The risk of rupture is higher with vertical scars if they extend into the upper uterus as during labour that part of the uterus is more active and thus more vulnerable. Because of that if a vertical scar does rupture the outcomes aren't as good - the strong action tends to open a large rupture whereas a low scar may only open small "windows". A low vertical scar has a rupture risk similar to that of a low transverse scar, around 0.6-1.2%, a vertical scar which extends up into the upper uterus carries the risk of around 3-5% (though some studies say as much as 12%), and the classical (T-shaped) and J-incisions have a rupture risk of 9-14%. Wombles you'll be able to find out from your notes from last time (you can get them by writing to the hossie where you had #1) whether yours was a low-vertical or standard vertical incision (you can't tell by looking at the outer scar, it's only the scar on the uterus which matters) or failing that a scan can find the scarline to assess it. Bear in mind that the numbers above represent all ruptures, including "silent" ones which have no symptoms, cause no problems and are discovered after birth by scans to check the scar. This bumps up the numbers quite significantly in terms of actual violent ruptures (the dangerous kind the obs threaten you with), though as i said the ruptures of vertical and classical or J-incisions tend to be the more dangerous kind if they do occur.

Even with a classical or J-shaped scar VBAC is VERY possible, but it is best to be fully aware of the risks and possibilities when making that decision. You might find an Ob will say "vertical incision=repeat section" or you might not, but knowing the FACTS about it will empower you to make your decisions whatever happens. Congrats on your PG hun

Bx