Sara610, glad your sister is asking. VBAC is a valid option. Check the ACOG (American College of Obstetrics and Gynecology www.acog.org
)guidelines. They have specific recommendations about VBAC and Cesarean prevention.
There is an organization , International Cesarean Awareness Network http//www.main.org/ican/ that has resources/websites for women looking for more info on VBAC and cesarean prevention. This is a grassroots, consumer based organization. They present many opinions as well as facts. Read with a critical eye. Some info is emotionally charged, but there also is much factual, extremely helpful info. This organization was very helpful to me in my search for a VBAC several years ago.
Your sister needs as much education on the subject as possible to make an informed decision. Seek information from a variety of sources. Once she knows her options, based on facts, then she can make a decision that she can live with. At least then she has had a say so in the matter.
I strongly suggest a midwife's care and the services of a doula or trained labor support person to be with the laboring mom.
Had a VBAC myself many years ago. No problem, but took lots of planning, educating myself and asserting myself. Ended up switching docs and hospital. Final plans weren't in place till 6 weeks before due date. Had a wonderful VBAC experience.
Also had a friend whose planned VBAC resulted in cesarean after a long, long labor. Third and fourth babies were VBAC (after 2 c-sections)
A lot of the decision to have a VBAC or repeat cesarean depends on the reason for the first C-section. Each labor is different.
"Failure to progress" in the first labor does not predict the events of a second labor. (I think "failure to progress" should be renamed "failure to wait".)
Feel free to PM me. I hope you and your sister find the info she needs to make the decision that is best for her.
If you don't know your options, then you don't have any.