Induction: Don't Break The Waters Early

Amnihooks, which are used to artificially break a woman's waters

New research (Pasko 2018) suggests that when care providers induce high BMI women, they should NOT break the waters in early labor (early amniotomy), especially in first-time mothers.

Breaking the waters early is commonly done to speed up labor. Sometimes it is done to place an internal monitor to monitor the baby more easily, but usually it is used to intensify contractions and shorten labor. Caregivers assume that this will help obese women avoid a cesarean.

However, the results from this new study suggest that early amniotomy actually increases the risk for a cesarean instead.

Study Details

In this retrospective cohort study, women with Class III "obesity" (body mass index ≥40 kg/m2) who were being induced  (n=285) were placed into two groups.

The first group (n=107) received early amniotomy before 4 cm dilation, and the other group (n=178) received late amniotomy.

The group who received early amniotomy had double the cesarean risk of those who did received later amniotomy.

In first-time (nulliparous) mothers, the risk for cesarean was tripled with early amniotomy. 

The length of labor was not shortened in either group. So the whole justification for using early amniotomy (shorter labor, fewer cesareans) for obese women was irrelevant.

An older study (Sheiner 2000) which examined induction by early amniotomy concluded:

In order to decrease the CS rates, induction should probably start with cervical ripening techniques in order to improve the Bishop scores.

Bishop Scores are a measure of how ripe and ready for labor the cervix is. Inductions on an unripe cervix are more likely to fail and result in cesarean, especially in first-time moms. Bishop scores tend to be lower at the start of inductions in women of size, which is probably an important factor in higher weight women's induction failures. 

Women of size also tend to have longer labors and generally take longer in latent (early) labor before reaching active labor. Yet despite this, research shows that early amniotomy is used more often in higher weight women. This needs to change.

How can early amniotomy (also known as Artificial Rupture of Membranes or early AROM) affect labor? When the water is broken, the cushioning around the baby is removed. Labor becomes much more painful, and there is risk for infection. The baby may be more likely to experience an abnormal heart rate (distress). If the baby is not well-positioned when AROM occurs, then the baby can become stuck in that position and have difficult getting out (labor dystocia). These factors can add up and result in a cesarean.

The take-home message from this study on high BMI women is obvious: Avoid having your waters broken before active labor begins (now defined as at least 6 cm dilation). This is especially important if you are a first-time mother. 

Of course, parents have to remain flexible in labor; plans may need to change. For example, if baby may be in trouble and external monitoring is not working well, then breaking the water sooner to place an internal monitor may make sense. But most of the time, amniotomy should not be done early in labor, especially in obese first-time mothers.

Induction Hints

It is best to await spontaneous labor whenever possible, so always question whether an induction is truly necessary. However, it's a hard truth that sometimes induction of labor does become medically necessary. If so, there are some lessons from research that may lessen your risk for cesarean. Most apply to women of all sizes but may be particularly relevant for higher weight women.

Ask your provider about your Bishop Score; if your cervix isn't ripe (Bishop score <5), ask if the induction can be delayed. If it cannot be delayed, ask for techniques to help ripen the cervix before pitocin is started and realize that you may need more time to reach active labor. Some research suggests that Foley catheter or prostaglandin (PGE2) inductions may be more effective in women of size than misoprostol (Cytotec).

Women of size may also need a larger dose of pitocin to keep an induced labor going strong, but this must be done cautiously because too much pitocin can send the baby into fetal distress. Wait and see how you and baby respond before increasing the dosage and go slowly with any adjustments.

Be sure you have a care provider who understands that latent labor tends to take longer in higher weight women and will give you plenty of time. Many cesareans in women of size are done before active labor, and many could probably be prevented if caregivers were more patient and waited longer before moving to a cesarean.

Be sure your baby is in an optimal position for birth before the induction if possible. Chiropractic care may help align the pelvis and maximize the space for an easier birth. If the baby is posterior (facing your front) in labor, ask your caregiver for manual rotation, which clearly reduces the risk for cesarean in several studies.

Maintain your mobility as much as possible and don't get stuck in bed on your back. Make gravity work for you. Upright positions reduce the length of labor and the risk for cesarean. Special positions like hands and knees or an exaggerated Sims position may help malpositioned babies turn more easily. You can read more aboutvarious labor and birth positions here.

As discussed, don't let the caregivers break the waters until you are well into active labor. If possible, let the waters break on their own. Keeping the waters intact as long as possible can help a malpositioned baby turn more easily.

Hire a doula to give professional labor support. One study found a cesarean rate of 13.4% in a group of first-time mothers with doulas, whereas the cesarean rate in the group without doulas was 25%. The difference was even more marked in those whose labors were induced; the group with doulas had a cesarean rate of 12.5%, vs. a 58.8% rate in those without doulas.

These ideas should improve your chances of a normal vaginal birth with an induction. Of course there are no guarantees, but rest assured that with enough time and patience, a reasonably ripe cervix, a well-positioned baby, and good support, many inductions in women of size can result in vaginal births.

Reference

Am J Perinatol. 2018 Nov 5. doi: 10.1055/s-0038-1675331. [Epub ahead of print] Pregnancy Outcomes after Early Amniotomy among Class III Obese Gravidas Undergoing Induction of Labor. Pasko DN, Miller KM, Jauk VC, Subramaniam A.  PMID: 30396229 

OBJECTIVE: We sought to evaluate differences in pregnancy outcomes following early amniotomy in women with class III obesity (body mass index ≥40 kg/m2) undergoing induction of labor. STUDY DESIGN: This is a retrospective cohort study of women with class III obesity undergoing term induction of labor from January 2007 to February 2013. Early amniotomy was defined as artificial membrane rupture at less than 4 cm cervical dilation. The primary outcome was cesarean delivery. Secondary outcomes included length of labor, a maternal morbidity composite, and a neonatal morbidity composite. A subgroup analysis examined the effect of parity. Multivariable logistic regression was used to adjust for covariates. RESULTS: Of 285 women meeting inclusion criteria, 107 (37.5%) underwent early amniotomy and 178 (62.5%) underwent late amniotomy. Early amniotomy was associated with cesarean delivery after multivariable adjustments (adjusted odds ratio [aOR], 2.05; 95% confidence interval [CI], 1.21-3.47). There were no significant differences in length of labor or maternal and neonatal morbidity between groups. When stratified by parity, early amniotomy was associated with increased cesarean delivery (aOR, 3.10; 95% CI, 1.47-6.58) only in nulliparous women. CONCLUSION: Early amniotomy among class III obese women, especially nulliparous women, undergoing labor induction may be associated with an increased risk of cesarean delivery.

Hospitals with Midwives on Staff Have Better Outcomes

Here are two recent studies showing that hospitals with midwives and doctors practicing together ("interprofessional" centers) have better outcomes than hospitals with only doctors. One study is on first-time mothers (nulliparous), and the other study is on women who have given birth before (multiparous), to separate out the possible effects of parity.

In first-time mothers, women were much less likely to be induced or have oxytocin augmentation of labor in interprofessional/collaborative centers. The cesarean rate was 12% lower in interprofessional centers too.

For multiparous mothers (multips), women were again much less likely to be induced or have augmentation of labor in interprofessional centers. The first-time cesarean rate was 36% lower, and the Vaginal Birth After Cesarean (VBAC) rate was 31% higher than in institutions with only doctors. Neonatal outcomes were similar between the two types of centers.

The implication here is that not only do midwives lower the rates of interventions without endangering outcomes, they also influence the hospital culture in a positive way. Doctors who work with midwives tend to be more flexible about interventions, less likely to push a cesarean without need, and more likely to support VBACs.

If you are considering a hospital birth, try to choose a hospital with both doctors and midwives on staff, one with low overall cesarean rates, and strongly consider hiring a doula for professional labor support. Most women can safely be attended by a midwife, so make that your first choice if you can. If a risk comes up that means that you need to see an OB or high-risk maternal fetal medicine (MFM) specialist, the midwife will refer you to one, probably one that is supportive of the parents' birth wishes whenever conditions allow.



References

Birth. 2018 Nov 11. doi: 10.1111/birt.12407. [Epub ahead of print] Midwifery presence in United States medical centers and labor care and birth outcomes among low-risk nulliparous women: A Consortium on Safe Labor study. Neal JL, Carlson NS, Phillippi JC, Tilden EL, Smith DC, Breman RB, Dietrich MS, Lowe NK. PMID: 30417436

...Our objective was to compare labor processes and outcomes for low-risk nulliparous women birthing in United States medical centers with interprofessional care (midwives and physicians) versus noninterprofessional care (physicians only). METHODS: We conducted a retrospective cohort study using Consortium on Safe Labor data from low-risk nulliparous women who birthed in interprofessional (n = 7393) or noninterprofessional centers (n = 6982). .. women at interprofessional medical centers, compared with women at noninterprofessional centers, were 74% less likely to undergo labor induction (risk ratio [RR] 0.26; 95% CI 0.24-0.29) and 75% less likely to have oxytocin augmentation (RR 0.25; 95% CI 0.22-0.29). The cesarean birth rate was 12% lower at interprofessional centers (RR 0.88; 95% CI 0.79-0.98). Adverse neonatal outcomes occurred in only 0.3% of births and were thus too rare to be modeled. CONCLUSIONS: The care processes and birth outcomes at interprofessional and noninterprofessional medical centers differed significantly. Nulliparous women receiving care at interprofessional centers were less likely to experience induction, oxytocin augmentation, and cesarean than women at noninterprofessional centers. Labor care and birth outcome differences between interprofessional and noninterprofessional centers may be the result of the presence of midwives and interprofessional collaboration, organizational culture, or both.

Birth. 2018 Nov 9. doi: 10.1111/birt.12405. [Epub ahead of print] Influence of midwifery presence in United States centers on labor care and outcomes of low-risk parous women: A Consortium on Safe Labor study. Carlson NS, Neal JL, Tilden EL, Smith DC, Breman RB, Lowe NK, Dietrich MS, Phillippi JC. PMID: 30414200

...We sought to use national United States data to analyze the association between midwifery presence in maternity care teams and the birth processes and outcomes of low-risk parous women. METHODS: We conducted a retrospective cohort study using Consortium on Safe Labor data from low-risk parous women in either interprofessional care (n = 12 125) or noninterprofessional care centers (n = 8996). .. women at interprofessional centers, compared with women at noninterprofessional centers, were 85% less likely to have labor induced (risk ratio [RR] 0.15; 95% CI 0.14-0.17). The risk for primary cesarean birth among low-risk parous women was 36% lower at interprofessional centers (RR 0.64; 95% CI 00.52-0.79), whereas the likelihood of vaginal birth after cesarean for this population was 31% higher (RR 1.31; 95% CI 1.10-1.56). There were no significant differences in neonatal outcomes. CONCLUSIONS: Parous women have significantly higher rates of vaginal birth, including vaginal birth after cesarean, and lower likelihood of labor induction when cared for in centers with midwives. Our findings are consistent with smaller analyses of midwifery practice and support integrated, team-based models of perinatal care to improve maternal outcomes.

Lower Surgical Threshold, Less Patience in Labor for "Obese" Women

Here is yet another study (Ellekjear 2017) showing that labor is often managed differently in "obese" women, with a lower surgical threshold being the most marked finding. The authors concluded:

Caesarean deliveries are undertaken earlier in obese women compared to normal weight women following the onset of active labour, shortening the total duration of active labour.

Research generally shows women of size probably need more time in labor in general, especially in the early stages, but once their labors get going, they usually go well. However, many care providers opt to terminate labor earlier and move quickly to a cesarean. They are understandably concerned about the risks of doing an emergent cesarean on a larger body, but they are usually giving up far too soon and causing an epidemic of "failure to wait" cesareans in women of size. .

There was an infamous Vaginal Birth After Cesarean (VBAC) and obesity study in 2001 that demonstrated this quite strongly. 30 women over 300 lbs. were "allowed" to labor for a VBAC, but only 13% of those who tried for a VBAC ended up with one. As a result, this was widely publicized as a reason not to "let" high-BMI women try for a VBAC and cited by doctors as a reason to deny fat women the opportunity to VBAC.

However, what the full text of the study actually reveals is that the majority of these women were induced, which is known to increase the chances of cesarean and lower the chances of VBAC. Interestingly, the only women who got a VBAC in this study were the ones who were not induced.

Most tellingly, those who had cesareans had their labors stopped at an average of 4.5 cm of dilation. 4.5 cm barely qualifies for the old definition of active labor, and certainly doesn't fit with the new recommended definition of active labor (6 cm)! In other words, these high BMI women were not given an adequate chance to labor.

High induction rates and a lack of patience in labor are the main factors that drive the high cesarean rate in obese women. 

Studies have shown that about half of high BMI women in general are induced, typically increasing cesarean rates. However, when allowed to go into spontaneous labor, cesarean rates are more equalized among BMI groups.

One earlier study found that high BMI women tended to take longer to progress in labor, especially between 4 and 7 cm of dilation. They urged far more patience in the labors of heavier patients.

Similarly, a 2016 study found that 57% of labors in high BMI first-time mothers were stopped before 6 cm of dilation; those mothers ended with cesareans. Failure to Wait is a major problem when doctors attend women of size.

More spontaneous labor and more time during labor would probably have yielded far better VBAC rates in that 2001 VBAC study. It should be pointed out that a look at some later studies showed VBAC rates around 50-70% in obese women, which could almost certainly be increased even more since they also reflect very high induction rates and the old active labor definition. Indeed, research from England shows that the majority of even very high BMI women can have a vaginal birth with different management.

The bottom line is that multiple studies have found that the labors of high BMI women are managed differently than the labors of average-sized women. 

In particular, too many inductions are being done, the surgical threshold is very low, and more patience is needed during labor. This represents an area that is ripe for change and offers hope for lowering the far-too-high cesarean rate in obese women. 

As the authors of a Canadian study concluded about the management of high BMI women:

Because of the potential morbidities associated with Caesarean section, we must modify our management approaches to allow equal opportunity for a vaginal birth for all women.

Reference

BMC Pregnancy Childbirth. 2017 Jul 12;17(1):222. doi: 10.1186/s12884-017-1413-6. Maternal obesity and its effect on labour duration in nulliparous women: a retrospective observational cohort study. Ellekjaer KL, Bergholt T, Løkkegaard E. PMID: 28701155

...METHODS: Retrospective observational cohort study of 1885 nulliparous women with a single cephalic presentation from 37 0/7 to 42 6/7 weeks of completed gestation and spontaneous or induced labour at Nordsjællands Hospital, University of Copenhagen, Denmark, in 2011 and 2012. Total duration of labour and the first and second stages of labour were compared between early-pregnancy normal-weight (BMI <25 kg/m2), overweight (BMI 25-29.9 kg/m2), and obese (BMI ≥30 kg/m2) women. Proportional hazards and multiple logistic regression models were applied. RESULTS: Early pregnancy BMI classified 1246 (66.1%) women as normal weight, 350 (18.6%) as overweight and 203 (10.8%) as obese. No difference in the duration of total or first stage of active labour was found for overweight (adjusted HR = 1.01, 95% CI 0.88-1.16) or obese (adjusted HR = 1.07, 95% CI 0.90-1.28) compared to normal weight women. Median active labour duration was 5.83 h for normal weight, 6.08 h for overweight and 5.90 h for obese women. The risk of caesarean delivery increased significantly for overweight and obese compared to normal weight women (odds ratios (OR) 1.62; 95%CI 1.18-2.22 and 1.76; 95%CI 1.20-2.58, respectively). Caesarean deliveries were performed earlier in labour in obese than normal-weight women (HR = 1.80, 95%CI 1.28-2.54). CONCLUSION: BMI had no significant effect on total duration of active labour. Risk of caesarean delivery increased with increasing BMI. Caesarean deliveries are undertaken earlier in obese women compared to normal weight women following the onset of active labour, shortening the total duration of active labour.

Reducing Failure-to-Wait Cesareans

A while ago, experts developed guidelines to help reduce "failure to progress" cesareans, called the Consensus for the Safe Prevention of the Primary Cesarean Delivery. Among other things, they changed the definition of active labor from 4 cm to 6 cm and encouraged providers to wait longer before resorting to a cesarean in order to reduce "arrest of dilation" cesareans.

But would these new guidelines actually translate into lower cesarean rates in real life? Here is a study at a single academic medical center which compared the cesarean rate in induced or augmented first-time moms before and after the guidelines were implemented. Would the new guidelines result in a meaningful decline in primary cesarean rates? Would outcomes be improved?

In a nutshell, yes, the cesarean rate was definitely lowered and outcomes improved. The cesarean rate in induced or augmented women dropped from 35.5% to 24.5%, and the overall cesarean rate dropped from 26.9% to 18.8%. And indeed, maternal morbidity was reduced.

Of course, because the new guidelines are very recent, the study size is limited. More research is needed to confirm that this change is helpful. But this study is very encouraging that indeed, many primary cesareans can be prevented with just a little bit more patience and time.

Now let's apply these lessons to the labors of "obese" women too. I would love to see a study that looked specifically at whether more time and patience in labor in high-BMI women could lower the rate of primary cesareans in this group too. My guess is that it would, since research shows that we tend to have longer first stages of labor and that care providers are often too quick to surgically intervene in the labors of high-BMI women. But wouldn't it be nice if we had research proving that more patience for women of size was helpful?


Reference

Obstet Gynecol. 2016 Jul;128(1):145-52. doi: 10.1097/AOG.0000000000001488. Reduction in the Cesarean Delivery Rate After Obstetric Care Consensus Guideline Implementation. Wilson-Leedy JG1, DiSilvestro AJ, Repke JT, Pauli JM. PMID: 27275806 DOI: 10.1097/AOG.0000000000001488

OBJECTIVE: To evaluate the rate of primary cesarean delivery after adopting labor management guidelines. METHODS: This is a before-after retrospective cohort study at a single academic center. This center adopted guidelines from the Consensus for the Prevention of the Primary Cesarean Delivery. Nulliparous women attempting vaginal delivery with viable, singleton, vertex fetuses were included. For the primary outcome of cesarean delivery rate among induced or augmented patients, 200 consecutive women managed before guideline adoption were compared with 200 similar patients afterward. Secondary outcomes of overall cesarean delivery rate, maternal morbidity, neonatal outcomes, and labor management practices were analyzed with inclusion of intervening spontaneously laboring women. RESULTS: Between September 13, 2013, and September 28, 2014, 275 women preguideline and 292 postguideline were identified to include 200 deliveries after induction or augmentation each. Among women delivering after induction or augmentation, the cesarean delivery rate decreased from 35.5% to 24.5% (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.38-0.91). The overall cesarean delivery rate decreased from 26.9% to 18.8% (adjusted OR 0.59, CI 0.38-0.92). Composite maternal morbidity was reduced (adjusted OR 0.66, CI 0.46-0.94). The frequency of cesarean delivery documenting arrest of dilation at less than 6 cm decreased from 7.1% to 1.1% postguideline (n=182 and 176 preguideline and postguideline, respectively, P=.006) with no change in other indications.  CONCLUSION: Postguideline, the cesarean delivery rate among nulliparous women attempting vaginal delivery was substantially reduced in association with decreased frequency in the diagnosis of arrest of dilation at less than 6 cm.

Most Babies Suspected to be Large Actually Aren't

So many mothers get the "big baby" fear card handed to them during pregnancy. This often leads to pressure for interventions such as induction of labor, or scaring women into a planned cesarean.

In this survey, one-third of women surveyed were told their babies were getting "quite large." Yet only one in five of these women actually went on to have large babies (around 9 lbs. or more).

Although the survey doesn't have information specifically about women of size, I would bet that the rate of big baby fear cards is even higher in our care. There is some justification for this; on average, we do tend to have somewhat larger babies. But even so, most high-BMI women have average-sized babies. And even if they do have a bigger baby, most of these can be born just fine with a little care and patience, especially if they have full mobility during labor.

But the fear of big babies from big mothers is so exaggerated these days that many care providers act as if every high-BMI woman will have a Godzilla Baby. Sadly, a great deal of the increased interventions we experience is likely tied to that fear of big babies.


Reference

Matern Child Health J. 2015 Dec;19(12):2578-86. doi: 10.1007/s10995-015-1776-0. Labor and Delivery Experiences of Mothers with Suspected Large Babies. Cheng ER1, Declercq ER2, Belanoff C3, Stotland NE4, Iverson RE5. PMID: 26140835

OBJECTIVE: To characterize the prevalence of and factors associated with clinicians' prenatal suspicion of a large baby; and to determine whether communicating fetal size concerns to patients was associated with labor and delivery interventions and outcomes. METHODS: We examined data from women without a prior cesarean who responded to Listening to Mothers III, a nationally representative survey of women who had given birth between July 2011 and June 2012 (n = 1960). We estimated the effect of having a suspected large baby (SLB) on the odds of six labor and delivery outcomes. RESULTS: Nearly one-third (31.2%) of women were told by their maternity care providers that their babies might be getting "quite large"; however, only 9.9% delivered a baby weighing ≥4000 g (19.7% among mothers with SLBs, 5.5% without). Women with SLBs had increased adjusted odds of medically-induced labor (AOR 1.9; 95% CI 1.4-2.6), attempted self-induced labor (AOR 1.9; 95% CI 1.4-2.7), and use of epidural analgesics (AOR 2.0; 95% CI 1.4-2.9). No differences were noted for overall cesarean rates, although women with SLBs were more likely to ask for (AOR 4.6; 95% CI 2.8-7.6) and have planned (AOR 1.8; 95% CI 1.0-4.5) cesarean deliveries. These associations were not affected by adjustment for gestational age and birthweight. CONCLUSIONS FOR PRACTICE: Only one in five US women who were told that their babies might be getting quite large actually delivered infants weighing ≥4000 g. However, the suspicion of a large baby was associated with an increase in perinatal interventions, regardless of actual fetal size.

Induction's Relationship to Cesareans in High BMI Women

Many providers are so affected by the over-hyping of risk around pregnancy in women of size that they routinely induce labor in "obese" women for basically no other real reason than the woman's BMI.

But a recently-published Canadian study shows there is yet another reason to be cautious about routinely inducing labor in obese women─ an increased risk of cesarean.

Yet the authors completely missed the obvious take-home message from their study ─ reduce the number of inductions done in obese women ─ and instead call for more weight-loss intervention efforts in order to prevent cesareans. Doh!

As part of Cesarean Awareness Month, let's take yet another look at the relationship between induction of labor and high cesarean rates in obese women.

Caregivers interested in lowering cesarean rates in higher-weight women would likely get the most effective results by changing management of this group rather than focusing on weight loss efforts.

When will caregivers finally clue in to the fact that they need other tools in the cesarean prevention toolbox besides weight loss? Changing their own management behaviors is the key to lowering cesarean rates in obese women, not getting women all to "normalize" their pre-pregnancy weight.

Let's be clear. It's reasonable to encourage healthy eating and regular exercise in women before they conceive, but that doesn't usually result in significant weight loss. Research shows that only a small percentage of people lose a substantial amount of weight and keep it off. It's unrealistic to insist that women all reach a certain BMI before pregnancy. And it's incredibly foolish to hang all your hopes for lowering cesarean rates on that goal.

There are other, more powerful tools in the toolbox for that. First and foremost among them is changing behaviors around induction of labor in this group.

Background

Induction is a very common intervention used in women of size, as I have pointed out many times before. And there is quite a bit of research suggesting that induction is tied to a higher cesarean rate, especially in first-time mothers or in women with an unripe cervix.

Of course, it's only fair to point out that sometimes induction really is needed in women of size. High-BMI women have a higher rate of pre-eclampsia (blood pressure issues), for example, as this study also found. This often necessitates early induction of labor because pre-eclampsia is very serious and can harm both mother and baby.

But high-BMI women are often induced at far higher rates than their complications justify.

Often these inductions are done for "soft" reasons that are highly questionable medically.

For example, many providers induce labor in obese women because they are afraid of big babies, even though research shows that inducing labor does not improve outcomes at all and often worsens them. The combination of obese first-time mother, a suspected big baby, and induction of labor is particularly potent, doubling the risk for cesarean even in a usually low-intervention midwifery practice.

Often providers induce labor because they believe that pregnancy in a fat woman is a disaster waiting to happen, and that labor should be brought on as soon as possible before an emergency occurs. Sadly, all too often, such perceptions often become self-fulfilling prophecies because of the huge amount of interventions employed, which also carry significant risk.

Some providers induce labor because they mistakenly believe that fat women are unlikely to go into labor on their own. Research shows that higher-weight women do have many inductions for "post-dates" pregnancies and that these inductions are more likely to result in cesareans, but rarely do care providers adjust a high-BMI mother's due date to reflect the fact that many have longer menstrual cycles.

Some induce labor in the belief that fat women are too out of shape to endure a natural labor and birth. Others induce labor because they mistakenly believe inducing labor is the only way that higher weight women will have any chance at having a vaginal birth because of ""fat pads" in the pelvis" or a "fat" vagina. These assumptions are all wrong, mind, but subtle bias like this influences how higher-weight women are managed.

For these and many other reasons, providers tend to over-use inductions in women of size. Although most in the medical field never question the high utilization of inductions in obese women, there are finally now a few researchers who have begun to question this practice.

New Study Findings

A new Canadian study highlights just how many obese women have their labor induced.

Less than a third of average-weight women in the study had their labor induced, but almost HALF of higher weight women had their labor induced. No doubt some of those inductions in the high-BMI group were medically justified, but chances are that many more were not.

Most notably, this study shows that induction in obese women often leads to cesareans.

I've been saying for years that over-use of induction in obese women is one of the main reasons for a high cesarean rate in this group, yet few researchers have bothered to look at this connection or to call for fewer inductions in this group. Many ignore their own findings that inductions are tightly tied to cesarean rates in this group. Finally, now, some researchers are beginning to pay attention.

Of particular note, this Canadian study found that when covariates were controlled for, Body Mass Index (BMI) was not a significant risk factor for cesareans in women with spontaneous labor. 

This is in contrast to the false belief among many providers that obesity often prevents vaginal birth due to "soft tissue dystocia." But in this study, higher weight alone did NOT raise the risk for cesarean ─ when labor was spontaneous.

However, obesity DOUBLED the risk for cesareans during inductions. According to the study:

Obese women were twice more likely (aOR 2.2, CI 1.2-4.1) to deliver by emergency C-section if their labour was induced...The twofold increase in the risk of C-section rates in obese women after induction was independent of pregnancy complications, parity, prior caesarean deliveries, chronic maternal health conditions, treatments for infertility, or maternal age.

That's a really important distinction. A higher weight itself did not increase the risk for cesareans when labor was spontaneous, but when labor was induced, it did. And this was independent of pregnancy complications and other factors that might also increase the risk for cesarean.

This suggests that induction itself (and decision-making during induction) was more of a real factor than the obesity itself.

For example, previous studies have found a lower threshold for surgical intervention in high-BMI patients. Many obese women would probably benefit from their caregivers simply waiting longer before opting for a cesarean. Others would probably benefit more from caregivers waiting for the mother's cervix to be fully ripe before labor was induced.

But most likely, obese women would probably benefit MOST from a lower induction rate. 

Sometimes, induction truly is necessary, and women of size do have higher rates of some complications that make induction a consideration. But many women of size are being induced for dubious reasons, mostly reflecting subtle provider bias and fear rather than true medical indications. These "soft" inductions need to STOP. If inductions are used, they should ideally wait until the cervix is ripe and caregivers should employ more patience in labor before resorting to a cesarean.

Lowering the number of inductions done and changing the management of inductions when they are done should help lower the outrageously high cesarean rates in obese women.

Focus on Realistic Change

To summarize, several recent studies have observed that caregivers often use a high rate of interventions during labor with their obese patients and have questioned whether this is truly beneficial. The authors of this recent Canadian study also noted that:

Even among women with term, singleton pregnancies obtaining prenatal care in community-based settings, obese women who undergo labour induction are at increased risk of obstetrical interventions at delivery...Although obesity in pregnancy is not an independent justification for labour induction, obese women are more likely to be induced and if induced are more likely to undergo delivery by C-section.

Astoundingly, the authors of the Canadian study then completely missed the mark in evaluating their findings. Like many in the obstetrical field, their response was NOT to call for fewer inductions, but rather to call for increased weight loss interventions prior to pregnancy.

What?!?!? Once again, the researchers missed a tremendous opportunity for improving outcomes in higher-weight women because they can't see beyond their own relentless focus on weight loss.

Rather than focusing their efforts on the unlikely success of weight-loss interventions, caregivers should be focusing on lowering the induction rate in this group and changing their threshold for surgical intervention. 

THOSE are the interventions most likely to bring about fewer cesareans.

Several studies have found that inductions are tightly tied to elevated cesarean rates in high-BMI women, and when induction is controlled for, the differences in cesarean rates are much smaller or disappear entirely. Induction is the root of the problem, independent from obesity itself.

Additionally, several studies over the years have found that when induction is frequently used with obese women, it often is the starting point for other poor outcomes.

If you want to improve outcomes in obese women, start by addressing the high induction rate, especially in first-time mothers. 

A few researchers are beginning to get it. A recent American study found that first-time obese mothers induced at term had a much higher cesarean rate (40% vs. 25%) and a higher rate of neonatal admissions to the NICU than those obese women who were managed expectantly. They concluded:

Elective labor induction at term in obese nulliparous parturients carries an increased risk of cesarean delivery and higher neonatal intensive care unit admission rate as compared with expectant management.

A major Irish study recently recommended that inductions only be undertaken for strict indications in obese women:

Due to the short-term and long-term implications of an unsuccessful induction in an obese primigravida, we recommend that induction of labor should only be undertaken for strict obstetric indications after careful consideration by an experienced clinician.

One recent French review concluded:

It may be possible to reduce primary and thus repeat cesarean delivery rates among obese women by preventive actions targeting labor induction in primiparous women and prelabor cesarean deliveries in multiparous women.

Bottom line, care providers need to be much more cautious about the amount of interventions they employ in the pregnancies of higher weight women.

In particular, induction of labor should be avoided when not truly medically indicated, especially in first-time mothers. If it occurs, it should usually wait until a woman's Bishop Score indicates a ripe cervix, and more patience during labor should be employed before moving to a cesarean section. 

These changes, rather than browbeating women about weight loss interventions, will be the ones that bring about the biggest improvements in outcome for women of size.


References

BMC Pregnancy Childbirth. 2014 Dec 20;14(1):422. [Epub ahead of print] Pre-pregnancy Body Mass Index (BMI) and delivery outcomes in a Canadian population. Vinturache A, Moledina N, McDonald S, Slater D, Tough S. PMID: 25528667

...This study is a secondary analysis of the All Our Babies Cohort, a prospective, community-based pregnancy cohort in Calgary, Alberta...(n=1996)...Women with increased pre-pregnancy BMI were more likely to develop pregnancy complications such as preeclampsia (OR 3.5, CI 2.0-4.6 for overweight; OR 5.3, CI 3.3-8.5 for obese) and gestational diabetes (OR 3.0, CI 1.8-5.0 for overweight; OR 6.5, CI 3.7-11.2, for obese) than normal weight women. Spontaneous onset of labour was recorded in 71.2% of women with normal pre-pregnancy BMI, whereas 39.3% of overweight and 49% of obese women had their labour induced. For women with spontaneous labour, pre-pregnancy BMI was not a significant risk factor for mode of delivery, controlling for covariates. Among women with induced labor, obesity was a significant risk factor for delivery by C-section (adjusted OR 2.2; CI 1.2-4.1). CONCLUSIONS: Even among women with term, singleton pregnancies obtaining prenatal care in community-based settings, obese women who undergo labour induction are at increased risk of obstetrical interventions at delivery....

Am J Obstet Gynecol. 2014 Jul;211(1):53.e1-5. doi: 10.1016/j.ajog.2014.01.034. Epub 2014 Jan 31. Risk of cesarean in obese nulliparous women with unfavorable cervix: elective induction vs expectant management at term. Wolfe H1, Timofeev J2, Tefera E3, Desale S3, Driggers RW2. PMID: 24486226

OBJECTIVE: The objective of the study was to examine maternal and neonatal outcomes in obese nulliparous women with an unfavorable cervix undergoing elective induction of labor compared with expectant management after 39.0 weeks. STUDY DESIGN: This was a retrospective analysis of a cohort of nulliparous women with a vertex singleton gestation who delivered at MedStar Washington Hospital Center from 2007 to 2012. Patients with unfavorable cervix between 38.0 and 38.9 weeks (modified Bishop <5) and a body mass index of 30.0 kg/m(2) or greater at the time of delivery were included. Women undergoing elective induction between 39.0 and 40.9 weeks' gestation were compared with those who were expectantly managed beyond 39.0 weeks...RESULTS: Sixty patients meeting inclusion criteria underwent elective induction of labor and were compared with 410 patients expectantly managed beyond 39.0 weeks. The rate of cesarean delivery was significantly higher in the electively induced group (40.0% vs 25.9%, respectively, P = .022)...The neonatal intensive care unit admission rate was higher in the electively induced group (18.3% vs 6.3%, P = .001)...CONCLUSION: Elective labor induction at term in obese nulliparous parturients carries an increased risk of cesarean delivery and higher neonatal intensive care unit admission rate as compared with expectant management.

Am J Obstet Gynecol. 2015 Feb;212(2):241.e1-9. doi: 10.1016/j.ajog.2014.08.002. Epub 2014 Aug 6. The risk of prelabor and intrapartum cesarean delivery among overweight and obese women: possible preventive actions. Hermann M1, Le Ray C2, Blondel B3, Goffinet F2, Zeitlin J3. PMID: 25108139

...We modeled relative risks (RRs) and risk differences of prelabor and intrapartum cesarean delivery by prepregnancy body mass index (obese, ≥30 kg/m(2); overweight, 25-29.9 kg/m(2); normal weight, 18.5-24.9 kg/m(2)) in a nationally representative sample of 12,297 French women. Models were stratified by parity and previous cesarean status. Covariates included maternal sociodemographic characteristics, medical conditions, pregnancy complications, and induction of labor. RESULTS:...Increased intrapartum cesarean delivery risks for primiparous women were related to more frequent labor induction (42.6% vs 23.8% for normal-weight women). CONCLUSION: It may be possible to reduce primary and thus repeat cesarean delivery rates among obese women by preventive actions targeting labor induction in primiparous women and prelabor cesarean deliveries in multiparous women. Further research is needed on the impact of limiting inductions on cesarean delivery risks for obese primiparous women.

Acta Obstet Gynecol Scand. 2013 Dec;92(12):1414-8. doi: 10.1111/aogs.12263. Maternal obesity and induction of labor. O'Dwyer V1, O'Kelly S, Monaghan B, Rowan A, Farah N, Turner MJ. PMID: 24116732

...Compared with women with a normal BMI, obese primigravidas but not obese multigravidas were more likely to have labor induced. In primigravidas who had labor induced, the cesarean section rate was 20.6% (91/442) compared with 8.3% (17/206) in multigravidas who had labor induced (p < 0.001). In obese primigravidas, induction of labor was also more likely to be associated with other interventions such as epidural analgesia, fetal blood sampling and emergency cesarean section. In contrast, induction of labor in obese multigravidas was not only less common but also not associated with an increase in other interventions compared with multigravidas with a normal BMI. CONCLUSIONS: Due to the short-term and long-term implications of an unsuccessful induction in an obese primigravida, we recommend that induction of labor should only be undertaken for strict obstetric indications after careful consideration by an experienced clinician.

J Midwifery Womens Health. 2014 Jan-Feb;59(1):43-53. doi: 10.1111/jmwh.12073. Epub 2014 Jan 8. Intrapartum management associated with obesity in nulliparous women. Carlson NS, Lowe NK. PMID: 24400789

...Intrapartum interventions used significantly more often for healthy, obese nulliparous women when compared with normal-weight women were induction of labor, augmentation of labor, and cesarean birth. It is unclear if assisted vaginal birth occurs more frequently among obese women. Epidural anesthesia, artificial rupture of membranes prior to 6 cm of cervical dilation, and early hospital admission were shown in separate studies to be used more often in obese women. Intrapartum interventions were used more frequently in obese women in a dose-dependent manner by body mass index...Implications for clinical practice from this systematic review are that healthy, nulliparous obese women are exposed to common intrapartum interventions more often than normal-weight women. In the absence of evidence on the use of appropriate use of intrapartum interventions in this population, health care providers should carefully monitor management choices when working with healthy, nulliparous obese women.

BJOG. 2005 Jun;112(6):768-72. Outcome of pregnancy in a woman with an increased body mass index. Usha Kiran TS1, Hemmadi S, Bethel J, Evans J. PMID: 15924535

...The study sample was drawn from the Cardiff Births Survey, a population-based database comprising of a total of 60,167 deliveries in the South Glamorgan area between 1990 and 1999...RESULTS: We report an increased risk [quoted as odds ratio (OR) and confidence intervals CI)] of postdates, 1.4 (1.2-1.7); induction of labour, 1.6 (1.3-1.9); caesarean section, 1.6 (1.4-2); macrosomia, 2.1 (1.6-2.6); shoulder dystocia, 2.9 (1.4-5.8); failed instrumental delivery, 1.75 (1.1-2.9); increased maternal complications such as blood loss of more than 500 mL, 1.5 (1.2-1.8); urinary tract infections, 1.9 (1.1-3.4); and increased neonatal admissions with complications such as neonatal trauma, feeding difficulties and incubator requirement. CONCLUSION: Obese women appear to be at risk of intrapartum and postpartum complications. Induction of labour appears to be the starting point in the cascade of events....

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...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 less than 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.

Aust N Z J Obstet Gynaecol. 2011 Apr;51(2):172-4. Impact of morbid obesity on the mode of delivery and obstetric outcome in nulliparous singleton pregnancy and the implications for rural maternity services. Green C, Shaker D. PMID: 21466521

...We conclude that morbid obesity is associated with a significantly higher risk of pre-existing medical conditions, developing antenatal complications, induction of labour, caesarean section and greater birth weight. However, there was no significant difference in caesarean section rates when adjusted for induction of labour....

Induction or Waiting in Obese First-Time Mothers?

This is a follow-up post about a study reported on briefly here earlier this year.

It is about the question of whether "obese" women should have their labors induced proactively at term or be expectantly managed, and whether elective induction increases their risk for cesarean and other poor outcomes (like fetal distress, more Neonatal Intensive Care Unit utilization, etc.).

Induction of Labor: Help or Harm?

Induction of labor is an increasingly common intervention in women of all sizes. The question is whether it does more harm than good.

Much research shows it is associated with an increased risk for cesarean, but other research does not always show this. A definitive answer still eludes us on whether/when induction is appropriate.

Complicating this question is the whether or not the mother's cervix is ripe. Inducing on a very ripe cervix is much less likely to lead to a cesarean than inducing on an unripe cervix (Bishop Score less than 5-7, or cervical dilation more than 3 or 4).  And this is especially true in first-time mothers (nulliparous women).

An increased maternal BMI complicates this debate because of a perceived heightening of risk. One of the biggest dilemmas facing maternity care providers who are caring for "obese" women is how to manage them at term. Should they electively induce labor at 39 or 40 weeks, or should they wait for labor to start on its own if no complications occur?

Many care providers these days seem to be electively inducing obese women at 39 or 40 weeks, sometimes regardless of cervical ripeness (when they are not trying to talk them into a planned cesarean).

Many have the best intentions with this; they think inducing a smaller baby will lessen the risk for cesarean or shoulder dystocia, or they think that baby will have better outcomes if they induce before complications might develop. But do these assumptions hold up under scrutiny?

The problem is that little research has actually examined the question of whether it is beneficial to routinely induce obese mothers without specific medical indications for induction.

Care providers usually go ahead and do so, assuming that inducing obese women at term is beneficial, but there has been little direct evidence one way or the other in a study specifically designed to look at the benefits and risks of routine elective induction in high-BMI women.

Sadly, there is still no large study that rigorously examines this question.

However, we now have a small study that begins to address it. The study looks at the outcomes of elective induction or expectant management of obese first-time mothers with an unripe cervix.

The Study

This retrospective study was conducted by doctors at a hospital in Washington D.C. They studied obese (BMI 30 or more) first-time mothers with no chronic medical co-morbidities (like chronic hypertension, pre-existing diabetes, etc.). Women were admitted to the study between 39 and 41 weeks, and only if they had an unripe cervix (Bishop score less than 5) that was documented during week 38.

The researchers compared the results of electively inducing obese first-time mothers with an unripe cervix (n=60) at 39-41 weeks with expectant management (waiting for spontaneous labor or inducing only if medical indications arose, n=410). Age, BMI at delivery, and prenatal weight gain were similar between groups.

It's important to note that the authors did not compare elective induction to only spontaneous labor. They compared elective induction to expectant management, many of whom eventually were induced if medical indications for induction of labor arose.

The results of this study would probably be even more striking if they compared elective induction only to spontaneous labor, but the authors felt that this was not an appropriate comparison, stating,
"Because spontaneous labor is not something a provider can choose for a patient, it is not realistic to use this as a comparison control group; it is more appropriate to compare the induction of labor to expectant management."

Even so, the bottom line was that the researchers found that electively inducing labor in high-BMI first-time mothers with an unripe cervix raised the risk for cesarean. By quite a bit.

The cesarean rate was 25.9% in the obese women in the expectant management group, and the cesarean rate was 40% in the elective induction group.

That's a significant increase in risk for cesarean.

Only 10.7% of women in the expectant management group were still pregnant by 41 weeks; all the others had either gone into labor spontaneously (36.8%) or had been induced for commonly-accepted medical indications (rupture of membranes, gestational hypertension, non-reassuring fetal heart rate tracings, etc.). So quite a few of the expectant management group were eventually induced, yet the difference in the cesarean rate was still quite marked.

Another important finding was that the elective induction group had three times the rate of admission to the Neonatal Intensive Care Unit (NICU) after the birth (18.3% vs. 6.3%).

This suggests that instead of reducing harm to the baby (as many care providers believe), elective induction in this population may actually increase the risks of poor outcomes.

Now, of course the study had a relatively small sample size, especially in the electively induced group. It was also a retrospective study. So the authors point out that further research on this topic is needed, preferably with a large prospective study.

Still, even with the study's weaknesses, it suggests strong caution towards elective induction in obese women with an unripe cervix. As the authors note:

In a joint summary from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the Society for Maternal-Fetal Medicine, and the American College of Obstetricians and Gynecologists, physicians are urged to perform labor induction primarily for a medical indication and if done for nonmedical indications...to ensure that the 'cervix should be favorable, especially in the nulliparous patient.' Our findings support this assertion.

Other studies 

This study echoes a number of studies which have found higher c-section rates and complications in obese women who were induced (especially first-time obese mothers).

Of course, these studies did not specifically examine the question of whether routine induction in obese women improved overall outcomes. Still, their findings seem to also suggest caution around the idea of routine induction in obese women.

Although a higher rate of complications like pre-eclampsia means that some obese women will be induced for true medical indications, many others are induced for more dubious indications, based on questionable beliefs. These must be examined carefully.

For example, many providers believe that inducing early when the baby is smaller will lessen the risk for cesarean. Yet a number of studies have shown that it actually increases the risk for cesarean.

The combination of a suspected big baby and a high-BMI mother is a particularly potent combination that leads to many cesareans. A 2006 Massachusetts study found that the combination of induction, a suspected big baby, and first-time mother doubled the cesarean rate in the high-BMI women studied.

Many women of size are induced labor at term ostensibly to prevent a shoulder dystocia. Yet a recent New York study found that induction of labor actually increased the risk for shoulder dystocia (2.85x the risk), and especially so in obese women (5.64x the risk). By inducing women of size, providers may often be creating the very situation they are trying to avoid.

Other care providers induce because they believe it will improve outcomes in high-BMI women. A 2005 Welsh study on obese women with no complications found that the cesarean rate was 19% in the group with spontaneous labor and 41% in the induced group. Like in the present study, the Welsh study noted that the induction of labor was the start of many problems for the obese women in the group, including more blood loss, more UTIs, more babies in the NICU, more feeding difficulties, more neonatal trauma, etc.

So while many care providers think they are doing obese women a favor by inducing them proactively at term, there is strong reason to suspect that they may actually be doing more harm than good.

So much so that a 2013 Irish study (which found higher rates of emergency cesarean in induced obese first-time mothers) concluded:

Due to the short-term and long-term implications of an unsuccessful induction in an obese primigravida, we recommend that induction of labor should only be undertaken for strict obstetric indications after careful consideration by an experienced clinician.

Conclusion

Research is clear that induction of labor is an extremely common intervention in obese women.

These and other studies suggest that perhaps a little more time and patience is needed at the end of pregnancy in obese women, and that induction should only be undertaken for strict medical indications.

Furthermore, it is time that larger studies directly address the question of whether routine induction at term improves or harms outcomes in obese women and their babies.

These potential studies should particularly look at outcomes among subsets of high-BMI populations, including obese women with complications and those without, those with differing levels of obesity, obese first-time mothers with an unripe cervix, obese multips with a prior vaginal birth, obese women where a big baby is suspected, etc.

Only then will care providers receive clearer guidance on the best management of women of size at term in many of the scenarios they are likely to encounter. It's FAR past time for such targeted research to occur.

We need care based on real evidence, not simply on assumptions about what's best for obese women.


References

Am J Obstet Gynecol. 2014 Jul;211(1):53.e1-5. doi: 10.1016/j.ajog.2014.01.034. Epub 2014 Jan 31. Risk of cesarean in obese nulliparous women with unfavorable cervix: elective induction vs expectant management at term. Wolfe H1, Timofeev J2, Tefera E3, Desale S3, Driggers RW2. PMID: 24486226

OBJECTIVE: The objective of the study was to examine maternal and neonatal outcomes in obese nulliparous women with an unfavorable cervix undergoing elective induction of labor compared with expectant management after 39.0 weeks. STUDY DESIGN: This was a retrospective analysis of a cohort of nulliparous women with a vertex singleton gestation who delivered at MedStar Washington Hospital Center from 2007 to 2012. Patients with unfavorable cervix between 38.0 and 38.9 weeks (modified Bishop <5) and a body mass index of 30.0 kg/m(2) or greater at the time of delivery were included. Women undergoing elective induction between 39.0 and 40.9 weeks' gestation were compared with those who were expectantly managed beyond 39.0 weeks...RESULTS: Sixty patients meeting inclusion criteria underwent elective induction of labor and were compared with 410 patients expectantly managed beyond 39.0 weeks. The rate of cesarean delivery was significantly higher in the electively induced group (40.0% vs 25.9%, respectively, P = .022). Other maternal outcomes, including operative vaginal delivery, rate of third- or fourth-degree lacerations, chorioamnionitis, postpartum hemorrhage, and a need for a blood transfusion were similar. The neonatal intensive care unit admission rate was higher in the electively induced group (18.3% vs 6.3%, P = .001). Birthweight, umbilical artery pH less than 7.0, and Apgar less than 7 at 5 minutes were similar. CONCLUSION: Elective labor induction at term in obese nulliparous parturients carries an increased risk of cesarean delivery and higher neonatal intensive care unit admission rate as compared with expectant management.

Acta Obstet Gynecol Scand. 2013 Dec;92(12):1414-8. doi: 10.1111/aogs.12263. Maternal obesity and induction of labor. O'Dwyer V1, O'Kelly S, Monaghan B, Rowan A, Farah N, Turner MJ. PMID: 24116732

...Of 2000 women enrolled, 50.4% (n = 1008) were primigravidas and 17.3% (n = 346) were obese. The induction rate was 25.6% and the overall cesarean section rate 22.0%. Primigravidas were more likely to have labor induced than multigravidas (38.1% vs. 23.4%, p < 0.001). Compared with women with a normal BMI, obese primigravidas but not obese multigravidas were more likely to have labor induced. In primigravidas who had labor induced, the cesarean section rate was 20.6% (91/442) compared with 8.3% (17/206) in multigravidas who had labor induced (p < 0.001). In obese primigravidas, induction of labor was also more likely to be associated with other interventions such as epidural analgesia, fetal blood sampling and emergency cesarean section. In contrast, induction of labor in obese multigravidas was not only less common but also not associated with an increase in other interventions compared with multigravidas with a normal BMI. CONCLUSIONS: Due to the short-term and long-term implications of an unsuccessful induction in an obese primigravida, we recommend that induction of labor should only be undertaken for strict obstetric indications after careful consideration by an experienced clinician.

BJOG. 2005 Jun;112(6):768-72. Outcome of pregnancy in a woman with an increased body mass index. Usha Kiran TS1, Hemmadi S, Bethel J, Evans J. PMID: 15924535

...The study sample was drawn from the Cardiff Births Survey, a population-based database comprising of a total of 60,167 deliveries in the South Glamorgan area between 1990 and 1999. POPULATION: Primigravid women with a singleton uncomplicated pregnancy with cephalic presentation of 37 or more weeks of gestation... METHODS: Comparisons were made between women with a body mass index of 20-30 and those with more than 30...RESULTS: We report an increased risk [quoted as odds ratio (OR) and confidence intervals CI)] of postdates, 1.4 (1.2-1.7); induction of labour, 1.6 (1.3-1.9); caesarean section, 1.6 (1.4-2); macrosomia, 2.1 (1.6-2.6); shoulder dystocia, 2.9 (1.4-5.8); failed instrumental delivery, 1.75 (1.1-2.9); increased maternal complications such as blood loss of more than 500 mL, 1.5 (1.2-1.8); urinary tract infections, 1.9 (1.1-3.4); and increased neonatal admissions with complications such as neonatal trauma, feeding difficulties and incubator requirement. CONCLUSION: Obese women appear to be at risk of intrapartum and postpartum complications. Induction of labour appears to be the starting point in the cascade of events....

J Midwifery Womens Health. 2006 Jul-Aug;51(4):254-9. Maternal body mass index, delivery route, and induction of labor in a midwifery caseload. Graves BW1, DeJoy SA, Heath A, Pekow P. PMID: 16814219

...This retrospective cohort study examined the outcomes of 1500 consecutively delivered women who were cared for by two midwifery practices and delivered between January 1, 1998, and December 31, 2000. Cesarean delivery was significantly associated with the obese BMI (P < .001), nulliparity (P < .02), and newborn birth weight (P =.006). Prenatal weight gain did not have a significant correlation with cesarean birth (P = .24). In multivariable modeling, obese BMI, high newborn birth weight, nulliparity, and induction of labor increased the risk of cesarean birth. There was also a significant association between higher BMI and risk of induction of labor (P < .001). In a secondary analysis, obese BMI was associated with increased risk of induction in cases with ruptured membranes (OR 2.2; 95% CI 1.4-3.4) and postdates pregnancy (OR 2.0; 95% CI 1.1-3.4).

Obstet Gynecol. 2014 May;123 Suppl 1:172S. doi: 10.1097/01.AOG.0000447182.21511.09. Shoulder dystocia and labor induction stratified by maternal weight: to induce or not to induce? Sirota I1, Francis A, Chevalier M, Ashmead G. PMID: 24770084

...Retrospective study of all shoulder dystocia patients who delivered from 1998 to 2010, women in a control group without shoulder dystocia were matched two to one by maternal BMI, age, parity, and diabetic status...RESULTS: Included in the study was 57,259 deliveries; 144 shoulder dystocia cases and 288 women in the control group met study criteria. One hundred seven (74%) shoulder dystocia cases were induced or augmented; 37 (26%) labored spontaneously. One hundred thirty-six (47%) women in the control group were induced or augmented; 152 (53%) labored spontaneously... Across all BMIs, induced patients were 2.85 times more likely to have shoulder dystocia than noninduced patients (95% confidence interval 1.57-6.14; P<.001). After stratifying by BMI, induced normal-weight patients were 2.11 times more likely to have shoulder dystocia than spontaneously laboring normal-weight patients; induced or augmented overweight patients were 4.74 times more likely to have shoulder dystocia than their spontaneously laboring counterparts; and induced or augmented obese patients were 5.64 times more likely to have shoulder dystocia than their noninduced cohorts...CONCLUSION: Induction or augmentation appears to be associated with an increased shoulder dystocia risk with increasing maternal BMI.

Arch Dis Child Fetal Neonatal Ed. 2014 Jun;99 Suppl 1:A114-5. doi: 10.1136/archdischild-2014-306576.330. PLD.30 A 5-year review of maternal obesity and induction of labour on mode of delivery and risk of labour, anaesthetic and neonatal complications. Joannides C, Hon M, McGlone P, Parasuraman R, Al-Rawi S. PMID: 25020968

...Retrospective analysis of women with a booking BMI >45 between January 2009 and October 2013...RESULTS: 158 patients were analysed (mean BMI 49). 68% of all patients were either induced or required labour augmentation (background rate of 39%). 64% of these women achieved a vaginal delivery, increasing to 70% if no induction or augmentation. 71% of multiparous women who spontaneously laboured and had previously achieved a vaginal delivery, delivered vaginally again. Half of primiparous women requiring induction or labour augmentation had an emergency caesarean. 49% had intrapartum regional anaesthetic. 42% required multiple attempts, 19% needed an epidural re-site or spinal for theatre. CONCLUSION: These results mirror the UKOSS study findings. Higher maternal BMI is associated with an increased incidence of induction and augmentation of labour. Despite this the vaginal delivery rate is high. Primiparous women requiring induction or augmentation of labour were most susceptible to obstetric intervention....

Wait for Spontaneous Labor If the Cervix Isn't Ripe

Here is a new study that suggests that it may be better to await spontaneous labor in first-time obese mothers with an unripe cervix, rather than trying to force labor to start regardless of the Bishop's Score.

Reference

Am J Obstet Gynecol. 2014 Jan 31. pii: S0002-9378(14)00063-5. doi: 10.1016/j.ajog.2014.01.034. [Epub ahead of print] Risk of cesarean in obese nulliparous women with unfavorable cervix: elective induction vs expectant management at term. Wolfe H1, Timofeev J2, Tefera E3, Desale S3, Driggers RW2. PMID: 24486226

OBJECTIVE: The objective of the study was to examine maternal and neonatal outcomes in obese nulliparous women with an unfavorable cervix undergoing elective induction of labor compared with expectant management after 39.0 weeks. STUDY DESIGN: This was a retrospective analysis of a cohort of nulliparous women with a vertex singleton gestation who delivered at MedStar Washington Hospital Center from 2007 to 2012. Patients with unfavorable cervix between 38.0 and 38.9 weeks (modified Bishop <5) and a body mass index of 30.0 kg/m2 or greater at the time of delivery were included. Women undergoing elective induction between 39.0 and 40.9 weeks' gestation were compared with those who were expectantly managed beyond 39.0 weeks. Outcomes were analyzed using χ2, Student t, or Wilcoxon rank sum tests as appropriate with a significance set at P < .05. RESULTS: Sixty patients meeting inclusion criteria underwent elective induction of labor and were compared with 410 patients expectantly managed beyond 39.0 weeks. The rate of cesarean delivery was significantly higher in the electively induced group (40.0% vs 25.9%, respectively, P = .022). Other maternal outcomes, including operative vaginal delivery, rate of third- or fourth-degree lacerations, chorioamnionitis, postpartum hemorrhage, and a need for a blood transfusion were similar. The neonatal intensive care unit admission rate was higher in the electively induced group (18.3% vs 6.3%, P = .001). Birthweight, umbilical artery pH less than 7.0, and Apgar less than 7 at 5 minutes were similar. CONCLUSION: Elective labor induction at term in obese nulliparous parturients carries an increased risk of cesarean delivery and higher neonatal intensive care unit admission rate as compared with expectant management.

High Induction Rates and High Cesarean Rates in Women of Size

In honor of Cesarean Awareness Month, let's dissect yet another blame-the-fat-mother study.

In this study, the authors looked at the rate of complications and interventions by class of "obesity." As they expected, they found that the rate of complications rose as the mother's BMI rose.  They also found that the rate of interventions like inductions and c-sections rose as the mother's BMI rose, and emphasized the importance of weight loss to prevent these.

Gah!

These studies always blame the fat woman and emphasize weight loss to prevent cesareans etc., instead of also examining how their own biases and practices (a high induction rate in obese women and a low surgical threshold) are negatively impacting outcomes in women of size.  

In this study, induction rates increased from 25.3% in "normal" BMI women to 42.9% in class III obesity women.  

Where's the questioning of the necessity of most of these inductions?  

Sure, inductions to some extent are going to be increased because there is more blood sugar and blood pressure issues in obese women, and it's true that these tend to rise as BMI rises. So by all means, go ahead and emphasize the importance of good nutrition and regular exercise as a possible way to decrease the number of obese women with complications. No one objects to that, as long as the emphasis is on reasonable expectations and not extreme measures.

But nearly half of the obese women in this study "needing" to be induced?  I don't think so.  Many of these inductions are NOT due to medical indications like high blood pressure or uncontrolled blood sugar.  Many are because docs are nervous about a big baby and decide to induce early (even though that increases the cesarean rate substantially and does not reduce shoulder dystocia), or because they think that pregnant fat women will never go into labor on their own.  Bzzzt on both counts!

Researchers always assume in studies that every induction in an obese woman is a necessary induction.  Some indeed are, but many are NOT.  Yet most researchers steadfastly refuse to connect the dots between the insanely high induction rate in fat women and the obscenely high cesarean rate in this group.  Augh!

Researchers, if you really want to start lowering the cesarean rate in women of size, start examining the insanely high induction rate of these women, and start putting those inductions under the microscope to see which ones are truly justified and which ones are not.  

Cutting back on the rate of questionable inductions in "obese" women has tremendous potential for lowering the cesarean rate in this group, and, given the high failure rate of most diets, is much more achievable than pressuring all fat women to lose weight before pregnancy.  

Reference

J Obstet Gynaecol Can. 2013 Mar;35(3):224-33. The impact of increasing obesity class on obstetrical outcomes. El-Chaar D, Finkelstein SA, Tu X, Fell DB, Gaudet L, Sylvain J, Tawagi G, Wen SW, Walker M.  PMID: 23470110

Objective: Nationally, rates of obesity continue to rise, resulting in increased health concerns for women of reproductive age. Identifying the impact of maternal obesity on obstetrical outcomes is important to enhance patient care. 

Methods: We conducted a retrospective cohort study of 6674 women who delivered a singleton infant at ≥ 20 weeks' gestation between December 1, 2007, and March 31, 2010, at The Ottawa Hospital. Maternal pre-pregnancy BMI was used to classify women into normal, overweight, and obese (class I/II/III) categories according to WHO classifications. Obstetrical outcomes among obese women were compared with those of women with normal BMI. Multivariable regression models were used to determine adjusted odds ratios and 95% confidence intervals. 

Results: Compared with women with normal BMI, obese women had significantly higher rates of preeclampsia, gestational hypertension, and gestational diabetes, and these rates increased with increasing BMI (trend-test P < 0.001). There was a significant increase in rates of induction of labour in the obesity categories, from 25.3% in women with normal BMI to 42.9% in women with class III morbid obesity (aOR 1.67; 95% CI 1.43 to 1.93). Rates of primary Caesarean section rose with increasing BMI and were highest in women with class III morbid obesity (36.2% vs. 22.1% in women with normal BMI) (aOR 1.46; 95% CI 1.23 to 1.73). 

Conclusion: Increasing BMI is associated with increasing rates of preeclampsia, gestational hypertension, and gestational diabetes. There is a significant increase in rates of induction of labour with increasing obesity class, and a significantly increased Caesarean section rate with higher BMI. Obstetrical care providers should counsel obese patients about the risks they face and the importance of weight loss before pregnancy.