VBAC and Prior Cervical Dilation

Some providers look for any excuse to discourage people from Vaginal Birth After Cesarean (VBAC). They might tell you that you're not a good candidate for VBAC because you are too old, too fat, too short, that you have to have your baby before your due date, that you've gained too much weight, and on and on.

One of the tools that is sometimes used to discourage VBAC is the prior dilation in the previous labor. Some have been told that if they dilated nearly all the way or even all the way to 10 cm, they have little or no chance at a VBAC. Others have been told the opposite, that if they didn't dilate very far previously, their chances of VBAC are low.

But what does the research actually say? 

Prior Dilation and VBAC

A New York study (Hoskins and Gomez 1997) was one of the first studies to look at prior dilation and its association with later VBAC. It found a much greater VBAC rate in those who had a c-section at lower dilation. The VBAC rate at later dilation was only 13%.

However, this is the only study I could find that had more VBACs in the group with less dilation. But because this 1997 study was the first one to really examine the question, its findings have stuck in many doctors' memories, despite contradictory studies, so you sometimes still hear this argument.

A small Nigerian study (Onifade and Omigbodun, 2003) found that prior dilation had no influence on later VBAC. They concluded, "the maximum cervical dilatation reached before primary caesarean section need not be factored into a decision for VBAC."

On the other hand, most studies have found that the greater your dilation in a previous labor, the better your chances at a subsequent VBAC.

One 2001 Canadian study found a higher VBAC rate (75%) among those whose cesareans occurred after dystocia in the second stage of labor/after full dilation. Do note, though, that the group where dystocia occurred in the first stage still had a 66% VBAC rate.

A Korean study (Kwon 2009) also found that those with greater prior dilation had more VBACs.

A Danish study (Abildgaard 2013) had a very low overall VBAC rate but even so found more VBACs in those with greater prior dilation. N=373 women had a Trial of Labor. Those with 4-8 cm dilation before their first cesarean had a 39% VBAC rate, whereas those who were fully or nearly fully dilated at cesarean had a 59% VBAC rate. 

And now, a new study (Lindblad Wollman 2018) also suggests that the chance of VBAC is increased with greater prior dilation. This was a large population-based cohort study in Sweden for 6 years from 2008-2014; such a large study gives its findings extra heft.  N=3,116 women with 1 prior cesarean had a Trial of Labor (TOL). 70% had a VBAC. In those who had a prior cesarean for dystocia:

... increasing cervical dilation in first labor decreased the risk of repeat cesarean in second labor. The adjusted RR of repeat cesarean was 2.48 with dilation ≤5 cm, 1.98 with dilation 6-10 cm, and 1.46 if fully dilated. 

CONCLUSIONS: Almost 70% of all women eligible for trial of labor after cesarean had a vaginal birth, even women with a history of labor dystocia had a good chance of success. A greater cervical dilation in the first delivery ending with a cesarean was not in vain, since the chance of vaginal birth in the subsequent delivery increased with greater dilation.

Overall, the research suggests pretty strongly that the more dilation you had previously, the better your likelihood for a VBAC later. Why might that be? Perhaps the key is how ripe the mother's cervix was before labor (a ripe cervix dilates more easily), and that once you've fully dilated once, you're likely to again.

What it doesn't mean is that someone who didn't dilate very far the first time is a bad candidate for a VBAC. As the Swedish study above points out, "even women with a history of labor dystocia had a good chance of success."

But really, in the end, who cares how many centimeters you dilated last time? The point is that with patience and a supportive provider, most people will have a VBAC, regardless of risk factors. That's all you really need to know.

Providers, Stop Looking for Excuses 

As the top graphic of this post points out, VBAC is woefully underused. About 90% of those with prior cesareans are eligible for a VBAC, yet only about 10% end up having one. Yes, some people choose repeat cesareans, and some people labor for a VBAC but end up with another cesarean. However, the biggest reason for the low number of VBACs is because VBAC has been strongly discouraged by many providers.

Some providers won't support VBAC at all. Others pretend to be supportive but place so many limitations on a trial of labor that almost no one gets a VBAC. Others limit trials of labor to only those with the MOST favorable risk factors.

Providers, stop making excuses. Don't use prior cervical dilation or past arrest disorder or gestational age or Body Mass Index or maternal age or any of a thousand other lame excuses to discourage people from a VBAC.

Arbitrarily limiting VBAC to those with only the most favorable factors makes the repeat cesarean rate far too high, results in far too many complications, and does more harm than good. Our skyrocketing rate of placental abnormalities, cesarean scar pregnancies, and maternal mortality rates reflect that.

Sure, certain factors may make a VBAC slightly more or less likely, but the stark truth is that the majority of those who labor will have a VBAC, even when there are less favorable risk factors.

Stop looking for excuses to not support VBAC. Stop the high-handed paternalism that peremptorily decides birthing choices for others. Stop infantalizing women and taking away their autonomy to make their own medical decisions. People should be counseled about the benefits and risks of each option, but in the end the final choice belongs to the mother.

Unless someone has a legitimate medical contraindication, stop discouraging people from pursuing a VBAC if they want one.

References

Acta Obstet Gynecol Scand. 2018 Dec;97(12):1524-1529. doi: 10.1111/aogs.13447. Epub 2018 Sep 25. Risk of repeat cesarean delivery in women undergoing trial of labor: A population-based cohort study. Lindblad Wollmann C, Ahlberg M, Saltvedt S, Johansson K, Elvander C, Stephansson O. PMID: 30132803

... We investigated the association between indication of first cesarean and cervical dilation during labor preceding the first cesarean and risk of repeat cesarean in women undergoing trial of labor. MATERIAL AND METHODS: A population-based cohort study using electronic medical records of all women delivering in the Stockholm-Gotland region, Sweden, between 2008 and 2014. The population consisted of 3116 women with a first cesarean undergoing a trial of labor with a singleton infant in cephalic presentation at ≥37 weeks of gestation... In women with a cesarean due to dystocia, increasing cervical dilation in first labor decreased the risk of repeat cesarean in second labor. The adjusted RR of repeat cesarean was 2.48 with dilation ≤5 cm, 1.98 with dilation 6-10 cm, and 1.46 if fully dilated. CONCLUSIONS: Almost 70% of all women eligible for trial of labor after cesarean had a vaginal birth, even women with a history of labor dystocia had a good chance of success. A greater cervical dilation in the first delivery ending with a cesarean was not in vain, since the chance of vaginal birth in the subsequent delivery increased with greater dilation.

Acta Obstet Gynecol Scand. 2013 Feb;92(2):193-7. doi: 10.1111/aogs.12023. Epub 2012 Nov 5. Cervical dilation at the time of cesarean section for dystocia -- effect on subsequent trial of labor. Abildgaard H, Ingerslev MD, Nickelsen C, Secher NJ. PMID: 23025257

... DESIGN: Retrospective study. SETTING: University hospital in Copenhagen capital area. POPULATION: All women with a prior cesarean section due to dystocia who had undergone a subsequent pregnancy with a singleton delivery during 2006-2010. METHODS: Medical records were reviewed for prior vaginal birth, cervical dilation reached before cesarean section and induction of labor, gestational age, use of oxytocin, epidural anesthesia and mode of birth was collected. RESULTS: A total of 889 women were included; 373 had had a trial of labor. The success rate for vaginal birth among women with prior cesarean section for dystocia at 4-8 cm dilation was 39%, but 59% for women in whom prior cesarean section had been done at a fully or almost fully dilated cervix (9-10 cm) (p < 0.001). Among the women with a previous vaginal delivery prior to their cesarean section, the success rate for vaginal birth was 76.2%, in contrast to 48.9% in the group without a previous vaginal delivery (p < 0.01). CONCLUSION: Women who had a trial of labor after a prior cesarean section for dystocia done late in labor and women with a vaginal delivery prior to their cesarean section had a greater chance of a successful vaginal birth during a subsequent delivery.

J Matern Fetal Neonatal Med. 2009 Nov;22(11):1057-62. doi: 10.3109/14767050902874089. Cervical dilatation at the time of cesarean section may affect the success of a subsequent vaginal delivery. Kwon JY, Jo YS, Lee GS, Kim SJ, Shin JC, Lee Y. PMID: 19900044

... The medical records of women attempting VBAC between January 2000 and February 2008 were reviewed. All women had only one previous cesarean and underwent spontaneous labor. RESULTS: Among 1148 enrolled women, 956 (83.3%) achieved a successful VBAC. Birth weight, previous indication for cesarean delivery and oxytocin augmentation were significantly associated with VBAC outcome. By multivariate analysis, a cervical dilatation >or=8 cm at previous cesarean was independently predictive of successful VBAC in women with a previous cesarean for non-recurrent indications (p = 0.046), yielding a VBAC success rate of 93.1%, whereas the extent of cervical dilatation at the previous cesarean did not affect the outcome of subsequent delivery in women with a previous cesarean for recurrent indications. CONCLUSIONS: Women with cesarean for non-recurrent indications who achieved a cervical dilatation >or=8 cm may be the best candidates for VBAC, with the greatest likelihood of a successful VBAC. Labor progress at previous cesarean can serve as a valuable indicator for VBAC outcome in women with a previous cesarean for non-recurrent indications, and therefore should be discussed as part of preconception counseling.

Obstet Gynecol. 1997 Apr;89(4):591-3. Correlation between maximum cervical dilatation at cesarean  delivery and subsequent vaginal birth after cesarean delivery. Hoskins IA, Gomez JL. PMID: 9083318

... Relevant records of the index pregnancy (group I) were reviewed for cervical dilatation at cesarean delivery, oxytocin use, indication, neonatal weight, and epidural use. The records of the subsequent pregnancy (group II) were reviewed for successful VBAC rates, neonatal weight, oxytocin, and epidural use. RESULTS: There were 1917 patients in the study. The indications for cesarean in group I were ... arrest disorders (80%)... In those with previous cesarean deliveries for arrest disorders with cervical dilatation at 5 cm or less, the VBAC success rate was 67%. It was 73% for 6-9 cm dilatation and 13% for the fully dilated group (P < .05). CONCLUSIONS: Patients who attempt a VBAC may be counseled that a cesarean delivery at full dilatation is associated with a reduced chance of a subsequent successful VBAC.

AJP Rep. 2017 Jan;7(1):e31-e38. doi: 10.1055/s-0037-1599129. Validation of a Prediction Model for Vaginal Birth after Cesarean Delivery Reveals Unexpected Success in a Diverse American Population. Maykin MM, Mularz AJ, Lee LK, Valderramos SG. PMID: 28255520 Full free text here.

OBJECTIVE: To investigate the validity of a prediction model for success of vaginal birth after cesarean delivery (VBAC) in an ethnically diverse population. METHODS: We performed a retrospective cohort study of women admitted at a single academic institution for a trial of labor after cesarean from May 2007 to January 2015. Individual predicted success rates were calculated using the Maternal-Fetal Medicine Units Network prediction model. Participants were stratified into three probability-of-success groups: low (<35%), moderate (35-65%), and high (>65%). The actual versus predicted success rates were compared. RESULTS: In total, 568 women met inclusion criteria. Successful VBAC occurred in 402 (71%), compared with a predicted success rate of 66% (p = 0.016). Actual VBAC success rates were higher than predicted by the model in the low (57 vs. 29%; p < 0.001) and moderate (61 vs. 52%; p = 0.003) groups. In the high probability group, the observed and predicted VBAC rates were the same (79%). CONCLUSION: When the predicted success rate was above 65%, the model was highly accurate. In contrast, for women with predicted success rates <35%, actual VBAC rates were nearly twofold higher in our population, suggesting that they should not be discouraged by a low prediction score.

Other So-Called "Risk Factors" for Failed VBAC

• https://wellroundedmama.blogspot.com/2018/04/vbac-after-cesarean-for-arrest-of.html 
• https://wellroundedmama.blogspot.com/2018/02/cinderella-vbacs-and-gestational-age.html
• https://wellroundedmama.blogspot.com/2017/08/vbac-prediction-models-actual-results.html
• https://wellroundedmama.blogspot.com/2013/06/cesarean-scar-pregnancy-another.html
• https://www.ncbi.nlm.nih.gov/pubmed/28851168

External Cephalic Version after Prior Cesarean - 2018 study

People whose babies are breech and have a history of a prior cesarean are often told that External Cephalic Version (ECV), manually encouraging the baby to turn head-down, is simply not a choice for them. The fear is that manipulation done during an ECV might make the uterus rupture along the scar from the prior cesarean.

We have discussed ECV after a Prior Cesarean extensively before. The results of all the studies so far suggest that ECV after prior CS is not unduly risky and can avoid many unnecessary repeat cesareans. ECV should be offered to women at term with a breech presentation, regardless of prior cesarean status. Unfortunately, ECV is woefully underutilized. One study from New Zealand estimated that only 26% of eligible patients with breech presentations were referred for ECV.

2018 Study

Recently, a new study (Impey 2018) was published that looks again at the question of ECV after prior cesarean (CS). Its results were both encouraging and disappointing.

In this new U.K. study, researchers looked back retrospectively over a 16 year period and found 100 cases where babies of women with a prior cesarean presented breech at term, were offered, and consented to a ECV.

Basically, the study found about a 50% rate of success in turning the baby head-down. Those who had head-down babies afterwards had a trial of labor after cesarean (TOLAC), and 68% had a VBAC.

The authors did a literature search on ECV after prior CS and found no increased rate of uterine rupture after ECV. That agrees with the literature search we did.

However, the authors chose to dilute this good news by pointing out that while ECV avoided some cesareans, only 30 women out of the 100 original group had a VBAC. In other words, while they found the practice safe, the way they word the abstract made it sound like instituting a practice of ECV after prior cesarean is not worth pursuing because it is only marginally successful.

This flies in the face of previous research. The big question is why their ECV success rate was so low. Only 50% of their ECV tries worked to turn the baby head-down. That reduced their candidates for TOLAC by half, and then only about 2/3 of these women had a VBAC. That's why the final numbers were low.

If you look at comparable studies, Weill 2016 had a 74% ECV success rate, while Burgos 2014 had a 67% ECV success rate. Why were their results so much better? That's what the UK study authors should be asking themselves. Seems like they need training on how to do ECV more successfully.

Summary

The good news from the study is that External Cephalic Version after a prior cesarean is safe. There are potential risks inherent to the procedure, of course, but these risks do not appear to be any greater in women with prior cesarean than in those without a prior cesarean. And of course, the alternative of an automatic repeat cesarean with a breech carries its own potential risks that also must be considered. The choice should be up to the mother.

The bad news from the study is how few women with prior cesareans are being offered ECV and how low the ECV success rate was. It took 16 years in the study to find a data pool of 100 women who had a prior cesarean and a breech presentation at term who were offered an external version and who accepted it. ECV is tremendously underused, especially in those with a prior cesarean. And a ECV success rate of only 50% is pitiful. Better training is obviously needed.

External Cephalic Version at term can avoid many unnecessary cesareans, yet it is woefully underused in many institutions. It is a reasonable choice that needs to be expanded, especially in women with prior cesareans. Furthermore, training to achieve greater ECV success rates in more places needs to occur.



References

Eur J Obstet Gynecol Reprod Biol. 2018 Dec;231:210-213. doi: 10.1016/j.ejogrb.2018.10.036. Epub 2018 Oct 22. External cephalic version after previous cesarean section: A cohort study of 100 consecutive attempts. Impey ORE, Greenwood CEL, Impey LWM. PMID: 30412904

OBJECTIVE: External cephalic version is commonly not performed in women with a previous cesarean section. Fear of uterine rupture and cesarean section in labor are prominent. The risks, however, of these are unclear. This study aims to document the safety and efficacy of external cephalic version in women with a prior cesarean section in a series of 100 consecutive attempts, and to perform a literature of the existing literature. STUDY DESIGN: This is a retrospective cohort study of prospectively collected data of external cephalic version attempts in women at term with a previous cesarean section, and a literature review of previously published series. External cephalic version was performed by one of 3 experienced operators, with salbutamol tocolysis if appropriate, using ultrasound to visualize the fetal heart and place of fetal parts. RESULTS: 100 women with a prior cesarean section underwent external cephalic version over a 16-year period in one institution. 68% had no previous vaginal delivery. The external cephalic version success rate was 50%, and 30 (63.8%) of these subsequently delivered vaginally. There were no cases of uterine rupture or other complications. A literature review of series containing a total of 549 cases revealed no cases of uterine rupture or perinatal death. CONCLUSIONS: External cephalic version in women with a prior cesarean section is safe but enables a vaginal birth in only about a third of women.

Aust N Z J Obstet Gynaecol. 2016 Sep 14. doi: 10.1111/ajo.12527. [Epub ahead of print] The efficacy and safety of external cephalic version after a previous caesarean delivery. Weill Y, Pollack RN. PMID: 27624629

BACKGROUND: External cephalic version (ECV) in the presence of a uterine scar is still considered a relative contraindication despite encouraging studies of the efficacy and safety of this procedure. We present our experience with this patient population, which is the largest cohort published to date. AIMS: To evaluate the efficacy and safety of ECV in the setting of a prior caesarean delivery. MATERIALS AND METHODS: A total of 158 patients with a fetus presenting as breech, who had an unscarred uterus, had an ECV performed. Similarly, 158 patients with a fetus presenting as breech, and who had undergone a prior caesarean delivery also underwent an ECV. Outcomes were compared. RESULTS: ECV was successfully performed in 136/158 (86.1%) patients in the control group. Of these patients, 6/136 (4.4%) delivered by caesarean delivery. In the study group, 117/158 (74.1%) patients had a successful ECV performed. Of these patients, 12/117 (10.3%) delivered by caesarean delivery. There were no significant complications in either of the groups. CONCLUSIONS: ECV may be successfully performed in patients with a previous caesarean delivery. It is associated with a high success rate, and is not associated with an increase in complications.

BJOG. 2014 Jan;121(2):230-5; discussion 235. doi: 10.1111/1471-0528.12487. Epub 2013 Nov 19. Is external cephalic version at term contraindicated in previous caesarean section? A prospective comparative cohort study. Burgos J, Cobos P, Rodríguez L, Osuna C, Centeno MM, Martínez-Astorquiza T, Fernández-Llebrez L. PMID: 24245964

OBJECTIVE: To determine if external cephalic version (ECV) can be performed with safety and efficacy in women with previous caesarean section. DESIGN: Prospective comparative cohort study. SETTING: Cruces University Hospital (Spain). POPULATION: Single pregnancy with breech presentation at term. METHODS: We compared 70 ECV performed in women with previous caesarean section with 387 ECV performed in multiparous women (March 2002 to June 2012). MAIN OUTCOME MEASURES: Success rate, complications of the ECV and caesarean section rate. RESULTS: The success rate of ECV in women after previous caesarean section was 67.1% versus 66.1% in multiparous women (P = 0.87). The logistic regression analysis confirmed this result (odds ratio 0.93, 95% CI 0.52-1.68; P = 0.82) adjusted by the variables associated with success of ECV. There were no complications in the previous caesarean section cohort. The vaginal delivery rate in the previous caesarean section cohort was 52.8% versus 74.9% in the multiparous cohort (P < 0.01). There were no cases of uterine rupture. CONCLUSION: Based on our data, we conclude that complications are uncommon with ECV in women with previous caesarean section, with a success rate comparable to that of multiparous women. Uterine scar should not be considered a contraindication and ECV should be offered to women with previous caesarean section with breech presentation at term.

Click here for older references on ECV after CS.

Women Are Dying From This: Taking Cesareans Seriously

When women have cesareans, they are rarely warned that a possible complication can be placental problems in future pregnancies.

Many women (and especially higher weight women) are pressured into cesareans in their first pregnancy. Many of these same women are counseled away from Vaginal Birth After Cesarean (VBAC) and into repeat cesareans in subsequent pregnancies.

Few of these women have been told that cesareans raise the risk for Placenta Accreta, a very serious complication, and that every cesarean increases the risk for it. I know *I* wasn't told this. This is a tremendous disservice to parents and to the importance of informed consent.

About Accreta

In Placenta Accreta, the fertilized egg implants near or on scar tissue in the uterus. This scar tissue is usually from a prior cesarean, but can also be from a D&C procedure, fibroid removals, a perforation from an IUD, or any uterine surgery or instrumentation. The placenta then grows into the uterine wall in this scar tissue. After the baby is born (often prematurely), the placenta can't separate properly and bleeding can become prolific. If the bleeding is not resolved, the mother can die.

There are degrees of Placenta Accreta. When the placenta grows into the uterine wall, that's Placenta Accreta. 

When the placenta invades the muscles of the uterus, that's known as Placenta Increta.

When the placenta grows through the uterine wall and into nearby organs like the bladder, that's called Placenta Percreta. All are extremely serious conditions, but percreta is the most serious of all.

The accreta rate has risen over the years as the cesarean rate has increased. Doctors are seeing more and more cases these days of what used to be a very rare complication. Some data indicate that the accreta rate has risen from about 1 in 4000 in the 1970s to about 1 in 533 now.

You can read more about this in my blog series on Placenta Accreta.

• Part One - What Is Placenta Accreta?
• Part Two - Life-Threatening Complication of Prior Cesarean 
• Part Three - Risks to Mother and Baby
• Part Four - Diagnosis, Treatment, and a Cautionary Story

The absolute numerical risk of accreta occurring in any one person is low, even with prior cesareans. Most women who have had cesareans will not experience an accreta. However, it is such a life-threatening condition that even a relatively small incidence carries a tremendous burden of complications, cost, and potential loss of life.

The more cesareans you have had, the greater the risk for accreta. In one very large study (Silver 2006), accreta was present in:

• 0.24% of women undergoing their first cesarean (previously unscarred)
• 0.31% of women undergoing their second cesarean (one prior cesarean)
• 0.57% of women undergoing their third cesarean (two prior cesareans)
• 2.13% of women undergoing their fourth cesarean (three prior cesareans)
• 2.33% of women undergoing their fifth cesarean (four prior cesareans)
• 6.74% of women undergoing their sixth or more cesarean (five or more prior cesareans)

This is why it is important to avoid automatic repeat cesareans and to keep VBAC a viable choice. Multiple repeat cesareans are the single most preventable factor for accretas. 

Accreta does sometimes occur after only one cesarean, like the woman in the video below, and that's why it's important to prevent a first cesarean whenever possible as well.

One Mother's Accreta Story

This mother had only had ONE prior cesarean, but still developed accreta with baby #2. Her first cesarean was a planned cesarean, urged by her OB. She was never warned that her cesarean meant accreta was a potential risk for the future.

THIS is why the high cesarean rate matters. On a case-by-case basis, a cesarean can be a good thing. But the public health implication of a high cesarean rate is that more women will develop life-threatening complications like placenta accreta, more babies will be born prematurely, and more women will die or experience permanent damage. Sometimes even after only one cesarean.

If we want to decrease maternal mortality rates and prevent complications from accreta, we MUST decrease cesarean rates. As the mother in the video below states:

A cesarean can be a life-saving intervention. The goal is not to eliminate cesareans. The goal is to make decisions regarding cesareans appropriately, and to recognize that even an uncomplicated cesarean and recovery can still put the mother at significant future risk....

She continues:

"There are too many cesareans now, 1 in 3 births, and researchers estimate that as many as 50% of those are unnecessary. 

And since a prior cesarean is a significant risk factor for developing a future accreta, that means that there are women developing accreta when it could have been prevented. So the easiest way to reduce the amount of accretas is to reduce cesarean levels... 

Women are dying from this, and mothers are dying from this. We need to take the risks of a cesarean seriously."

VBAC after VBAC: Decreased Risk

A large new study on VBAC after prior VBAC has just come out, and it affirms what we've seen before, that risk for subsequent labors goes down and success rates go up after a previous VBAC.

Krispin 2018 Study

This is a large retrospective cohort study from Israel. It looked back at all women who attempted a VBAC at a major hospital over a period of 7 years (2007-2014).

The study group (n=1,211) contained the women with at least one prior VBAC. The control group (n=2,045) was comprised of women pursuing their first VBAC.

As we've seen before, a prior VBAC increases the chances of another VBAC. So it was in this study, too. Those with a prior VBAC had a 96% subsequent VBAC rate. (I think that's the highest VBAC rate of any study I've ever seen!)

However, even the women pursuing their first VBAC had a high rate, nearly 85%. This suggests that the Israelis are doing something right when it comes to attending VBACs, because their VBAC rates are much better than those of many U.S. hospitals.

Induction of labor was associated with reduced VBAC rates, cutting the VBAC odds by half, but induction rates were fairly low compared to some practices. This allowed the success rate to stay high overall.

The study confirmed that a prior VBAC greatly lessens the risk for uterine rupture (UR). The uterine rupture rate in those with a prior VBAC was 0.7%, whereas it was 1.6% in the women with their first Trial of Labor (TOL).

The take-home from this study is that when other variables were controlled for, having a prior VBAC cut the odds for uterine rupture in half in subsequent labors. 

Even so, both groups of UR numbers seem a little high, probably because the hospital used prostaglandins (PGE2) to induce their VBACs. Prostaglandins (and especially prostaglandins plus pitocin) have been shown to increase the risk for uterine rupture. Unfortunately, the study did not share the rupture rate in the induced groups vs. the rupture rate in the spontaneous labor groups. That would have been illuminating.

It's also important to point out that the risk for rupture wasn't zero. Even after a VBAC, uterine rupture is still a potential risk and has been known to occur. Neither is prior VBAC a guarantee of subsequent VBAC outcomes; there's always a chance of another cesarean because unpredictable things happen in labor.

But it's good to confirm again that the risk for uterine rupture is substantially lower once you've had a VBAC, and that your chances of having another VBAC are very good indeed.

Other VBAC after VBAC Studies

This is not the first study on successive multiple VBACs. Prior research also shows improved outcomes with previous VBAC. For example, Shimonivitz (2000) found the risk for uterine rupture "decreased dramatically" once a woman has had a VBAC.

Some women have reported being told that risk for uterine rupture goes back up again after a certain number of VBACs and that therefore only a few VBACs can be allowed before a woman is required to have repeat cesareans again. This claim is not based in research at all and flies in the face of common sense.

The most definitive study on this claim is Mercer (2008), who studied multiple successive VBACs in 19 hospitals in the MFMU network. They found that UR rates dropped after the first VBAC and remained low thereafter:

Among 13,532 women meeting eligibility criteria, VBAC success increased with increasing number of prior VBACs: 63.3%, 87.6%, 90.9%, 90.6%, and 91.6% for those with 0, 1, 2, 3, and 4 or more prior VBACs, respectively (P<.001). The rate of uterine rupture decreased after the first successful VBAC and did not increase thereafter: 0.87%, 0.45%, 0.38%, 0.54%, 0.52% (P=.03). The risk of uterine dehiscence and other peripartum complications also declined statistically after the first successful VBAC. No increase in neonatal morbidities was seen with increasing VBAC number thereafter.

The other consideration is that if a woman is not "allowed" to VBAC, she ends up with multiple repeat cesareans, which carry significant risks of complications such as placenta previa, placenta accreta, bladder and bowel injuries, hemorrhage, and hysterectomy (Silver 2006). The risk is dose-dependent, meaning that the risk increases with every successive cesarean a woman has. If a woman is planning a large family, the evidence clearly shows that repeated VBACs are far safer than repeated cesareans.

As Mercer et al. conclude:

Women with prior successful VBAC attempts are at low risk for maternal and neonatal complications during subsequent VBAC attempts. An increasing number of prior VBACs is associated with a greater probability of VBAC success, as well as a lower risk of uterine rupture and perinatal complications in the current pregnancy. There is no reason to place a limit on the number of VBACs a woman can have.

Summary

Once you've had a VBAC, you have an even better chance than before at another VBAC. It's not a guarantee, of course, but most studies show the VBAC after VBAC rate to be above 90%.

The uterine rupture rate after prior VBAC seems to fall between 0.4% and 0.7%. However, it will vary depending on how much induction is used, what induction methods are used, how aggressive providers are with augmentation, and any other other risk factors present. Whatever the exact number is, studies show that the uterine rupture rate decreases strongly after a prior VBAC but there should always be an awareness of the possibility.

The bottom line is that the risk for poor outcomes goes down with successive VBACs, while the risk for poor outcomes goes up with multiple repeat cesareans. In most cases, VBAC after VBAC offers far more advantages and should not be restricted. 


References

J Matern Fetal Neonatal Med. 2018 Apr;31(8):1066-1072. doi: 10.1080/14767058.2017.1306513. Epub 2017 Mar 27. Association between prior vaginal birth after cesarean and subsequent labor outcome. Krispin E, Hiersch L, Wilk Goldsher Y, Wiznitzer A, Yogev Y, Ashwal E. PMID: 28285573

OBJECTIVE: To estimate the effect of prior successful vaginal birth after cesarean (VBAC) on the rate of uterine rupture and delivery outcome in women undergoing labor after cesarean. METHODS: A retrospective cohort study of all women attempting labor after cesarean delivery in a university-affiliated tertiary-hospital (2007-2014) was conducted. Study group included women attempting vaginal delivery with a history of cesarean delivery and at least one prior VBAC. Control group included women attempting first vaginal delivery following cesarean delivery. Primary outcome was defined as the rate of uterine rupture. Secondary outcomes were delivery and maternal outcomes. RESULTS: Of 62,463 deliveries during the study period, 3256 met inclusion criteria. One thousand two hundred and eleven women had VBAC prior to the index labor and 2045 underwent their first labor after cesarean. Women in the study group had a significantly lower rate of uterine rupture 9 (0.7%) in respect to control 33 (1.6%), p = .036, and had a higher rate of successful vaginal birth (96 vs. 84.9%, p < .001). In multivariate analysis, previous VBAC was associated with decreased risk of uterine rupture (OR = 0.46, 95% CI 0.21-0.97, p = .04). CONCLUSIONS: In women attempting labor after cesarean, prior VBAC appears to be associated with lower rate of uterine rupture and higher rate of successful vaginal birth.

Similar Studies on VBAC After VBAC

Mercer BM, Gilbert S, Landon MB. et al. Labor Outcomes With Increasing Number of Prior Vaginal Births After Cesarean Delivery. Obstet Gynecol. 2008 Feb;111(2):285-291. PMID: 18238964 You can read the entire study here.

OBJECTIVE: To estimate the success rates and risks of an attempted vaginal birth after cesarean delivery (VBAC) according to the number of prior successful VBACs. METHODS: From a prospective multicenter registry collected at 19 clinical centers from 1999 to 2002, we selected women with one or more prior low transverse cesarean deliveries who attempted a VBAC in the current pregnancy. Outcomes were compared according to the number of prior VBAC attempts subsequent to the last cesarean delivery. RESULTS: Among 13,532 women meeting eligibility criteria, VBAC success increased with increasing number of prior VBACs: 63.3%, 87.6%, 90.9%, 90.6%, and 91.6% for those with 0, 1, 2, 3, and 4 or more prior VBACs, respectively (P<.001). The rate of uterine rupture decreased after the first successful VBAC and did not increase thereafter: 0.87%, 0.45%, 0.38%, 0.54%, 0.52% (P=.03). The risk of uterine dehiscence and other peripartum complications also declined statistically after the first successful VBAC. No increase in neonatal morbidities was seen with increasing VBAC number thereafter. CONCLUSION: Women with prior successful VBAC attempts are at low risk for maternal and neonatal complications during subsequent VBAC attempts. An increasing number of prior VBACs is associated with a greater probability of VBAC success, as well as a lower risk of uterine rupture and perinatal complications in the current pregnancy.

Isr Med Assoc J 2000 Jul;2(7):526-8. Successful first vaginal birth after cesarean section: a predictor of reduced risk for uterine rupture in subsequent deliveries. Shimonovitz S, Botosneano A, Hochner-Celnikier D. PMID: 10979328

...Although a vaginal birth after a cesarean is considered safe in modern obstetrics, it is not known whether repeated VBACs increase the risk of rupture, or whether the first VBAC proves the strength and durability of the scar, predicting further successful and less risky vaginal deliveries. OBJECTIVES: To evaluate the effect of repeated vaginal deliveries on the risk of uterine rupture in women who have previously delivered by cesarean section. METHODS: In this retrospective study, 26 VBAC deliveries complicated by uterine rupture were matched for age, parity, and gravidity with 66 controls who achieved VBAC without rupture... We found that the risk of rupture decreases dramatically in subsequent VBACs. Of the 40 cases of uterine rupture recorded during the 18 year study period, 26 occurred during VBAC deliveries. Of these, 21 were complicated first VBACs. We also found that the use of prostaglandin-estradiol, instrumental deliveries, and oxytocin had been used significantly more often during deliveries complicated with rupture than in VBAC controls. CONCLUSIONS: Once a woman has achieved VBAC the risk of rupture falls dramatically. The use of oxytocin, PGE2 and instrumental deliveries are additional risk factors for rupture, therefore caution should be exerted regarding their application in the presence of a uterine scar, particularly in the first vaginal birth after cesarean.

Risks of Multiple Repeat Cesareans

Obstet Gynecol. 2006 Jun;107(6):1226-32.National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Maternal morbidity associated with multiple repeat cesarean deliveries. Silver RM,  et al.  PMID: 16738145

...METHODS: Prospective observational cohort of 30,132 women who had cesarean delivery without labor in 19 academic centers over 4 years (1999-2002). RESULTS: There were 6,201 first (primary), 15,808 second, 6,324 third, 1,452 fourth, 258 fifth, and 89 sixth or more cesarean deliveries. The risks of placenta accreta, cystotomy, bowel injury, ureteral injury, and ileus, the need for postoperative ventilation, intensive care unit admission, hysterectomy, and blood transfusion requiring 4 or more units, and the duration of operative time and hospital stay significantly increased with increasing number of cesarean deliveries. Placenta accreta was present in 15 (0.24%), 49 (0.31%), 36 (0.57%), 31 (2.13%), 6 (2.33%), and 6 (6.74%) women undergoing their first, second, third, fourth, fifth, and sixth or more cesarean deliveries, respectively. Hysterectomy was required in 40 (0.65%) first, 67 (0.42%) second, 57 (0.90%) third, 35 (2.41%) fourth, 9 (3.49%) fifth, and 8 (8.99%) sixth or more cesarean deliveries. In the 723 women with previa, the risk for placenta accreta was 3%, 11%, 40%, 61%, and 67% for first, second, third, fourth, and fifth or more repeat cesarean deliveries, respectively. CONCLUSION: Because serious maternal morbidity increases progressively with increasing number of cesarean deliveries, the number of intended pregnancies should be considered during counseling regarding elective repeat cesarean operation versus a trial of labor and when debating the merits of elective primary cesarean delivery.

VBAC after Cesarean for Arrest of Descent or Cephalo-Pelvic Disproportion

Your pelvis is NOT defective

A cesarean for "Arrest of Descent" means a cesarean done after a woman has dilated fully and pushed for a while without the baby descending. The amount of pushing time required for the diagnosis varies from source to source but is usually at least 1-3 hours.

When a woman has a cesarean for Arrest of Descent, she is often told something is wrong with her pelvis. She might be told she has:

• A "flat" sacrum 
• A "prominent" sacrum
• A pubic arch that is "too narrow"
• Ischial spines that are "too prominent" 
• A pelvis that is "too small"
• "Too much soft tissue" (fat) lining the vagina/pelvis
• A pelvis that is the "wrong shape" 
• A baby that was "too big" for her pelvis 
• "Cephalo-Pelvic Disproportion" (baby too big and pelvis too small, causing baby to not fit)

Often women who have been told these things are strongly discouraged from trying for a Vaginal Birth After Cesarean (VBAC). There are documented cases where women have been told their pelvis is too flat or too small to have a VBAC, that they have "soft tissue dystocia" (a.k.a. "fat vagina"), that their pelvis is the wrong shape, or that since they couldn't push out a baby before, chances are they never will be able to because CPD is a recurring condition:

Yesterday, at my appt, while speaking with one of the midwives - she asked if I wanted her honest opinion & that if I was unable to push out a 7 and 1/2 pound baby and 2nd babies are normally larger then she didn't think it would be successful. 

The bottom line is that providers that are not truly VBAC-supportive often make women believe that something is wrong with their bodies and that they have little chance of having a vaginal birth, implying it's better just to schedule a repeat cesarean. Then the care providers conveniently have fewer VBAC labors to attend.

However, many women who have been told they have an abnormal pelvis or soft tissue dystocia or who have had a cesarean for Arrest of Descent or CPD have gone on to have VBACs anyhow.

And a new study just out confirms that many women with a prior cesarean for Arrest of Descent do indeed go on to have a VBAC and should not be discouraged from trying.

New Study on VBAC after Arrest of Descent

A recent American study (Fox 2018) shows that VBAC after prior Arrest of Descent is often successful.

In the study, one hundred women who had one prior cesarean for Arrest of Descent had a "Trial Of Labor After Cesarean" (TOLAC or TOL). A whopping 84% ended up having a VBAC. This is an excellent rate and better on average than many VBAC studies.

The authors concluded (my emphasis):

This suggests that arrest of descent is mostly dependent on factors unique to each pregnancy and not due to an inadequate pelvis or recurring conditions. Women with a prior CD [Cesarean Delivery] for arrest of descent should not be discouraged from attempting TOLAC in a subsequent pregnancy due to concerns about the likelihood of success.

The fact that the authors state this so strongly in an obstetrics journal is a big deal because it goes against what is commonly taught to many OBs, so let's reemphasize those points:

• Arrest of Descent is NOT usually due to an inadequate pelvis
• "CPD" is not necessarily a recurring condition
• Women with this history should not be discouraged from trying for a VBAC

Many women can and DO have VBACs after diagnoses of CPD and Arrest of Descent. Yet strong discouragement away from VBAC is exactly what happens to many of these women, even today. 

Other Similar Studies

Was this study just a fluke? What do other studies on Arrest of Descent say?

There are only a couple of studies that specifically use the term "VBAC after Arrest of Descent" so you have widen the search a bit. Other search terms to consider include "CPD + cesarean," "cesareans after full dilation," or "cesareans done during second stage of labor" (pushing), or "prolonged second stage," or similar terms. Carefully vetted, these are essentially Arrest of Descent cesareans too.

If you just look at studies that examine VBAC after a cesarean for CPD, research reviews show that about two-thirds of women will have a VBAC. This rate is lower than for those whose first cesarean was for breech or fetal distress, but is still a very good rate. If all those women had been discouraged from VBAC or pressured into repeat cesareans, two-thirds of them would have had unnecessary cesareans!

There is very little data on women who have had more than one cesarean for CPD. However, one 1989 study did contain some data on women like this. If you crunch the data in the full text of the study, women with 2 prior cesareans for CPD had a 56% VBAC rate. So although we don't have a lot of data on this, what we do have suggests that even among women with more than one cesarean for CPD, more than half will have a VBAC.

The doctors who like to discourage VBAC cite a discouraging 1997 study that found a low VBAC rate (13%) in women who had reached full dilation and pushed in their previous labor. However, the rest of the research is much more encouraging.

In one Californian study from 2015, 54% of women with no prior vaginal birth and a prior cesarean during pushing stage went on to have a VBAC. In other words, they were just as likely to have a VBAC as not.

Similarly, a Danish study found a 59% VBAC rate in women whose cesareans occurred at 9-10 cm of dilation (9 cm often represents a fully dilated woman with a cervical lip, likely due to fetal malposition). Again, more than half had a VBAC and avoided the risks of additional surgery.

But some studies have results even better than that. In a New York study, 74.5% of women with prior pushing-stage cesareans went on to have a VBAC, some of them with forceps help, which suggests that fetal malpositions were an issue for quite a few.

Echoing those numbers is a Canadian study that found a 75% VBAC rate in those with a prior second stage dystocia cesarean. A very small, older Irish study found a 73% VBAC rate in those with a prior cesarean in the second stage.

Similarly, an older Dutch study found an 80% VBAC rate in those with a prior Arrest of Descent cesarean. This echoes our current Fox 2018 study that found an 84% VBAC rate after prior Arrest of Descent.

In summary, the majority of the research clearly supports the idea that women with a prior cesarean that occurred after full dilation and pushing can be offered a "trial of labor after cesarean" and will have a quite reasonable chance for a VBAC.

In the end, the decision whether to go for a VBAC is the mother's, but she should be reassured that she is just as likely to have a VBAC as not, and in many practices, especially with proactive care regarding fetal position, her chances are even better.

The Importance of Fetal Position

So what causes Arrest of Descent? Why does it happen in some births but not others in the same mother? The answer is usually fetal position.

In Arrest of Descent/CPD cesareans, the problem is usually the BABY'S POSITION, not the mother's pelvis.

If the baby is not well-positioned, labor tends to be slow and extra painful. It often slows or stalls between 4-7 cm of dilation. Often the mother eventually dilates fully but there is little or no progress during pushing. Fetal distress may occur.

Some providers become impatient and intervene with procedures (like breaking the waters) which may do more harm than good. Frequently, they are too quick to move to surgery when more patience might see the position resolve or the baby be born just fine in the "less-optimal" position. Recent research suggests that more than three-fourths of women with prolonged pushing stages (more than 3 hours) will deliver vaginally if just given a little more time.

What kind of fetal positions can cause problems? Read here for illustrations and specifics of the different fetal positions. The Spinning Babies website also has many helpful articles and illustrations on fetal position and how to help create maximum room in the pelvis. In the meantime, below is a brief introduction of the most common fetal malpositions.

Keep in mind that Presentation refers to which part of the baby is presenting first, and Position refers to how the baby is oriented in the mother's body in a head-down position. Also keep in mind that when describing fetal position, obstetric texts reference the back of the baby's head (the occiput) and which way the occiput is oriented in relationship to the mother. Most laypeople find it easier to understand by thinking of which way the baby is looking, so I use both in my descriptions.

Both the Spinning Babies website and The Labor Progress Handbook by Penny Simkin et al. have many ideas for various ways to help malpositioned babies resolve their position, and for creating more space in the pelvis. We will discuss this further in future posts.

Occiput Anterior (Easiest for Birth)

Occiput Anterior or OA

The easiest fetal position for labor and birth is usually Occiput Anterior. This is abbreviated OA and means the baby is head-down with the back of the baby's head against the mother's front; in other words, the baby is looking towards the mother's back. This position is considered the norm and the vast majority of babies will be born in this position.

Direct OA is when the baby is looking directly back at the mother's sacrum. LOA is when the baby is mostly facing the mother's back but his back is a bit towards the left side; ROA is the same but a bit towards the right side.

Ideally, the baby's chin is tipped towards its chest so the smallest possible diameter of its head presents. If the baby's head is not well-flexed, the presenting diameter is a bit larger. If the baby's head is tipped to one side or the other, it can be even larger. More on that below.

Occiput Posterior 

Illustration by Gail Tully, Spinning Babies

One of the most common fetal positions that can cause problems during labor is the Occiput Posterior position. This is abbreviated OP; the back of baby's head is against your back and baby is looking at your tummy. If the baby is directly facing your back, that's direct OP; if it's a little to the right or left, then that's ROP or LOP.

Although many babies enter labor in less-ideal positions like OP, only about 5% stay posterior all through labor and deliver that way. Babies that come out in the OP position are sometimes called "Stargazers" or "Sunny Side Up."

By itself, an OP position does not have to mean a cesarean, since most OP babies turn during labor and become OA before birth. The labor may be a little longer and more painful but it often proceeds just fine with a little patience. However, babies that are persistently posterior all the way through labor and birth have a high rate of problems.

Research clearly shows that persistent posterior babies have higher rates of cesareans for CPD or Arrest of Descent. This is because the presenting head diameter of a baby in OP position is larger than the baby in an OA position. In addition, the back of the baby's head is against the mother's back and that makes for a more painful labor, with lots of back labor and a slower dilation. This in turn often means lots of interventions from care providers that may make the situation worse, like breaking the waters, which takes away the cushion for baby to turn more easily and may lead to fetal distress.

However, OP babies do not always end with cesareans. With time and patience, an OP baby with a flexed head (chin to chest) can often be born vaginally. Alternatively, a vaginal birth may be possible if the care provider is patient and allows extra time for the baby's head to mold enough to descend into the pelvis. When it hits the pelvic floor, it often then rotates from OP to OA on the perineum and may be born quickly. Often an OP baby can be helped to rotate to OA through manual rotation, an instrumental delivery, or maternal postural changes like the all-fours position.

But because of the impatience of many providers, the fetal distress that can occur, and the extra-painful, longer labors associated with OP babies, many persistent OP babies end up being born by cesarean.

Deflexed Heads

If a baby's head is deflexed (not chin to chest), this can cause problems as well. A deflexed head makes the baby's presenting head diameter larger. This means the baby may not fit through very well, or the baby needs extra time for its head to mold enough to get through. OA babies with mildly deflexed heads experience longer labors, but with a little patience, are usually able to be born vaginally.

However, significant problems can occur if deflexion is extreme. Extreme examples of deflexed heads include a brow (forehead first) or face (face-first) presentation. Although vaginal births of brow and face presentations have been documented, most often they end in cesarean these days unless the baby's position can be resolved. Fortunately, brow and face presentations are quite rare.

Deflexed babies in an OP position are fairly common and result in many long, difficult labors. OP babies already start out with a larger presenting head diameter; when they also have deflexed heads (known as a "military" position), this makes the head diameter even larger. Big OP babies often have deflexed heads, making their head diameters even larger. These babies often have extremely long and hard labors, and many end in cesareans. Turn the baby around and/or tip its chin towards its chest so that the head is flexed and the baby would likely fit much better; many cesareans could be avoided.

Occiput Transverse/Transverse Arrest

Occiput Transverse, which can result
in Transverse Arrest

When a baby's head is directly sideways, facing the hip, this is called Occiput Transverse or OT. Often OT positions are able to resolve to OA, but sometimes they do not and result in a vacuum extraction, forceps delivery, or cesarean.

OT often occurs when the baby was posterior earlier in labor, tries to rotate to anterior, and gets stuck in the process of turning. Sometimes it is iatrogenic (caused by the provider). If labor is slow, the care provider may break the mother's waters in an effort to speed up labor. This removes the buoyant cushion that can make it easier for the baby to finish its turn and the baby may end up "stuck" in this position. This is called "Transverse Arrest." A fair amount of cesareans are caused by transverse arrest.

Compound Presentation

A nuchal hand presenting alongside the head

Babies who have their hands up by their faces (a "nuchal hand" or sometimes a nuchal elbow/arm) can present another challenge.

The baby is basically OA and in a great position for birth, but the hand or arm beside the head causes larger-than-average presenting parts that must fit through at the same time. If the care provider can get the baby to pull back its arm/hand near birth, the baby is likely to then be born quickly. If the arm/hand remains by the baby's head, pushing is likely to be slow, painful, and difficult. Usually babies with nuchal hands can be born vaginally, but there may be quite a bit of tearing and damage to the mother. If the provider is not patient during a slow pushing stage with a nuchal hand/arm, it may result in a cesarean.

Asynclitic Heads

Asynclitic baby in OA position

Similarly, babies who have their heads tipped to the side instead of straight ("asynclitic") also have difficulty fitting. Instead of the top of the head presenting first, their parietal bone (bony side of head) presents first. The tipped head causes a larger than average head diameter that doesn't fit as easily.

Many asynclitic babies will correct the tilt of their heads if the mother's waters are kept intact and she is able to be mobile in labor. Asymmetric birth positions may help correct the tilt. Once the tilt is corrected, the baby is often born fairly quickly.

If the baby is not able to correct the tilt of its head on its own, then the care provider may be able to help through the use of a vacuum extractor or forceps. Sometimes the tilt of the head goes undiscovered or is not able to be resolved during labor; these babies often are born by cesarean.

Summary

Unfortunately, many women with a prior cesarean for CPD or Arrest of Descent are discouraged from even trying to have a VBAC. They may be told they have little chance at a VBAC and they should just schedule a planned repeat cesarean rather than risk another cesarean during labor. One woman was told:

You've already proven you can't get a baby out of your pelvis.

Obviously, that OB believed that the pelvis itself was the issue, not the baby's position, but the recent Arrest of Descent study suggests it is likely not true.

This kind of misleading "guidance" from care providers is not evidence-based. Most women with a prior CPD or Arrest of Descent cesarean who go through with labor actually have a reasonable chance at a VBAC, as this woman found:

The OB that did my c-section told me that my pelvis was small and also tilted and that because of that, a vaginal birth wouldn't be possible. Well, I...went for a VBAC anyway and it's a good thing I did because I had a wonderful amazing and natural VBAC with my next baby. And she came out in about 4 pushes. It was so easy! I had my second VBAC with my son a year ago and it went perfectly as well!

Here is a link to the story of another case where a woman who had a cesarean was told that her pelvis was too small to birth a baby and to forget about a VBAC. She went on to birth a 9 lb. baby ─ with a nuchal hand ─ as a VBAC. The Birth Without Fear blog has an awesome picture of it in their birth stories section.

That's not to say that CPD is never real. Sometimes it is. Although most cases of "CPD" are actually situational (caused by a malposition), sometimes there are rare cases of true CPD. These are usually a result of significant malnourishment in childhood, severe scoliosis, a history of rickets, or a history of a bad fall or accident where the pelvis was damaged. And sometimes, women don't have any of that in their background, really do try everything, and still end up with a cesarean because the baby just didn't fit. It does happen and it's important to acknowledge that.

But far too often, women who have had a cesarean after not being able to push out a baby are told that their pelvises are too small or defective, and they'll never be able to push out a baby. This is not true. Many women with this history can have a vaginal birth, if given an adequate chance to do so. Anecdotally, many women who have been told this benefit from having a good chiropractor evaluate their back and pelvis to help maximize the space in it and get it well-aligned. See my story below.

Women with a history of cesareans for Arrest of Descent or CPD should be offered the chance at a VBAC if they want it. Chances are good they will have one. There are never any guarantees, but research clearly shows that trying for a VBAC is a very reasonable choice in this group and should not be discouraged.

My Story

Again, many women have had cesareans for arrest of descent and yet gone on to have a VBAC. Conventional wisdom is that you need a smaller baby to get a VBAC, but some women do have VBACs with a baby even bigger than their cesarean baby. Again, fetal position is key.

This includes me. I had my first cesarean after a difficult induced labor. I dilated to 10 cm and pushed for two hours in stirrups, but ended up with a very traumatic cesarean. With my second baby, I had a relatively easy spontaneous labor where I did all the "right" things including position changes but still had FIVE HARD HOURS of pushing with little descent of my deflexed OP baby. I ended up with a second cesarean for CPD.

Both of my babies were big. I was told I had a "marginal" pelvis by my first care provider, and unless I had a smaller baby I would probably not have a vaginal birth. After my second birth, a nurse-midwife told me I probably had a pelvic shape predisposed to posterior babies and my babies would likely always be posterior. After two CPD cesareans at full dilation and after hours of pushing, I was told I was extremely unlikely to have a VBAC. The "VBAC Calculator" gave around a 20% chance of having a VBAC if I tried again.

All these declarations were wrong in the end but it was difficult to have faith. In my third pregnancy, I wavered between choosing to labor again or just going straight to a repeat cesarean. The baby was consistently posterior again all through pregnancy and I had no desire to go through a long hard labor only to end up with another cesarean ─ but neither did I want to go through another surgical recovery. I was also worried about the increase the risk of placental issues from another cesarean if I decided to have another baby in the future.

Near the end of my third pregnancy, I found a chiropractor who did a lot of work on my pelvis, including the Webster Technique and releasing the round ligaments that attach to the uterus. She felt my history of car accidents was highly relevant to the malpositions going on. According to her, the significant back and pubic pain I was having indicated "in utero constraint" that was making it hard for my babies to be in the easiest position for labor. The chiropractic adjustments eased a lot of my discomfort and the baby moved pretty quickly into a more optimal OA position for the first time in three pregnancies!

I went on to have a VBAC after 2 cesareans (VBA2C), something many providers would have told me would be extremely unlikely with my history and risk factors (short, old, "morbidly obese," big babies, two prior CPD cesareans, no prior vaginal births). Instead of pushing for 2 hours or for 5 hours as I did with my first two children, I pushed for 12 minutes with that baby. The doctor didn't even make it to the birth.

And it wasn't just a lucky fluke. Several years later, I had another VBA2C, this time with a baby that was a pound larger than either of my cesarean babies. I only pushed for 24 minutes with that baby.

Afterwards I asked my midwife to evaluate my pelvis and tell me honestly if it was truly marginal or not. She examined me and said it absolutely was not. Either the prior evaluation was wrong or chiropractic care really did create more space in my pelvis ─ or maybe a little of both. I do feel that the chiropractic care was integral to my VBACs, given that I never had an anterior baby until I had chiropractic care.

Remember, each labor and birth is unique and previous problems do not necessarily happen again.

Even a history of more than one Arrest of Descent or CPD cesarean does not mean it will continue to happen, especially if the mother is very proactive about fetal position. I had a history of TWO cesareans for Arrest of Descent and still went on to have two VBACs.

I have known women who have had VBACs after 1, 2, and even 3 prior CPD cesareans, including full dilation and pushing for hours each time with no vaginal birth. Yet they still eventually had a VBAC. The International Cesarean Awareness Network (ICAN) has a number of stories of women who have had a prior cesarean (or more) for CPD or Arrest of Descent and yet went on to have a VBAC. You can see some of them in their "Question CPD" video below.

There are never any guarantees, of course, and there are important risks to consider with both VBAC and an Elective Repeat Cesarean. However, if you choose to labor, your VBAC chances are good, anywhere between 50-80% based on the research. Don't let care providers convince you out of trying for a VBAC based on a past history of CPD or Arrest of Descent. In the end, it's your decision.



April is Cesarean Awareness Month. For more information on cesareans and VBACs, see the International Cesarean Awareness Network. 


References

J Matern Fetal Neonatal Med. 2018 Feb 27:1-5. doi: 10.1080/14767058.2018.1443069. [Epub ahead of print] Vaginal birth after a cesarean delivery for arrest of descent. Fox NS, Namath AG, Ali M, Naqvi M, Gupta S, Rebarber A. PMID: 29455594

...This was a retrospective cohort study of all patients delivered by a single MFM practice from 2005 to 2017 with a singleton pregnancy and one prior CD for arrest of descent. We estimated the rate and associated risk factors for successful VBAC. RESULTS: We included 208 patients with one prior CD for arrest of descent, 100 (48.1%) of whom attempted a trial of labor after cesarean (TOLAC) with a VBAC success rate [of] 84/100 (84%, 95% CI 76-90%). Among the women who attempted TOLAC, women with a prior vaginal delivery >24 weeks' had a significantly higher VBAC success rate (91.8% versus 71.8%, p = .01). Maternal age, body mass index, estimated fetal weight, induction of labor, and cervical dilation were not associated with a higher VBAC success rate. CONCLUSIONS: For women with a prior CD for arrest of descent, VBAC success rates are high. This suggests that arrest of descent is mostly dependent on factors unique to each pregnancy and not due to an inadequate pelvis or recurring conditions. Women with a prior CD for arrest of descent should not be discouraged from attempting TOLAC in a subsequent pregnancy due to concerns about the likelihood of success.

J Matern Fetal Neonatal Med. 2017 Feb;30(4):461-465. Epub 2016 May 5. Prolonged second stage in nulliparous with epidurals: a systematic review. Gimovsky AC, Guarente J, Berghella V. PMID: 27050812

...A systematic review of the literature was performed... for case series evaluating the morbidities of prolonged second stage of labor. Search terms used were "prolonged", "second stage", and "labor". Prolonged second stage was defined as three hours or more. Retrospective case series of prolonged second stage in nulliparous women with epidurals were identified. The primary outcome was the incidence of cesarean delivery. RESULTS: Two retrospective series with 5350 nulliparous women with prolonged second stage were identified. 76.3% (4 081/5 350) had an epidural. Of all nulliparous women with an epidural, 11.5% (4 081/35 469) had prolonged second stage. Cesarean Delivery occurred in 19.8% of these cases (782/4 081), while 80.2% had a vaginal delivery. CONCLUSIONS: Over three quarters of nulliparous women with epidural diagnosed with a prolonged second stage deliver vaginally.

VBAC After CPD Diagnosis

J Obstet Gynaecol Can. 2003 Apr;25(4):275-86. Vaginal birth after Caesarean section: review of antenatal predictors of success. Brill Y, Windrim R. PMID: 12679819

"...Even with a history of CPD, two-thirds of women will have successful VBAC, though rates decrease with increasing numbers of prior CS...There are few absolute contraindications to attempted VBAC. Attempted VBAC will be successful in the majority of attempted cases."

Obstetrics and Gynecology. February 1989. 73(2):161-5. Twice A Cesarean, Always a Cesarean? Phelan, JP et al.  PMID: 2911420

[My summary of highlights from the full text] 501 women with 2 or more previous cesareans had a TOL, and 69% had a VBAC overall. Women who had had at least one previous cesarean for CPD had a 64% VBAC rate. Those who had had 2 successive labors both ending in c/s for CPD still had a 56% VBAC rate. In other words, even those women with a previous 'failed' trial of labor had a better chance of a VBAC than another cesarean in labor.

Other Studies on Arrest of Descent or Similar Definitions

• Am J Obstet Gynecol. 2015 Dec;213(6):861.e1-5. doi: 10.1016/j.ajog.2015.08.064. Epub 2015 Sep 6. Effect of stage of initial labor dystocia on vaginal birth after cesarean success. Lewkowitz AK, Nakagawa S, Thiet MP, Rosenstein MG. PMID: 26348381
• Acta Obstet Gynecol Scand. 2013 Feb;92(2):193-7. doi: 10.1111/aogs.12023. Epub 2012 Nov 5. Cervical dilation at the time of cesarean section for dystocia -- effect on subsequent trial of labor. Abildgaard H, Ingerslev MD, Nickelsen C, Secher NJ. PMID: 23025257
• Obstet Gynecol. 2001 Oct;98(4):652-5. Should we allow a trial of labor after a previous cesarean for dystocia in the second stage of labor? Bujold E, Gauthier RJ. PMID: 11576583
• Obstet Gynecol. 2000 Apr;95(4): S38. https://doi.org/10.1016/S0029-7844(00)00660-8 Obstetrics Prognostic indicators for successful vaginal birth after cesarean delivery. Marshak J, Cooperman BS, Fried WB, Shi, Quihu. Available here.
• Br J Obstet Gynaecol. 1998 Oct;105(10):1079-81. Vaginal delivery after previous caesarean section for failure of second stage of labour. Jongen VH, Halfwerk MG, Brouwer WK. PMID: 9800930
• Obstet Gynecol. 1998 Nov;92(5):799-803. First delivery after cesarean delivery for strictly defined cephalopelvic disproportion. Impey L, O'Herlihy C. PMID: 9794672
• Obstet Gynecol. 1997 Apr;89(4):591-3. Correlation between maximum cervical dilatation at cesarean delivery and subsequent vaginal birth after cesarean delivery. Hoskins IA, Gomez JL. PMID: 9083318