If you're planning a Vaginal Birth After Cesarean, you know that the most common concern that mothers and doctors have about VBAC is the increased risk of uterine rupture. Uterine rupture can be very scary and confusing. The more you talk about it, the more confused you might feel. The trouble with uterine rupture is much of the data is outdated, pulled from poorly designed studies, and does not even clearly define "uterine rupture". So today, I'd like to help you learn more about uterine rupture by discussing three important uterine rupture facts every mom planning a VBAC should understand.
Uterine Rupture Fact #1: Uterine Rupture and Uterine Dehiscence are not the same thing
The first reason studies on uterine rupture can be misleading is that some studies do not differentiate between uterine rupture and uterine dehiscence. Conflating these two phenomenons inflates the perceived risk of uterine rupture when, infact, many women included in the data did NOT experience uterine rupture. Uterine rupture is defined as a full thickness separation of the uterine wall. Simply put, every layer of the uterine wall separates, tears, opens up and there is a gaping hole in the uterus. This is extremely dangerous and can cause hemorrhaging, fetal hypoxia, and even fetal death.
On the other hand, Uterine Dehiscence is a partial thickness separation of the uterine wall, sometimes referred to as a "uterine window" because surgeons can usually see the baby through the uterus. While there is a lot of controversy about conflating these two ideas, and whether or not uterine dehiscence is likely to turn into a uterine rupture, it is critical to understand that these two conditions are NOT the same, so if you're looking at a study on uterine rupture, it is critical to understand whether the study combines these two conditions or differentiates them.
Uterine Rupture Fact #2: Uterine Rupture is least common in SPONTANEOUS labor after cesarean
While there are many studies that cite a range of statistics for uterine rupture, when we break the numbers down with more scrutiny and nuance, we see that the incidence of Uterine Rupture for spontaneous labor is around 4 in 1000 (or 0.4%).
For augmented labors (aka labor started naturally but providers use medical intervention to "speed up" labor) the Uterine Rupture rate increases to approximately 9 in 1000, and for induced VBAC labors the Uterine Rupture rate is around 10 in 1000 (1%). Now, these numbers change when we discuss labor induction methods and other variable circumstances. For instance, one study published in January 2022 suggested a 0.4% uterine rupture rate in BOTH the spontaneous labor group AND the Pitocin Induction Group. The take away here is that while induction can be a safe option in necessary situations, you're less likely to experience uterine rupture if you wait for labor to start naturally versus scheduling an induction.
Uterine Rupture Fact #3: There is a 2.8% perinatal mortality for victims of uterine rupture.
While the low likelihood of uterine rupture may be starting to comfort you, you might also be thinking "well what if I am that one percent? Then what?" While I'm not minimizing the trauma and seriousness of uterine rupture at all, the good news is that 97% of full term births that experience uterine rupture will survive. The perinatal mortality (fetal death occurring during labor or within 28 days of birth) rate associated with uterine rupture is 1 in 16 overall (including premature births), and 1 in 32 for term births. Of course there are other complications that can occur such as mother hemorrhaging, requiring a hysterectomy, oxygen deprivation for baby leading to birth injury, etc. At this time I am unaware of solid statistics for these circumstances, but if I come across them I'll eagerly add them to this post. Jen Kamel from VBAC Facts did some awesome math on this statistic, applying it to Landon's 2004 study citing a 0.7% Uterine Rupture Rate, and estimated that the rate of perinatal mortality due to uterine rupture is about 1 in 2380 to 1 in 5100. That's like a 0.0004% likelihood of experiencing perinatal death due to uterine rupture.
How have your thoughts on Uterine Rupture and VBAC Risk changed?
While this low statistic doesn't minimize the reality that this tragedy CAN occur, it might help you put the likelihood into perspective. Do these numbers sound like numbers that we should all be TERRIFIED of, and giving our rights up over? For me personally, that's a risk I'm willing to take, since I know no birth is without the possibility of tragedy. These numbers, however, can help alleviate the fear you might be feeling over uterine rupture so that you can start making your VBAC birth plan decisions from a place of INFORMATION and INTUITION, not fear. Do me a favor an pop over the the FREE VBAC Support Group on Facebook and let me know how these numbers changed your thought process on Uterine Rupture and VBAC!