External Version for Breech After Prior Cesarean

An External Cephalic Version (ECV, or turning the baby manually to a head-down position) is one option open to people whose babies are breech. However, if you have had a prior cesarean, you may be told that this is not an option for you.

The evidence does not support excluding those with a prior cesarean from an External Cephalic Version. It's time for obstetric societies to update their guidelines about this, and it's time for more providers to routinely offer ECV.

Background

The main benefit of External Cephalic Version is that it is often successful in getting the baby head-down, and a head-down birth is usually less risky than a breech birth.

Although many breech babies can be born vaginally just fine (especially those that meet certain criteria and/or are attended with alternate positioning), there are some increased risks to be aware of.

As a result, many care providers these days strongly prefer a cesarean or even schedule one automatically with a breech baby. Because some areas do not "allow" Vaginal Birth After Cesarean (VBAC), this can mean that all future babies must also be born by cesarean.

Therefore, getting the baby head-down via an External Cephalic Version can help prevent not just the first cesarean, but many automatic repeat cesareans and the serious complications that can happen with them.

Of course, like everything, ECV has both benefits and risks. The risks of ECV include premature labor, placental abruption (placenta detaching too early), hemorrhage, or fetal distress. Although real, these risks are relatively rare, usually less than 1%.

Obviously, sometimes ECV is also contraindicated. Most clinicians agree that ECV should not be attempted in the presence of pre-existing fetal distress, placenta previa, placental abruption, premature rupture of membranes, and certain uterine malformations. Low amniotic fluid levels may also be a relative contraindication.

A good review of the benefits and risks of ECV can be found here. Basically, ECV is able to turn babies head-down most of the time without many complications, and thus prevents many cesareans that would otherwise happen. This is important because cesarean rates are so high; ECV is quite an effective way to reduce the number of cesareans and probably many cases of resulting abnormal placental attachment.

Astonishingly, though, research shows that ECV is not used that much in many areas, despite its relative success rate and potential for lowering the cesarean rate.

Often, doctors don't even tell people that ECV is an option. They just schedule a cesarean and discourage people from exploring other options. One study from New Zealand estimated that only 26% of eligible patients with breech presentations were referred for ECV.

The situation is even worse if you have had a prior cesarean. For those with a scarred uterus, it's even harder to get an ECV because doctors have been taught that it's too dangerous.

The Controversy

People whose babies are breech and have a history of a prior cesarean are often told that ECV is simply not a choice for them because manipulation done during an ECV might make the uterus rupture along the scar from the prior cesarean.

The problem is that there is no actual proof that this is a substantial risk. No study has found this to be a problem, but just the mere fear of the possibility has led to its denial for this group. Currently, you can still find recommendations online that list prior cesarean (or any prior uterine surgery) as a contraindication to even attempting an ECV.

However, a policy of no External Cephalic Version for people with a prior cesarean is not supported by research.

There are a number of studies, including some very recent studies, that suggest that people with a prior cesarean SHOULD have the option to have an External Version if they want it.

The latest study (Weill 2016) had 158 women in the study group and found no increase in complications in the group with a prior cesarean. The success rate of ECV in this group was good (117/158, or 74%), and only 12 of these patients ended up with a cesarean during labor. That means that using ECV in the prior cesarean group prevented 105 automatic repeat cesareans. The authors summarized their findings this way:

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.

Similarly, another recent study (Burgos 2014) found no increased rate of complications in the group with a prior cesarean. The authors concluded:

Uterine scar should not be considered a contraindication and ECV should be offered to women with previous caesarean section with breech presentation at term.

Another study (Abenhaim 2009) also found no increase in complications in those with a prior cesarean who had an ECV. The authors stated:

Concern about procedural success in women with a previous cesarean section is unwarranted and should not deter attempting an external cephalic version.

However, both RCOG (Royal College of Obstetricians and Gynaecologists) and ACOG (American College of Obstetricians and Gynecologists) still hesitate to endorse ECV after prior cesarean. They say that there is not enough research to prove that it is safe. They point out that many of the studies on ECV and prior cesarean are fairly small, which limits their power.

That is a fair point. It's true that most studies have been relatively small and we don't have a huge pool of data to pull from, but taken together the results are quite encouraging.

One older review (Sela 2008) did a search of previous studies to pool the results. They found a total of 124 patients who had an ECV after prior cesarean. They added 42 patients from their own database. Adding in the 36 from the Abenhaim 2009 study, 70 from the Burgos 2014 study, and 158 from the Weill 2016 study, you get a total of 430 patients who have been documented to have an ECV after prior cesarean ─ all without any poor outcomes.

What this means is that there isn't ANY evidence to prove that ECV is unsafe in those with a prior cesarean. While the data pool is still somewhat limited, so far ALL of it supports ECV after prior cesarean.

Yet ACOG's recently revised 2016 guideline on ECV states, "Having had a previous cesarean delivery is not linked with lower rate of success; however, whether it magnifies risk for uterine rupture is not known." They cite only two studies from 1991 and 1998 and state, "Larger studies would be needed to establish the risk of uterine rupture." This ignores all the recent studies on ECV. This cavalier omission will continue to lead many care providers to continue to deny ECV to those with prior cesareans.

Although more research is needed, the bottom line is that the accumulating evidence certainly suggests that an ECV after a prior cesarean is not unduly risky and is a reasonable choice that should be offered to those who want it. 

A more reasonable view of the evidence has led the SOGC (the Canadian version of RCOG and ACOG) to state:

External cephalic version is not contraindicated in women with a previous Caesarean birth.

It's time for ACOG and RCOG to recognize that they are basing their guidelines more on fear than on the latest evidence and update their guidelines accordingly. Bravo to the Canadians for leading the way on this issue.

More research should be done ─ an excellent question is WHY hasn't more been done by now? My best guess is that it reflects the exaggerated fears of the care providers rather than a reasoned response. But given the absence of poor outcomes up till now, research on this topic should be expanded and in the meantime, ECV should be available to those with a prior cesarean.

In addition, it is time for more care providers to offer ECV as an option across the board. This is a sadly underused procedure that could certainly greatly impact cesarean rates and maternal morbidity, both by preventing the first cesarean and lowering the rate of automatic repeat cesareans that follow.


References

External Cephalic Version After Prior Cesarean

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.

J Perinat Med. 2009;37(2):156-60. doi: 10.1515/JPM.2009.006. External cephalic version among women with a previous cesarean delivery: report on 36 cases and review of the literature. Abenhaim HA1, Varin J, Boucher M. PMID: 19021458

AIMS: Whether or not women with a previous cesarean section should be considered for an external cephalic version remains unclear. In our study, we sought to examine the relationship between a history of previous cesarean section and outcomes of external cephalic version for pregnancies at 36 completed weeks of gestation or more. METHODS: Data on obstetrical history and on external cephalic version outcomes was obtained from the C.H.U. Sainte-Justine External Cephalic Version Database. Baseline clinical characteristics were compared among women with and without a history of previous cesarean section. We used logistic regression analysis to evaluate the effect of previous cesarean section on success of external cephalic version while adjusting for parity, maternal body mass index, gestational age, estimated fetal weight, and amniotic fluid index. RESULTS: Over a 15-year period, 1425 external cephalic versions were attempted of which 36 (2.5%) were performed on women with a previous cesarean section. Although women with a history of previous cesarean section were more likely to be older and para >2 (38.93% vs. 15.0%), there were no difference in gestational age, estimated fetal weight, and amniotic fluid index. Women with a prior cesarean section had a success rate similar to women without [50.0% vs. 51.6%, adjusted OR: 1.31 (0.48-3.59)]. CONCLUSION: Women with a previous cesarean section who undergo an external cephalic version have similar success rates than do women without. Concern about procedural success in women with a previous cesarean section is unwarranted and should not deter attempting an external cephalic version. 

Eur J Obstet Gynecol Reprod Biol. 2009 Feb;142(2):111-4. doi: 10.1016/j.ejogrb.2008.08.012. Epub 2008 Nov 18. Safety and efficacy of external cephalic version for women with a previous cesarean delivery. Sela HY, Fiegenberg T, Ben-Meir A, Elchalal U, Ezra Y. PMID: 19019528

OBJECTIVE: To evaluate the success and morbidity rates for attempted external cephalic version (ECV) in patients with one previous cesarean delivery (CD) and a breech-presenting fetus at term. STUDY DESIGN: This is a retrospective study of outcomes of ECV at our institution for all women with one previous CD and a breech-presenting fetus at term between January 1997 and June 2005. A literature review was also performed as a Medline search (1966-2006). RESULTS: ECV was attempted for 42 women with a breech-presenting fetus and previous CD. The success rate of ECV was 74.0%, and 84% of women with successful ECV delivered vaginally. All fetal and maternal outcomes were favorable. Only four Medline reports met our inclusion criteria, representing a total of 124 patients and a mean ECV success rate of 76.6%. Thus we assessed 166 cases of attempted ECV and find an average ECV success rate of 76.5% and favorable fetal and maternal outcomes. CONCLUSIONS: Women with a breech-presenting fetus at term and previous CD, who desire a trial of labor, should be counseled regarding the accumulating evidence about the efficacy and apparently safety of this procedure and may be offered an ECV attempt.

Eur J Obstet Gynecol Reprod Biol. 1998 Oct;81(1):65-8. External cephalic version after previous cesarean section: a series of 38 cases. de Meeus JB1, Ellia F, Magnin G. PMID: 9846717

OBJECTIVE: To determine if external cephalic version (ECV) is a reasonable alternative to repeat cesarean section in case of breech presentation. STUDY DESIGN: Retrospective study of 38 women with one previous cesarean section and a breech presentation after 36 weeks of gestational age who have had at least one experience of ECV. Statistics used the Fisher's test with significance when P<0.05. RESULTS: Version attempts were successful in 25 of the 38 women (65.8%). Seventy-six percent of the successful version women went on to have vaginal birth after cesarean section. A total of 19 successful vaginal deliveries occurred (50%). Success rate of ECV was lowered when breech was the indication of the previous cesarean section. The vaginal delivery rate was increased after successful ECV in patients previously vaginally delivered, but this difference did not reached significance (P=0.057). No maternal or neonatal complications occurred. CONCLUSION: ECV is acceptable and effective in women with a prior low transverse uterine scar, when safety criteria are observed.

Int J Gynaecol Obstet. 1994 Apr;45(1):17-20. External cephalic version after previous cesarean section--a clinical dilemma. Schachter M, Kogan S, Blickstein I. PMID: 7913053

OBJECTIVES: To describe our limited experience with external cephalic version from breech to vertex presentation at term, with the use of ritodrine tocolysis, in women who had undergone a previous cesarean delivery. METHODS: Eleven parturients after previous cesarean delivery underwent external version after 36 gestational weeks, utilizing tocolysis with ritodrine, after excluding cases of low-lying placenta, severe oligohydramnion or ruptured membranes. Patients were then followed until delivery and scar examination was carried out after vaginal delivery, or at re-cesarean section, according to mode of delivery. RESULTS: All 11 attempted versions were successful. Six patients subsequently delivered vaginally and five by re-cesareansection. None of the uterine scars showed any signs of dehiscence. Three of the five infants delivered by re-cesarean section weighed over 4000 g, whereas all of the vaginally-delivered infants weighed under 3500 g. CONCLUSIONS: External cephalic version to vertex presentation after previous cesarean section was successful in all 11 carefully selected patients. No untoward effects were noted, and no signs of scar dehiscence were found. The safety and efficacy of this procedure after previous cesarean delivery should be examined further.

Am J Obstet Gynecol. 1991 Aug;165(2):370-2. External cephalic version after previous cesarean section. Flamm BL, Fried MW, Lonky NM, Giles WS. PMID: 1872341

Approximately 100,000 cesarean sections are performed each year in the United States because of breech presentation. Numerous studies have shown that external cephalic version can eliminate the need for many of these operations. However, because of the fear of uterine rupture, these studies have generally excluded patients who have undergone previous cesarean section. To evaluate the validity of this exclusion policy, we studied patients with one or more previous cesarean sections and breach presentations near term. Version attempts were successful in 82% of 56 patients who had undergone a previous cesarean section. Sixty-five percent of the successful version patients went on to have vaginal birth after cesarean section. There were no serious maternal or fetal complications associated with the version attempts. We conclude that external cephalic version is a reasonable option in patients with prior low transverse cesarean section.

Stop Blaming Women for Cesarean Rates

For many years, the cesarean rate rose, virtually unchecked. When this was questioned, care providers resorted to the old mantra of blaming the women.

At first they said that the cesarean rate was rising because women wanted cesareans to avoid the pain and bother of labor, or for the sake of convenience. The Brits called this being "too posh to push," implying that women were selfish, lazy, and couldn't be bothered to go through labor.

In the U.S., doctors implied that women wanted cesareans for the sake of convenience; they implied the increase in cesareans was simply in response to demands from women themselves.

Of course, there are a few women request elective cesareans, but those women are rare, probably around 1-3%. By and large the cesarean rate was NOT being driven by mother request or because women couldn't be bothered to labor.

When data came out questioning this, doctors started blaming women instead. 

They said the cesarean rate was rising because women were too old, were waiting too long to have babies, were too fat, or were too sick. Numerous articles said that was what was REALLY driving the increase in cesareans. Here is a quote from one Canadian article:

Doctors said several factors are driving the push for surgical births, from fear of pain during childbirth and the convenience factor to the growing proportion of expectant mothers who are obese.

Ugh. I've been arguing against the "women are too fat" argument for years. Fat women have had plenty of babies in the past and the cesarean rate for them then was far lower than it is now. In some studies it was no different than that of average-sized women.

It's not women's size that is directly driving the cesarean rate. Instead what seems to have changed is providers' practice patterns around handling the pregnancies of fat women.

One German study really zeroed in on this by showing that the cesarean rate for obese women had drastically risen over a 12-year period. In the study, the cesarean rate for "morbidly obese" women (BMI over 40) increased from 26.9% in 1990 to 55.2% in 2012. Basically, it doubled.

Critics would argue that the cesarean rate has increased in all groups over time, which is correct. However, it has not increased equally over all groups, suggesting that something about the management of certain groups has changed.

For example, the rate has increased MOST in the women with the highest BMIs. In the German study, the cesarean rate increased 15.3% in the "normal" BMI group, whereas it increased 28.3% in the "morbidly obese" group.

This strongly suggests that it is not obesity itself that is driving the increase, but the way that obese pregnancies are being managed. Obese women are subjected to more interventions, more exaggeration of fear around their pregnancies, and a lowering of the surgical threshold for a cesarean.

But it's not just about blaming obesity. Women are being blamed across the board for higher cesarean rates in order to deflect criticism from how births are being managed these days.

I have written about this topic of mother-blaming for cesarean rates many times. That's why I was delighted recently to see this mother-blaming thoroughly debunked in an article from Australia. (The article is not new; it is from 2012, but I only recently saw it.) It was written by maternity care professionals there. Sadly, they were mostly addressing the cesarean rate in Australia, although they did reference the rates in the U.S. Wish more U.S. providers had the guts to chime in on this issue.

But at least the Australian authors said out loud what few in the obstetric world have been willing to admit until recently ─ that the increase in cesareans has largely been driven by provider practice, not by differences in women themselves.

Here is a quote from the authors (my emphasis):

When we’re not using the “too posh to push” or “asking for it” explanation for rising caesarean rates, health professionals resort to the “too old, too sick and too fat” mantra to explain away our responsibility for the rise. In other words, women are giving birth at older ages, they have more health complications and are increasingly overweight. 

All of this is true on one level – women are older and more likely to be overweight and this all increases the chance of complications – but caesareans are rising among all groups, regardless of age, risk factors and weight...

It’s time to abandon the “too old, too fat, too sick and asking for it” mantra and stop blaming women for the high rates of caesarean births. 

Instead, we need to address the real problem: we health providers are too often scared, impatient and inadequately informed to give women a real choice.

About time someone in the profession is saying what consumers have been saying for years! Yet many in the medical world are still scapegoating women for high cesarean rates.

It is not a matter of a rising tide of high-risk mothers driving up the cesarean rate, but rather a deep and increasing trend towards more intervention and a lower surgical threshold in ALL groups. As Henci Goer and CNM Amy Romano note in their book, "Optimal Care in Childbirth":

U.S. cesarean rates have increased sharply at every maternal age, in every ethnic group, and for every demographic or medical risk factor.

By blaming mothers, caregivers avoid taking responsibility for their own actions which have pushed up the cesarean rate. 

The induction and "pushed birth" epidemic, the over-intervention in normal labors, the lack of support for vaginal breech birth, the virtual abandonment of VBAC, the loss of skills in manually turning poorly-positioned babies, the lack of patience during labor, the increasingly narrow definition of "normal," the fear around lawsuits, and the lowering of surgical thresholds have all been caregiver-driven reasons for the rise in the cesarean rate.

The conversation needs to stop being about mother-blaming. It should be about caregivers taking responsibility for the patterns of management that have driven up cesarean rates over the years. Providers have conveniently managed to deflect this for years by blaming women instead of turning a critical eye to their own practices, but this must end.

Changing demographics may play a small role and women do have a responsibility to be proactive in their health habits to minimize the risk for complications, but providers need to acknowledge that the way they manage births has been a very significant factor in the tremendous rise in the cesarean rate.

It's time to stop scapegoating women for the high cesarean rate, and it's time for caregivers to take responsibility for their own contributions to the high cesarean rate.

References

Am J Public Health. 2006 May;96(5):867-72. Epub 2006 Mar 29. Maternal risk profiles and the primary cesarean rate in the United States, 1991-2002. Declercq E, Menacker F, Macdorman M. PMID: 16571712

OBJECTIVES: We examined factors contributing to shifts in primary cesarean rates in the United States between 1991 and 2002. METHODS: US national birth certificate data were used to assess changes in primary cesarean rates stratified according to maternal age, parity, and race/ethnicity. Trends in the occurrence of medical risk factors or complications of labor or delivery listed on birth certificates and the corresponding primary cesarean rates for such conditions were examined. RESULTS: More than half (53%) of the recent increase in overall cesarean rates resulted from rising primary cesarean rates. There was a steady decrease in the primary cesarean rate from 1991 to 1996, followed by a rapid increase from 1996 to 2002. In 2002, more than one fourth of first-time mothers delivered their infants via cesarean. Changing primary cesarean rates were not related to general shifts in mothers' medical risk profiles. However, rates for virtually every condition listed on birth certificates shifted in the same pattern as with the overall rates. CONCLUSIONS: Our results showed that shifts in primary cesarean rates during the study period were not related to shifts in maternal risk profiles.

PLoS Med. 2014 Oct 21;11(10):e1001745. doi: 10.1371/journal.pmed.1001745. eCollection 2014. Maternal clinical diagnoses and hospital variation in the risk of cesarean delivery: analyses of a National US Hospital Discharge Database. Kozhimannil KB1, Arcaya MC2, Subramanian SV2. PMID: 25333943

BACKGROUND: Cesarean delivery is the most common inpatient surgery in the United States, where 1.3 million cesarean sections occur annually, and rates vary widely by hospital. Identifying sources of variation in cesarean use is crucial to improving the consistency and quality of obstetric care. We used hospital discharge records to examine the extent to which variability in the likelihood of cesarean section across US hospitals was attributable to individual women's clinical diagnoses. METHODS AND FINDINGS: Using data from the 2009 and 2010 Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project--a 20% sample of US hospitals--we analyzed data for 1,475,457 births in 1,373 hospitals. We fitted multilevel logistic regression models (patients nested in hospitals). The outcome was cesarean (versus vaginal) delivery. Covariates included diagnosis of diabetes in pregnancy, hypertension in pregnancy, hemorrhage during pregnancy or placental complications, fetal distress, and fetal disproportion or obstructed labor; maternal age, race/ethnicity, and insurance status; and hospital size and location/teaching status. The cesarean section prevalence was 22.0% (95% confidence interval 22.0% to 22.1%) among women with no prior cesareans. In unadjusted models, the between-hospital variation in the individual risk of primary cesarean section was 0.14 (95% credible interval 0.12 to 0.15). The difference in the probability of having a cesarean delivery between hospitals was 25 percentage points. Hospital variability did not decrease after adjusting for patient diagnoses, socio-demographics, and hospital characteristics (0.16 [95% credible interval 0.14 to 0.18]). A limitation is that these data, while nationally representative, did not contain information on parity or gestational age. CONCLUSIONS: Variability across hospitals in the individual risk of cesarean section is not decreased by accounting for differences in maternal diagnoses. These findings highlight the need for more comprehensive or linked data including parity and gestational age as well as examination of other factors-such as hospital policies, practices, and culture--in determining cesarean section use. 

J Perinat Med. 2014 Jun 10. Impact of maternal body mass index on the cesarean delivery rate in Germany from 1990 to 2012. Kyvernitakis I, Köhler C, Schmidt S, Misselwitz B, Großmann J, Hadji P, Kalder M. PMID: 24914711

ABSTRACT AIMS: Maternal obesity is a risk factor for cesarean delivery (CD). The aim of this analysis was to determine the association between early-pregnancy body mass index (BMI) and the rate of CD over the past two decades. METHODS: We retrospectively analyzed data from the perinatal quality registry of singleton deliveries in the state of Hesse in Germany from 1990 to 2012. We divided the patients into groups according to the WHO criteria for BMI: underweight (<18.5), normal weight (18.5-<25), overweight (25-<30), obese class I (30-<35), obese class II (35-<40), and obese class III (≥40). RESULTS: The analysis included 1,092,311 patients with available data regarding maternal BMI and mode of delivery. The CD rates for underweight (<18.5), normal weight (18.5-<25), overweight (25-<30), obese class I (30-<35), obese class II (35-<40), and obese class III (≥40) women increased from 14.4%, 16.1%, 19.5%, 22.3%, 25%, and 26.9% in the year 1990 to 27.9%, 31.4%, 38.8%, 45.1%, 50.2%, and 55.2% in the year 2012, respectively (P<0.001). CONCLUSION: Maternal BMI in early pregnancy is linearly associated with the incidence of CD. We found a disproportionate increase of CD in morbidly obese women compared with the CD incidence in the reference BMI population over the past two decades.

J Obstet Gynaecol Can. 2011 May;33(5):443-8. Higher caesarean section rates in women with higher body mass index: are we managing labour differently? Abenhaim HA, Benjamin A. PMID: 21639963

BACKGROUND: Higher body mass index has been associated with an increased risk of Caesarean section. The effect of differences in labour management on this association has not yet been evaluated. METHODS: We conducted a cohort study using data from the McGill Obstetrics and Neonatal Database for deliveries taking place during a 10-year period. Women's BMI at delivery was categorized as normal (20 to 24.9), overweight (25 to 29.9), obese (30 to 39.9), or morbidly obese (≥ 40). We evaluated the effect of the management of labour on the need for Caesarean section using unconditional logistic regression models. RESULTS: Data were available for 11 922 women, of whom 2289 women had normal weight, 5663 were overweight, 3730 were obese, and 240 were morbidly obese. After adjustment for known confounding variables, increased BMI category was associated with an overall increase in the use of oxytocin and in the use of epidural analgesia, and with a decrease in use of forceps and vacuum extraction among second stage deliveries. Higher BMI was also found to be associated with earlier decisions to perform a Caesarean section in the second stage of labour. When adjusted for these differences in the management of labour, the increasing rate of Caesarean section observed with increasing BMI category was markedly attenuated (P < 0.001). CONCLUSION: Women with an increased BMI are managed differently in labour than women of normal weight. This difference in management in part explains the increased rate of Caesarean section observed with higher BMI.