Note: When I refer to a spontaneous labor, I mean a non-induced/augmented labor. Also, given that the risk of rupture increases with induction, a hospital is the best location for an induction.
Many of the comments left at the Forced Cesarean mom story questioned the safety of inducing a VBAC mom. Many people believe that is it excessively dangerous and that VBACs should never been induced or augmented. This is just not the case.
Spontaneous labor is always preferable to induced or augmented labor but there are medical conditions that can necessitate the immediate birth of a baby. It’s nice for those women for whom vaginal birth is still an option to have a choice: gentle induction/ augmentation or repeat cesarean. Of course, reviewing the risks and benefits of available options, including doing nothing, is essential. Some women might be more comfortable scheduling a cesarean whereas others might want to give a gentle Pitocin and/or Foley catheter induction a go.
ACOG’s stance on inducing VBACs
The latest 2010 VBAC Practice Bulletin No. 115 produced by the American Congress of Obstetricians & Gynecologists (ACOG) asserts:
Induction of labor for maternal or fetal indications remains an option in women undergoing TOLAC [trial of labor after cesarean]… However, the potential increased risk of uterine rupture associated with any induction, and the potential decreased possibility of achieving VBAC, should be discussed… Misoprostol [Cytotec] should not be used for third trimester cervical ripening or labor induction in patients who have had a cesarean delivery or major uterine surgery.
Stuart Fischbein MD, a vaginal breech/twins and VBAC supportive Southern California OB, recently shared this on my Facebook page,
According to ACOG, prior low transverse c/section is not a contraindication to induction (other than the use of Misoprostol [Cytotec]) so a Foley balloon or Pitocin may be used safely in these women. The problem arises when a practitioner does not believe in doing inductions on women with prior c/section. Despite the evidence and the ACOG clinical guideline the reality is that many doctors will just not want to deal with it.
“Many doctors will just not want to deal with it” for a variety of reasons including experiencing a recent uterine rupture or lawsuit and pressure from hospital administrators or other OBs in their practice. It’s good to know from the beginning if your care provider is open to a gentle VBAC induction and under what conditions they would recommend induction. (See below for the Mayo Clinic’s reasons for induction.) This is why I suggest asking care providers when you first meet with them: “Under what circumstances would you induce a VBAC?” and “What induction methods do you use?”
Medical reasons for induction
While many women are induced for non-medical reasons, such as being pregnant for 40 weeks and one day, there are many medical conditions where induction is a reasonable option. According to the Mayo Clinic’s article Inducing labor: when to wait, when to induce dated July 23, 2011:
Your health care provider might recommend inducing labor for various reasons, primarily when there’s concern for your health or your baby’s health. For example:
- You’re approaching two weeks beyond your due date, and labor hasn’t started naturally
- Your water has broken, but you’re not having contractions
- There’s an infection in your uterus
- Your baby has stopped growing at the expected pace
- There’s not enough amniotic fluid surrounding the baby (oligohydramnios)
- Your placenta has begun to deteriorate
- The placenta peels away from the inner wall of the uterus before delivery — either partially or completely (placental abruption)
- You have a medical condition that might put you or your baby at risk, such as high blood pressure or diabetes
ACOG’s 2009 recommendations on induction lists the following reasons:
- Abruptio placentae [placental abruption]
- Chorioamnionitis [infection in your uterus]
- Fetal demise [baby has passed away]
- Gestational hypertension
- Preeclampsia, eclampsia
- Premature rupture of membranes
- Postterm pregnancy [after 42 weeks]
- Maternal medical conditions (eg, diabetes, mellitus, renal [kidney] disease, chronic pulmonary disease, chronic hypertension, antiphospholipid syndrome)
- Fetal compromise (eg, severe fetal growth restriction, isoimmunization, oligohydramnios)
Big babies & going overdue
ACOG’s latest VBAC Pratice Bulletin No. 115 states that going over 40 weeks or suspecting a “big baby” should not prevent a woman from planning a VBAC. I suggest asking your care provider at your first appointment about what they would recommend doing if you go past 40 weeks, past 42 weeks, or if they believe your baby is large. They may suggest a cesarean, a gentle induction, or they be open to waiting for spontaneous labor. Then you decide how you feel about their answer. If you decide that their answer is not a good fit for you, you can weigh that against the responses of other VBAC supportive care providers in your area.
Uterine rupture rates in induced/augmented labors
There are two primary factors when looking at uterine rupture during an induction: the drug and the dose. Keep in mind that while the risk of rupture generally increases as the dosage increases, two women can respond very differently to the same dose of the same drug. According to JHP Pharmaceuticals, LLC, the manufacturer of Pitocin,
Oxytocin has specific receptors in the myometrium and the receptor concentration increases greatly during pregnancy, reaching a maximum in early labor at term. The response to a given dose of oxytocin is very individualized and depends on the sensitivity of the uterus, which is determined by the oxytocin receptor concentration.
Additionally, they assert that Pitocin should not be used for induction without medical indication:
Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, Pitocin is not indicated for elective induction of labor.
Many women point to the fact that the Pitocin drug insert states, “Except in unusual circumstances, oxytocin should not be administered in the following conditions” and then lists “previous major surgery on the cervix or uterus including cesarean section.” However, a prior cesarean is not listed under contraindications and the drug insert is clear:
The decision [to use Pitocin in a woman with a prior cesarean] can be made only by carefully weighing the potential benefits which oxytocin can provide in a given case against rare but definite potential for the drug to produce hypertonicity or tetanic spasm.
The elevated risk of rupture due to induction has been documented in several studies. Landon (2004) found that spontaneous labors had a 0.4% rate of rupture. That increased 2.5 times for induced labors (1.0%) and 2.25 times for augmented labors (0.9%).
Landon further broke out rupture rates by type of induction:
- 1.4% (N = 13) with any prostaglandins (with or without oxytocin)
- 0% with prostaglandins alone
- 0.9% (n = 15) with no prostaglandins (includes mechanical dilation with a foley catheter with or without oxytocin), and
- 1.1% (N = 20) with oxytocin alone.
Overall, they found 0.7% of women experienced an uterine rupture with an additional 0.7% experiencing a dehiscence.
Landon (2004) did a great job in providing rates of rupture per drug, but we don’t know the dose used in the induced/ augmented labors that ruptured versus those that didn’t rupture.
ACOG quotes a couple studies in their 2010 VBAC Practice Bulletin (emphasis mine):
One study of 20,095 women who had undergone prior cesarean delivery (81) found a rate of uterine rupture of 0.52% for spontaneous labor, 0.77% for labor induced without prostaglandins, and 2.24% for prostaglandin induced labor. This study was limited by reliance on the International Classification of Diseases, 9th Revision coding for diagnosis of uterine rupture and the inability to determine whether prostaglandin use itself or the context of its use (eg, unfavorable cervix, need for multiple induction agents) was associated with uterine rupture.
In a multicenter study of 33,699 women undergoing TOLAC, augmentation or induction of labor also was associated with an increased risk of uterine rupture compared with spontaneous labor (0.4 % for spontaneous labor, 0.9% for augmented labor, 1.1% for oxytocin alone, and 1.4% for induction with prostaglandins with or without oxytocin) (4). A secondary analysis of 11,778 women from this study with one prior low transverse cesarean delivery showed an increase in uterine rupture only in women undergoing induction who had no prior vaginal delivery (1.5% versus 0.8%, P=.02). Additionally, uterine rupture was no more likely to occur when labor induction was initiated with an unfavorable cervix than with a favorable cervix (91). Another secondary analysis examined the association between maximum oxytocin dose and the risk of uterine rupture (94). They noted a dose response effect with increasing risk of uterine rupture with higher maximum doses of oxytocin. Because studies have not identified a clear threshold for rupture, an upper limit for oxytocin dosing with TOLAC has not been established.
Induced labor is less likely to result in VBAC than spontaneous labor (44, 47, 92, 99). There is some evidence that this is the case regardless of whether the cervix is favorable or unfavorable, although an unfavorable cervix decreases the chance of success to the greatest extent (91, 100, 101). These factors may affect patient and health care provider decisions as they consider the risks and benefits of TOLAC associated with labor induction.
Given the lack of compelling data suggesting increased risk with mechanical dilation and transcervical catheters, such interventions may be an option for TOLAC candidates with an unfavorable cervix.
The Guise 2010 Evidence Report is another excellent resource that reviewed VBAC research published to date. It talks extensively about uterine rupture in induced births on pages 58 – 69 and concluded (emphasis mine):
The strength of evidence on the risk of uterine rupture with pharmacologic IOL [induction of labor] methods was low due to lack of precision in estimates and inconsistency in findings. The overall risk of rupture with any IOL method at term was 1.5 percent [1 in 67] and 1.0 percent [1 in 100] when any GA [gestational age] is considered. Among women with GA greater than 40 weeks, the rate was highest at 3.2 percent [1 in 31]. Evaluation of the evidence on specific methods of IOL reveal that the lowest rate occurs with oxytocin [Pitocin] at 1.1 percent [1 in 91], then PGE2 [prostaglandin E2] at 2 percent [1 in 50], and the highest rate with misoprostol [Cytotec] at 6 percent [1 in 17]. These findings should be interpreted with caution as there was imprecision and inconsistency in the results among these studies. The risk of uterine rupture with mechanical methods of IOL is understudied. Other harms were inadequately reported to make conclusions. Relative to women with spontaneous labor, there was no increase in risk of rupture among those induced at term. However, the available evidence on women with induced labor after 40 weeks GA indicates an increased risk compared with spontaneous labor (risk difference 1.8 percent; 95 percent CI: 0.1 to 3.5 percent). The NNH [number needed to harm] in this group is 56 (for every 56 women greater than 40 weeks GA with IOL during a TOL [trial of labor], one additional rupture will occur compared with having spontaneous labor).
So the bottom line is: more large, good quality studies that control for induction are needed.
What is too risky?
As ACOG (2010) states in their latest Practice Bulletin:
Respect for patient autonomy supports the concept that patients should be allowed to accept increased levels of risk, however, patients should be clearly informed of such potential increase in risk and management alternatives.
I agree and believe that each individual woman has the right to informed consent and, together with her care provider, can make the best decision for her individual situation. I think it’s hard to argue that women seeking VBA2C, home birth, or unassisted birth should have the right to accept the elevated levels of risk that come with those decisions and yet say that the elevated risk that comes with induced VBACs is unacceptable.
Keep in mind that while the risk of rupture is higher in an induced VBAC, the risk is similar to the risk of rupture in a VBA2C (0.9% per Landon 2006). So it’s hard for one to support VBA2C and yet demonize a VBA1C induced for medical indication by saying the risk of rupture is to high.
It is also important to note that 90 out of 91 Pitocin induced TOLACs do not rupture (Landon, 2004 & Guise, 2010). So while the risk is generally higher in induced/ augmented labors, the overall risk is still low and occurs at a rate comparable to other obstetrical emergencies.
Myth: Most ruptures occur in induced/augmented labors
It’s imperative that women seeking VBAC understand that the single factor that increases their risk of uterine rupture the most is their prior cesarean section. And while having your labor induced/augmented does increase your risk of rupture, please do not believe the myth that a spontaneous labor provides complete protection from uterine rupture.
To disprove this myth, I direct you to “the largest prospective report of uterine rupture in women without a previous cesarean in a Western country” which found that most ruptures occur in spontaneous labors (Zwart, 2009). Zwart differentiated between uterine rupture and dehiscence and found (emphasis mine):
of the 208 scarred and unscarred uterine ruptures, 130 (62.5%) occurred during spontaneous labor reflecting 72% of scarred ruptures and 56% of unscarred ruptures.
It is interesting to note that 16% of unscarred ruptures (representing 4 unscarred women) and 9% of scarred ruptures (representing 16 scarred women) happened before the onset of labor (Zwart, 2009).
What I would do
If there was a medical reason for my baby to born (as detailed by the Mayo Clinic above), and it was the difference between a VBAC and a repeat cesarean, and I had a favorable Bishop’s score (download the app), I would consent to a foley catheter and/or low-dose Pitocin induction (not Cytotec or Cervidil).
If I was induced or augmented with Pitocin, I would be comfortable with continuous external fetal monitoring. Some hospitals do offer telemetry which is wireless monitoring giving you more freedom of movement. I’ve even seen telemetry in tube tops (naturally I can’t find a link to it now, if you have a link, can you leave a comment?) and units that can be worn in birth tubs. It’s good to call the hospital beforehand to determine what kind of telemetry monitoring units they offer and to confirm that it’s not lost in a closet.
There is no doubt that Pitocin is overused in America and often results in unnecessary emergency cesareans. However, it’s important not to cloud the two issues: medically unnecessary inductions and inductions with medical indication. There are situations where induction/ augmentation are reasonable and can give the mom one last option before having a cesarean. Thankfully, a low-dose Pitocin and/or foley catheter induction “remains an option” in women planning a VBAC according to ACOG. I think that is a good thing.
- Northern New England Perinatal Quality Improvement Networks’ (NNEPQIN) Guideline Suggestions for Elective Labor Induction
- Agency for Healthcare Research and Quality’s National Guidelines on the Induction of Labor
- ACOG’s Practice Bulletin No. 107: Induction of Labor