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.

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.

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....