Saturday, January 12, 2019

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.


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.

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