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Am I at Risk?

Uterine rupture is not limited to women with a previous caesarean scar. While a prior uterine surgery is one of the most important risk factors, there are a number of other, less well-recognised factors that can also increase the likelihood of rupture.

It’s also important to understand that risk is not fixed. It can change over the course of pregnancy and during labour, depending on how the uterus is responding and how labour is managed.

The sections below explain the main factors that may influence risk.

Key Information

  • Risk depends on a combination of medical history, uterine structure, pregnancy conditions, and how labour is managed
  • No single factor determines safety; risks are cumulative.
  • Some types of scars and surgical histories carry higher risk than others.
  • Induction and augmentation increase the risk of rupture, especially in scarred uteri.
  • Understanding these risks supports informed consent and safer birth planning.
1. Uterine Scars & Surgical History
Type of Previous Caesarean Section

The type of incision made in the uterus during a previous caesarean affects risk:

  • Low transverse incision: generally lower risk; a vaginal birth may be considered in some cases.
  • Classical (vertical) incision: high risk; labour is usually not recommended.
  • T or J extensions: increased risk depending on depth and location.
  • Fundal or upper-segment incisions: high risk; elective caesarean recommended.
Other Uterine Interventions

Procedures involving the myometrium can weaken the uterine structure:

  • Myomectomy (removal of fibroids)
  • Metroplasty (surgery to correct the shape of the uterus)
  • Septum resection
  • Perforation during a procedure
  • Repeated or complex D&C’s
  • Previous rupture repair

The depth and number of incisions are important predictors of risk.

Quality of Scar Healing

Not all scars heal in the same way. Factors that may compromise healing include:

  • Single-layer closure
  • Infection after surgery
  • A collection of blood at the scar (hematoma)
  • Poor or delayed healing
  • Caesarean scar defects (isthmocele)

Women with known scar defects or very thin residual myometrium may have elevated rupture risk and may be advised against TOLAC.

Inter-Pregnancy Interval

A short interval between pregnancies or surgery may increase rupture risk because the scar has not fully healed. It is generally recommended to wait 12 months between a caesarean section and conception.

Müllerian Anomalies

Uterine malformations (such as bicornuate, septate, unicornuate, or didelphys uteri) are still poorly researched, but current understanding suggests that they may:

  • Create areas of focal weakness within the uterine wall
  • Alter how pressure is distributed as the uterus expands or contracts during labour
  • Increase the risk of uterine rupture, even in the absence of a prior surgical scar

Connective-Tissue Disorders

Conditions such as Ehlers–Danlos or Marfan syndrome may:

  • Reduce collagen strength
  • Impair scar healing
  • Increase susceptibility to uterine distension and tearing

Cesarean Scar Defects (Isthmocele)

An isthmocele is a small indentation or pouch in the uterine wall after a caesarean.

This may:

  • Weaken the lower uterine segment
  • Increase risk of rupture or dehiscence
  • Complicate decisions around labour

Endometriosis, Adenomyosis & Fibroids

These conditions may affect tissue quality and contribute to abnormal healing or focal thinning of the myometrium.

Induction of Labour

Induction can increase the risk of uterine rupture because it strengthens contractions and places additional stress on the uterine wall. This risk is higher in women with a uterine scar, but it is not limited to this group.

In women with a uterine scar, induction is consistently associated with a higher risk of rupture, particularly when:

  • medications such as prostaglandins are used (including misoprostol)
  • higher or more aggressive doses of oxytocin are required
  • multiple methods are used together (for example, combining mechanical and medication-based methods)

Even lower doses of oxytocin carry a higher risk compared to labour that starts naturally.

Augmentation of Labour

Augmentation means strengthening contractions once labour has started, usually with oxytocin.

Stronger or more frequent contractions place additional pressure on the uterus. This can increase the risk of rupture, particularly if contractions become very frequent or feel “non-stop”.

Because medications used to start or strengthen labour act directly on uterine contractions, careful monitoring is essential. Signs of excessive, very frequent, or “non-stop” contractions or maternal or fetal distress should always be taken seriously, even in women with no other known risk factors for rupture.

Prolonged or Obstructed Labour

Risk increases when:

  • Labour progresses unusually slowly
  • The baby is malpositioned
  • Contractions are strong but ineffective
  • Contractions become very frequent or feel “non-stop” (hyperstimulation)
Placental Positioning

A placenta that sits low in the uterus or over a previous scar may indicate an area of weaker tissue.

Placenta accreta spectrum (where the placenta grows too deeply into the uterine wall) is also associated with a higher risk of rupture.

Fetal Factors

Certain factors can increase pressure on the uterus, including:

  • larger babies
  • unusual positions (such as breech or transverse)

These can make labour more difficult and increase strain on the uterine wall.

Overstretching of the Uterus

When the uterus is stretched beyond its usual limits, it may be less able to tolerate pressure.

This can happen with:

  • excess amniotic fluid (polyhydramnios)
  • larger babies
  • multiple pregnancy (twins or more)
  • having had several previous births
Maternal Health Factors

Some conditions may influence risk by affecting tissue strength or labour progression, including:

  • Advanced maternal age
  • Gestational diabetes
  • Hypertension or pre-eclampsia
  • Obesity or low BMI, depending on context

A previous uterine rupture is one of the strongest predictors of recurrence.

The level of risk depends on where the rupture occurred and how it was repaired. Because of the high risk of recurrence, labour is not recommended, and delivery is planned by caesarean before labour begins.

Care should always be individualised, based on your medical history and specialist advice. For more detailed information on planning a future pregnancy, see the Pregnancy After Rupture page.

What Happens During a Rupture?

Understanding your personal risk is the first step. The next page, What Happens During a Rupture, explains the physical event itself: what occurs inside the uterus, how blood flow is disrupted, how the fetus is affected, and why rapid intervention is critical.

This clear breakdown helps families and clinicians recognise the urgency of rupture and understand why each risk factor matters.

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