Many moms do not go into labor expecting to have a c-section. It does happen and it has been happening more frequently in recent years. There has been an increase in the amount of c-sections performed in the United States. Also, is the fact that for many years there has been the belief that once a woman has had a c-section she should always have a c-section, but there are options out there for women to have a vaginal birth after a cesarean (VBAC).
VBACs are not performed by all doctors because of the risk of rupture of the prior c-section scar. The fact is that it has happened in the past and the possibility of the scar rupturing is possible. However there are many moms that have been able to successfully have a VBAC. There are even a few moms that have had VBAC after have 2 c-sections. The risk of uterine rupture does increase with the amount of prior caesarean scars.
Several resources are available across the web with detailed information about having a VBAC.