Follow up to earlier question about c-sections and time elapsed between pregnancies?

A little while ago I asked a question about if VBACs were more successful if pregnancies are spaced quite far apart. UKNurse answered that it depends on what the cause for the first c-section was, that if it was a case of a pelvis being too small then there's nothing that can be done about that and it will be another c-section. What if that was the case (that the original c section was because of a too small pelvis) but on the second time around the mother went into labor prematurely and wound up having, say, a six pound baby instead of a nine pound baby. Would she most likely be able to deliver naturally under those circumstances, if the baby was much smaller? Would the doctors at least give her a chance since the baby is smaller, or would they wheel her right into surgery?