Are there any studies that look at "which factors decrease the rate of uterine rutpture?" For example being healthy, normal weight...ect? Thanks, Bethany
You bet! Although before giving a list, you should know that most risk factors don't increase risk of the scar giving way, that any increased risk must be balanced against the increased risks of accumulating cesarean surgeries, and that having a VBAC is protective against having a scar rupture in future labors.
That being said, very short intervals between pregnancies has a higher risk of scar rupture than longer intevals. Studies used different cutoffs, but we're not talking huge differences in child spacing, just 18 mos or more.
Another major modifiable factor is induction, especially with an unripe cervix. The use of cervical ripening agents increases risk over oxytocin (Pitocin, Syntocinon) alone for induction, but it isn't clear whether this is because these agents are used when the cervix isn't ripe, the agents can soften the connective tissue in the scar right along with the connective tissue in the cervix, or both. (FYI: Women planning VBACs are not infrequently told they must deliver by 41 weeks in the belief that they are at greater risk of scar rupture, but the linkage between scar rupture and pregnancies of 41 weeks or more is because women with pregnancies beyond 41 weeks are more likely to be induced.) In most cases awaiting labor is as safe or safer than elective repeat cesarean, and in women with medical indications for induction, it can be a better option than repeat cesarean surgery. The risk is in women whose uteruses are not ready to labor or who are subjected to high-dose/short-interval oxytocin regimens, that is regimens not grounded in our understanding of how the uterus responds to oxytocin. Induction can be done safely if it is done with care.
In addition, augmenting labor with oxytocin has also been associated with excess scar ruptures in some studies. I would bet that this also has to do with using high-dose/short-interval oxytocin regimens (A.K.A. "active management of labor). Here, too, patience and simple measures such as walking often will do the trick, but when necessary, giving Mother Nature a gentle nudge will generally be better than elective repeat cesarean surgery.
And, of course, taking good care of yourself physically and emotionally so that you have a strong uterus prepared to work well and efficiently and you've addressed any emotional fallout that might get in your way during labor has to be all to the good.