*Edited to add: While I emphasized this many times throughout the post, it has been brought to my attention that others are sharing this as a VBAC only post/percentage. I want to clarify that .07% is for all pregnant women, including no previous scarring, scarred from any trauma, VBAC and anomalies (.012 when only non scarred and .07 with all). VBAC rupture rate is closer to .3-.5%. Still very small, but higher when isolated to just VBAC’s.

Uterine rupture has become a big risk over the last few decades. At least that is what pregnant women are told. Especially for moms who want to birth vaginally after a previous cesarean section. A cesarean is major surgery and a scar and scar tissue are a result. The body is amazing and can heal and adapt very well. Just how much of a risk is uterine rupture to a mother?

I found this article recently on Medscape Reference. It is a summary of what 20 peer-reviewed publications have found when it comes to uterine rupture in pregnancy and birth. Let’s break it down.

Sources

The peer-reviewed literature was searched using the PubMed, Medline, and Cochrane databases for all relevant articles published in the English language. The search terms were uterine rupture, pregnancy and prior cesarean section, vaginal birth after cesarean, VBAC, trial of labor (TOL), trial of labor after cesarean (TOLAC) uterine scar dehiscence, and pregnancy and myomectomy. Standard reference tracing was also used. Articles published from 1976-2010 that described the incidence of uterine rupture and that included sufficient information regarding the authors’ definitions of uterine rupture and of uterine-scar dehiscence were incorporated for review. All studies were observational or reviews. A total of 109 published articles were included for data extraction and analysis.

It is important to know where and how a study (or studies) were done when citing them. There are many factors to consider in how the results were found. These studies were all taken from medical sources and peer reviewed.

Overview

From 1976-2009, 20 peer-reviewed publications that described the incidence of uterine rupture reported 1,864 cases among 2,863,330 pregnant women, yielding an overall uterine rupture rate of 1 in 1,536 pregnancies (0.07%).

We are looking at a large number of women. Almost 3 million! The overall uterine rupture was .07%. Now do we want this to happen at all? Of course not. Anything can happen in life, including when birthing. I trust birth. I respect birth. For birthing women, it is not 1%, not .5%, not even .1%, but .07% of women can experience uterine rupture.

The initial signs and symptoms of uterine rupture are typically nonspecific, which makes diagnosis difficult and sometimes delays definitive therapy. From the time of diagnosis to delivery, only 10-37 minutes are available before clinically significant fetal morbidity becomes inevitable. Fetal morbidity occurs as a result of catastrophic hemorrhage, fetal anoxia, or both. The inconsistent premonitory signs and the short time for instituting definitive therapeutic action make uterine rupture a fearful event.

If a woman starts to have a uterine rupture, there are few signs. A skilled midwife or OB may know what to look for and at the first sign of something wrong, take action. In this .07%, there is 10-37 minutes to get baby out. When uterine rupture does happen, it needs to be addressed quickly, because if not, baby can die. This is why it is so feared (understandably so).

Definition: What is Uterine Rupture?

Uterine rupture during pregnancy is a rare occurrence that frequently results in life-threatening maternal and fetal compromise, whereas uterine scar dehiscence is a more common event that seldom results in major maternal or fetal complications. By definition, uterine scar dehiscence constitutes separation of a preexisting scar that does not disrupt the overlying visceral peritoneum (uterine serosa) and that does not significantly bleed from its edges. In addition, the fetus, placenta, and umbilical cord must be contained within the uterine cavity, without a need for cesarean delivery due to fetal distress. By contrast, uterine rupture is defined as a full-thickness separation of the uterine wall and the overlying serosa. Uterine rupture is associated with (1) clinically significant uterine bleeding; (2) fetal distress; (3) expulsion or protrusion of the fetus, placenta, or both into the abdominal cavity; and (4) the need for prompt cesarean delivery and uterine repair or hysterectomy. Although a scar from cesarean delivery is a well-known risk factor for uterine rupture, most events that involve disruption of the uterine scar result in uterine-scar dehiscence rather than frank uterine rupture. These 2 entities must be clearly distinguished because the options for clinical management and outcomes differ significantly.

From this we know that uterine rupture is RARE, but can be fatal very quickly. It is also noted that uterine scar dehiscence is different than uterine rupture. It can be controlled easier and is usually not fatal. If a true uterine rupture occurs, a cesarean section will be needed to save baby and to address the rupture and heal the mother.

Also important to note is that most of the time, even with a previous cesarean section, it is a uterine dehiscence, not a rupture. They are significantly different!

Percentages Found

Meta-analysis of pooled data from 20 studies in the peer-reviewed medical literature published from 1976-2009 indicated an overall incidence of pregnancy-related uterine rupture of 1 per 1,536 pregnancies (0.07%). When the studies were limited to a subset of 8 that provided data about the spontaneous rupture of unscarred uteri in developed countries, the rate was 1 per 8,434 pregnancies (0.012%).

Like previously stated, the risk of uterine rupture in all cases (VBAC, previous cesareans, etc.) is very low at .07%! When they limited the studies to only 8 studies about spontaneous rupture of a uterus that has not been previously scarred, the rate lowered to .012%. So with all factors, including previous cesareans, the rate does rise, but it is still under .1%!

Risk Factors

Congenital uterine anomalies, multiparity, previous uterine myomectomy, the number and type of previous cesarean deliveries, fetal macrosomia, labor induction, uterine instrumentation, and uterine trauma all increase the risk of uterine rupture, whereas previous successful vaginal delivery and a prolonged interpregnancy interval after a previous cesarean delivery may confer relative protection. In contrast to the availability of models to predict the potential success of a TOL after a prior cesarean section, accurate models to predict the person-specific risk of uterine rupture for individuals are not available.

There are many factors taken into consideration in the .07% including uterine anomalies, myomectomy, number and type of cesarean births, induction and more. That’s right, it’s not even just about cesareans. In that .07%, it includes complications for anomalies, traumas from car accidents or falling and INDUCTIONS!

What lowers risk? Previous vaginal births and more time to heal between a cesarean and subsequent pregnancies. There are also unique characteristics to every women’s body, history and pregnancy.

Summary

Even when taking in ALL factors of any kind of situation, after looking at multiple peer reviewed research and 2.8+ million women’s pregnancies and birth, the chance of a uterine rupture is significantly LESS than 1%. It is LESS than .1%! It is .07%.

If you want to have a VBAC, find a care provider (midwife or OB) that is competent and supportive. Show them the research, talk about how to reduce the risk (even though small) of uterine rupture for you and birth your baby without fear!