when VBAC was a relatively 'new' concept, the candidates were selected more carefully and monitored more carefully, or because the rates of induction and augmentation with strong drugs vastly increased in the 90s (including in VBACs), or that the number of trials were small in the 80s and it took the larger trials in the 90s to reflect increased rupture rates, or a combination of all three factors. Thus it is very difficult to accurately compare rupture outcomes among various studies, and rates seem to vary widely.  However, even with these limitations, some comparison can be useful.  

VBA2C Studies and Rupture Rates

Among the VBA2C studies cited analyzed for this FAQ, the uterine rupture rate varied from 0.0% to 3.7%.  Rupture rates for trials of labor after 1 c/s vary greatly too, but generally run < or = 1%.  Of the VBA2C studies below, a number seem to have rates from 1-2%, although some are below 1% as well, and quite a few found NO ruptures at all.  Here are the VBA2+C studies that had rupture rate information specified in them.

Table V:  VBA2+C Rupture Rates (Low Transverse Scars)

* Note that the number of trials of labor in this table on VBA2C ruptures is different than the number of trials of labor in the table on VBA2C success rates.  This is because some studies specified only VBAC rates but had no information on number of ruptures or rupture rates, or vice versa.  Only studies in which specific numbers were available for each of these categories were included in the tables on those subjects.  This is why the number of trials of labor seem different on the surface.

If you add up all the data, there were 67 ruptures in 4,935 trials of labor.  That translates to a 1.4% rate of true rupture in VBA2+C trials of labor.  True rupture rates in VBA1C TOLs vary from study to study but generally average between 0.4% and 1%, so this does represent a somewhat increased risk rate (although please note that the risk of other emergency complications in labor is around the same or more--see discussion below).  With informed consent and an eye to reducing risks (and keeping in mind the very real risks of repeat cesarean sections and benefits of vaginal birth), women and their providers can still logically and reasonably choose a trial of labor after multiple prior cesareans.  And in fact, nearly every study also concludes that this is a reasonable choice.

It is VERY important to note that a number of the ruptures come from 'poor obstetric conditions' (Abbassi 1998, Asakura 1995), questionable aggressive management policies for VBAC or excessive pitocin use (Leung 1993).  While some studies examined the role of pitocin use, other large series did not (Miller 1994, which did have a higher rate of ruptures after multiple cesareans).  A number of the ruptures in the above studies were probably caused by injudicious management, plus at least a few ruptures were in women with 'unknown' scars (which might have been classical scars).  Keep in mind, therefore, that the 1.4% rupture rate may be artificially high.  

Although it is difficult to say for sure, it is quite likely that aggressive management and/or injudicious use of pitocin added to the number of ruptures, and that by avoiding these policies,  it is quite likely that the rupture rate in VBA2+C could be lowered.  However, what the 'true' rate of naturally-occurring rupture would be in VBA2+C is unknown.  It may or may not still be increased over VBA1C rupture rates.

Discussion of Specific Rupture Studies

Discussion of specific VBA2+C rupture studies is going to, of necessity, concentrate on the studies that did involve uterine rupture, which may give a mistaken impression that uterine rupture occurs more often than it really does.  So it's important to begin by emphasizing that the majority of VBA2+C studies found NO ruptures at all.  Many of these were small studies, it's true, but some were larger and would be expected to have at least some ruptures (and together add up to plenty of trials of labor which collectively should show some ruptures too).  That 13 studies found NO ruptures at all is quite encouraging.  The following studies found a 0.0% rate of true uterine rupture in their VBA2+C patients with known low transverse or low vertical scars:

• Saldana, 1979, n=38
• Porreco, 1983, n=21
• Martin, 1983, n=19
• Stovall, 1987, n=51
• Farmakides, 1987, n=57
• Phelan, 1987, n=159
• Pruett, 1988, n=55
• Flamm, 1988, n=89
• Novas, 1989, n=36
• Phelan, 1989, n=501
• Hansell, 1990, n=35
• Granovsky-Giru, 1994, n=26
• Chattopadhyay, 1994, n=115
• Davies, 1996, n=5

On the other hand, other studies have found some uterine ruptures in women with 2+ prior cesareans, as is inevitable.  That many of these studies fall in the mid-to-later 90s is an interesting coincidence. As noted above, perhaps the difference is simply that women who had a trial of labor were selected less judiciously as people became more relaxed about a TOL, that more pitocin or other drugs were used (and more aggressively, especially for induction or augmentation of early labor), or simply that a greater amount of subjects were used (which would have more power to detect overall rupture rates).  It will be interesting to see what rupture rates do in the future, although with the current very high rate of 'active management' techniques they may not go down at all.  

The following are VBA2+C studies in which uterine ruptures occurred and there is relevant information about these ruptures for discussion.  Further summaries of the studies can be found in the reference section.

Flamm 1988 was a multicenter study of VBAC TOLs in women with 1 (n=1687), 2 (n=82), or 3 (n=7) prior cesareans.  There were 3 true ruptures in the whole study, all occurring in women with one prior cesarean. 2 of the 3 ruptures occurred in women receiving pitocin augmentation in early labor (much like Leung 1993, see below).  There were no ruptures in the group with multiple previous cesareans.   

Flamm 1990 was a continuation of this same multicenter study, with data from 3 more years added on for a total of 5733 trials of labor over 5 years.  The overall rupture rate for the whole study was 0.2%.  About 29% of the TOL group received pitocin in their labors; the VBAC rate was 68% in the pitocin group versus 78% in the group without pitocin.  There were 10 cases of uterine rupture overall, 6 of which involved the use of pitocin (60%).  The rate of rupture in pitocin labors was 0.4% versus 0.1% in labors not using pitocin, although the difference did not reach statistical significance. 

In the Flamm 1990 study, 245 total patients had a TOL after 2 previous cesareans (89 of whom were apparently accounted for in the 1988 study).  Although there were no ruptures in the 1988 study in the multiple c/s group, there was at least one listed in this study (although the patient apparently had had 2 prior classical cesareans, which rupture more often, and had labored at home apparently without monitoring).  Although the authors don't specify the rupture rate in the multiple cesarean group, the authors do note that "the incidence of uterine rupture in this group did not differ significantly from that in the group of patients with one previous cesarean."  

Therefore it seems logical that this one rupture (after 2 apparently classical cesareans) was the only rupture in the 2+ c/s group, which probably means that there were no ruptures in the group with multiple low-transverse cesareans.  However, since this is all based in interpolation or 'guessing between the lines', the rupture rate for 2+ c/s is not included in the table above.  The important point from this study is simply that the rate of uterine rupture was NOT increased in the multiple cesarean group.

Phelan 1989 studied 501 women who had a trial of labor after 2 prior cesareans.  They found 0.0% true ruptures in the TOL group vs. a 0.2% rate in the group with elective repeat cesareans. They found a 1.8% dehiscence rate in the TOL group vs. a 4.6% dehiscence rate in the ERCS group.  57% of patients received some pitocin in labor, although the vast majority of this (94%) was from augmentation.  In those who received pitocin, they found that the dehiscence rate was significantly increased (2.1% vs. 1.4% in the group not receiving pitocin).  This translated into a 1.5x risk for dehiscence when pitocin was used.  Although this did not apparently impact ruptures, the trend towards increased risk for dehiscence with pitocin is notable.  

Leung 1993 came from the opposite pole and started with uterine ruptures, looking to see if any factors were more common in women with ruptures.  They studied 70 cases of uterine rupture out of 8513 trials of labor over a 7-year period (0.8% rupture rate). They found that the risk of uterine rupture was increased in those receiving an 'excessive amount' of pitocin (2.4x risk), those who experienced 'dysfunctional labor' (8.1x risk), and those who had a history of two or more cesareans (3.8x risk).  On the other hand, they found that macrosomia, epidurals, history of VBAC, unknown uterine scar, and history of c/s due to "CPD" were not associated with rupture.

Interestingly, the authors noted that the incidence of uterine rupture increased significantly over the years of the study (1983-1990).  They provided no further details, but it would have been interesting to know if the rate of pitocin use in VBACs had increased during that time.  This echoes the observation that the uterine rupture rate seems to have increased somewhat over time, although why is a matter of speculation at this point

The most interesting thing about the study was the amount of pitocin used and especially when and how pitocin was used.  77% of women who ruptured had received pitocin during the labor, a very high rate.  But most importantly, 2/3 of the women who ruptured had received pitocin in the early (or latent) stage of labor.  This raises the question whether aggressive 'augmentation' of early (latent) labor is really appropriate in VBAC moms.  

In the study, women without prior cesareans who had contractions but were in early labor could be sent home, whereas women with prior cesareans who had had contractions but were in early labor were not permitted to go home. In fact, 76% of women who eventually ruptured were admitted at < or = 3 cm dilation, which is considered LATENT or EARLY labor, and if they were not VBAC moms, it would be controversial whether they should have been admitted at that point.  Early labor is often periodic before it picks up into 'true' labor, and many women also experience 'prodromal' labor (so-called false labor, which may come and go for days before active labor kicks in).  Keeping the VBAC moms and then augmenting that early or false labor so aggressively with pitocin may have created an increased opportunity for rupture.  

Once they were admitted, protocols called for an automatic IV line.  If the cervix did not dilate significantly within 2 hours, the patient was supposed to receive morphine sulfate for 'sedation'.  If there were some contractions but little or no change in the cervix after 4 more hours, pitocin was started, with doses increasing every 30 minutes.  It didn't matter if the cervix was unripe and dilation almost nil; pitocin was used.  The authors note defensively that their residents were &