Low Transverse Incision
A horizontal surgical incision made across the lower, thinner portion of the uterus during a cesarean delivery. This type of uterine incision carries the lowest risk of rupture during subsequent labor compared with other common cesarean incision types (ACOG, 2017B).

Spontaneous Labor
Labor that begins naturally without medications or medical procedures used to initiate contractions. Labor may begin spontaneously and subsequently require augmentation (ACOG, N.D.).

Augmentation
The use of medications, such as Pitocin, or procedures, such as artificial rupture of membranes, to increase the strength or frequency of contractions after labor has already begun (ACOG, N.D.).

Induction
The use of medications or medical procedures to initiate labor before it begins spontaneously. Methods may include Pitocin, prostaglandins, mechanical cervical dilation, or artificial rupture of membranes (ACOG, N.D.).

Prostaglandins
Hormone-like substances involved in cervical ripening and uterine contractions. Synthetic prostaglandin medications, including misoprostol and dinoprostone, may be administered to soften the cervix and help initiate labor (ACOG, 2022).

Contraindication
A medical condition or circumstance in which a particular medication, treatment, or procedure should not be used because it may cause harm (NCI, N.D.).

Retrospective Study
A research study that examines previously occurring events or outcomes, often using existing medical records to investigate possible relationships between exposures and outcomes (National Guideline Centre, 2016).

Prospective Study
A research study that follows participants over time, collecting information and recording outcomes as they occur (National Guideline Centre, 2016).

Mechanical Dilation
A method of cervical ripening that uses devices, such as a Foley balloon catheter or cervical dilators, to physically open or soften the cervix in preparation for labor (ACOG, 2022).

Systematic Review
A structured evaluation of existing research addressing a specific question. Researchers use predefined methods to identify, select, assess, and summarize relevant studies. A systematic review may also include a statistical meta-analysis (IOM, 2011).

This spotlight review focuses specifically on the use of Pitocin during a trial of labor after cesarean (TOLAC). The evidence presented is relevant to families planning a vaginal birth after cesarean (VBAC).

This is not a comprehensive contextual review of VBACs or TOLACs. A full review is currently in development at The Birth Review and is expected to be published in early 2027.

A VBAC (Vaginal Birth After Cesarean) refers to a vaginal birth following a previous cesarean delivery. A TOLAC (Trial of Labor After Cesarean) refers to the attempt to give birth vaginally, regardless of whether that attempt ultimately results in a vaginal birth or another cesarean (ACOG, 2019).

For many women, a VBAC is a reasonable alternative to a repeat cesarean. Successful VBACs are associated with shorter recovery times, fewer surgical complications, and reduced risks associated with multiple cesarean deliveries (ACOG, 2019).

One of the primary concerns surrounding a TOLAC is uterine rupture, a rare but potentially life-threatening complication in which the uterine wall tears completely through its layers. This most commonly occurs along the scar left by a previous cesarean incision.

Complete uterine rupture differs from uterine dehiscence, which refers to an incomplete separation or thinning of the uterine wall. Dehiscence does not extend through all layers and is generally less dangerous than a complete rupture (TOGIOKA & TONISMAE, 2023).

The primary concerns with a complete uterine rupture are:

Uterine rupture requires urgent medical attention, typically including an emergency cesarean delivery. Although serious complications can occur, most mothers and babies experiencing a rupture recover well (RCOG, 2026).

The American College of Obstetricians and Gynecologists (ACOG) reports an overall uterine rupture risk of approximately 0.5–0.9% for women attempting VBAC with a previous low-transverse cesarean incision. However, ACOG also references research showing that rupture rates differ considerably depending on labor interventions, ranging from 0.4% during spontaneous labor without augmentation to 1.4% during induction involving prostaglandins, with or without Pitocin (ACOG, 2017A).

Similarly, RCOG estimates that uterine rupture occurs in up to 0.5% (1 in 200) of women planning a VBAC. This represents approximately 5 women out of every 1,000 (RCOG, 2026). However, they note that labor induction can increase uterine rupture risk by approximately two to three times, depending on the method used (RCOG, 2026).

In this review, we will take a closer look at the evidence cited here, along with additional evidence and context. Given this variation in risk, it is important to understand the distinction between spontaneously initiated labor and medically induced or augmented labor when interpreting VBAC risk statistics.

ACOG (American College of Obstetricians and Gynecologists) recognizes TOLAC as an appropriate option for many women with a previous cesarean delivery. Its Practice Bulletin No. 205, reaffirmed in 2024, explains that successful VBAC is associated with reduced maternal complications and fewer complications in future pregnancies.

ACOG also emphasizes that a TOLAC ending in an unplanned cesarean carries greater maternal and infant risks than either a successful VBAC or a planned repeat cesarean (ACOG, 2019). The Birth Review will cover this more extensively in our VBAC Contextual Review publishing early 2027.

A successful VBAC is a vaginal delivery following one or more previous cesarean births. The term successful simply indicates that a vaginal birth occurred rather than another cesarean. Importantly, an unsuccessful TOLAC does not mean uterine rupture occurred. Most repeat cesareans following TOLAC are performed for other reasons, including stalled labor or concerns about the baby's heart rate, which can also lead to cesarean delivery in any labor (RCOG, 2026).

In a U.S. national study covering 2019–2022, 74.7% of TOLAC attempts resulted in a successful VBAC. Unrelated but for perspective, 73.4% of U.S. first-time mothers with term, singleton, head-down births delivered vaginally in 2024 (HIKADE ET AL, 2025; CDC, 2026).

Pitocin is a synthetic version of oxytocin, a naturally occurring hormone responsible for stimulating uterine contractions during labor.

Pitocin is administered intravenously (IV) and is commonly used for two purposes:

The amount administered can be adjusted throughout labor based on the mother's contractions and the baby's heart rate (ACOG, N.D.).

Although Pitocin can be effective in initiating or strengthening labor, it can also cause excessive uterine contractions, potentially affecting the baby's heart rate. For women attempting a VBAC, Pitocin exposure is particularly important because research has associated its use with increased uterine rupture rates (ACOG, 2024; LANDON ET AL., 2004). However, current ACOG guidelines do not classify Pitocin as generally contraindicated during TOLAC for eligible candidates (ACOG, 2025).

Cahill et al. (2007) reported Pitocin use in approximately 40% of TOLACs. Zhang et al. (2021) reported pooled Pitocin use of 39.8% among women entering spontaneous labor and 60.6% among women attempting a VBAC and undergoing induction.

Prostaglandins are naturally occurring hormone-like substances that help soften and dilate the cervix and stimulate uterine contractions during labor.

Synthetic prostaglandin medications are commonly used for cervical ripening and labor induction. Two common types include:

ACOG's 2025 guidance identifies misoprostol, and by extrapolation, other prostaglandin preparations as contraindicated for cervical ripening in patients with previous uterine surgery, including cesarean delivery (ACOG, 2025).

Current guidelines, stated in 2025, state against prostaglandin use during a TOLAC. Earlier research, including Landon et al. (2004), reported prostaglandin use in 19.7% of induced TOLACs.

The Birth Review examined 29 research publications, including observational studies, clinical trials, and systematic reviews. We selected 5 to include in this spotlight review based on their size, relevance to specific methods requiring evaluation, and clarity of intervention and outcome classifications.

Contextual Note: Studies sometimes use different definitions of uterine rupture, so not every published rupture percentage represents exclusively complete uterine ruptures. Observational studies can identify associations but cannot independently establish causation.

This retrospective study looks at spontaneous labor without Pitocin augmentation and compares it to labors augmented with Pitocin, induced with Pitocin alone, and labors induced with Pitocin alongside prostaglandins.

Relevant Evidence Limitations/Concerns: Observational data and does not establish causation.

Induction or Augmentation Rate: Of the women who entered labor, 75% began spontaneously and had no Pitocin augmentation. The remaining 25% received Pitocin augmentation or underwent induction using various methods, including methods without Pitocin or prostaglandins.

Population: 29,008 women whose first births were cesareans, including 10,958 who underwent labor during their second birth. Births occurred from 1998–2000 across four Australian states.

Total Ruptures Evaluated: 48 uterine ruptures, including 37 complete ruptures.

Bold represents statistics more relevant to families planning a VBAC today. ACOG (2025) identifies prostaglandin preparations as contraindicated for cervical ripening following previous cesarean delivery.

Additional Study Notes: Researchers reviewed hospital records to validate uterine rupture diagnoses rather than relying solely on administrative codes, although records were unavailable for six cases.

Unique Finding: Interestingly, the Pitocin augmentation group had a higher rupture rate than the Pitocin-only induction group. Contextual factors that could help explain this difference, such as Pitocin dosage and administration rate, were not available (DEKKER ET AL., 2010).

Evidence from this prospective observational study examines uterine rupture rates among women attempting VBAC. It compares spontaneous labor without Pitocin to labor augmented with Pitocin and labor induced using Pitocin, prostaglandins, or a combination of both.

Induction or Augmentation Frequency: Of the 12,694 women whose labor began spontaneously, 47.3% received Pitocin augmentation, while 52.7% did not. An additional 4,708 women underwent labor induction, and 496 were not classified and are not listed in the chart below.

Population: The study included 17,898 women attempting VBAC across 19 U.S. academic medical centers, including women who ultimately required a repeat cesarean. The number of previous cesareans and incision types varied. Births took place from 1999–2002.

Total Ruptures Evaluated: 124 symptomatic uterine ruptures.

Bold represents statistics relevant to families planning a VBAC today. ACOG (2025) identifies prostaglandins as contraindicated for cervical ripening following previous cesarean delivery.

Additional Study Notes: Researchers prospectively collected hospital data and distinguished spontaneous labor from augmentation and induction. Medical records were reviewed by trained research nurses, and uterine rupture cases underwent additional review.

Unique Finding: No ruptures were recorded among the 227 women receiving prostaglandins alone. However, this small sample is insufficient to establish safety (LANDON ET AL., 2004).

Evidence from this systematic review and meta-analysis examines uterine rupture risk among TOLACs without Pitocin as well as with Pitocin (used for augmentation or induction).

Relevant Evidence Limitations/Concerns: The review did not separately account for other induction interventions, including prostaglandins or mechanical dilation, when comparing Pitocin exposure. The included studies also varied in their methods and patient populations. Induction and augmentation were combined into one Pitocin-use group, and three studies did not clearly define uterine rupture (ZHANG ET AL., 2021). The potential use of prostaglandins, which ACOG now contraindicates for cervical ripening following cesarean delivery, may limit how closely these findings reflect current practices (ACOG, 2025). Evidence is observational and does not establish causation.

Induction or Augmentation Frequency: The researchers reported that approximately 40% of women whose labor began spontaneously received Pitocin for augmentation, while approximately 60% of women undergoing induction received Pitocin.

Population: This review examined 48,457 women attempting VBAC with one previous low-transverse cesarean incision across 14 observational studies. Previous vaginal births were not excluded. The studies included women regardless of whether they experienced uterine rupture, achieved a VBAC, or ultimately required another cesarean.

Total Ruptures Evaluated: 264 uterine ruptures.

These comparisons are calculated from the rounded pooled rupture rates, rather than a pooled or adjusted risk ratio.

(ZHANG ET AL., 2021)

Here we examine retrospective observational evidence showing the associated relationship between varying levels of Pitocin exposure and uterine ruptures in TOLACs.

Relevant Evidence Limitations/Concerns: The study did NOT establish whether other labor inducing methods, primarily prostaglandins which are now contraindicated for TOLACs, were used alongside Pitocin. The associated rupture rates per dose are not established rates and they do not confirm causation.

Induction or Augmentation Frequency: Approximately 40% of women received Pitocin during labor. The researchers did not clearly separate Pitocin induction from augmentation in the overall exposure comparison.

Population: 13,523 women attempting VBAC across 17 U.S. medical centers, including women who ultimately required a repeat cesarean. Recorded births occurred from 1996–2000.

Total Ruptures Evaluated: 128 uterine ruptures.

Additional Study Notes: Researchers adjusted for several potential confounding factors, including previous vaginal delivery and whether labor was induced or augmented.

Unique Finding: Uterine rupture rates increased with higher maximum Pitocin doses, reaching 2.07% at 21–30 mU/min. The highest dosage group had approximately three times the adjusted odds of rupture compared with women who received no Pitocin.

(CAHILL ET AL., 2007)

Here we examine observational evidence from a systematic review to look closer at escalation intervals (time between increasing doses) of Pitocin during TOLACs.

Relevant Evidence Limitations/Concerns: The studies used varying Pitocin protocols, and the available report does not establish that all studies consistently distinguished complete uterine rupture from uterine dehiscence. Differences in patient characteristics and reasons for Pitocin administration may also influence the findings. Researchers emphasized that stronger evidence is needed to identify the safest dosing protocols. Additionally, the review did not establish that the use of prostaglandins was excluded. Although the review was published in 2026, it includes births from previous years before ACOG stated prostaglandins as contraindicated for TOLACs.

Induction or Augmentation Frequency: Not published.

Population: 51,511 women attempting TOLAC across 21 observational studies. Births ranged from 1980 - 2021 and consisted of women not exclusively with one prior cesarean.

This is approximately 88% higher odds, not an 88% increase in absolute rupture risk. The estimate is from a sensitivity analysis comparing Pitocin exposure with a spontaneous TOLAC reference group—not a direct comparison of the two escalation intervals (NICOLÌ ET AL., 2026).

Research demonstrates a clear association between Pitocin use, whether for induction or augmentation, and increased uterine rupture risk among women attempting vaginal birth after cesarean (VBAC).

Higher maximum Pitocin doses are also associated with increased rupture risk, as are dosing protocols that increase Pitocin more frequently than every 30 minutes. These findings suggest that both Pitocin exposure and how it is administered may influence uterine rupture risk during a TOLAC.