Kmom gives revealing definitions of failure to progress & CPD at her site PlusSizePregnancy
:Failure to Progress
(FTP) - also known as labor dystocia. This occurs when labor deviates from a normal or average pattern of labor, but is strongly subjective and differs greatly from one provider to the next. Midwives often call this "Failure to Wait" by the physician, since it can result from an impatient doctor or one who does not recognize that labors that deviate from the 'normal' labor are not necessarily pathological. Just what constitutes a normal labor and an abnormal labor that needs intervention is highly controversial and will differ significantly from provider to provider. True FTP can occur, of course, but it is difficult to separate out the cases that are caused by obstetric mismanagement vs. naturally-occuring cases. Common in induced labors.Cephalopelvic Disproportion
(CPD)- a baby that is 'too big' for the mother's pelvis. This is a catch-all phrase that doesn't have a lot of meaning; the baby's presentation and position usually has more to do with CPD than the actual size of the baby. An 8 lb. baby that is malpresenting, for example, is likely to get stuck, whereas a 9+ lb. baby that is perfectly positioned and where the mother gets to use optimal delivery positions is likely to come right out. Many women who are given a c-section for CPD and told that their pelvises are 'too small' actually go on to later deliver a baby vaginally that is much bigger. The presentation/lie of the baby, maternal positioning, and forcing labor unnaturally are the keys in many cases. True CPD can occur, but is usually seen in mothers who have had pelvic injury or disease, had rickets, or who were chronically malnourished as children, although it is possible occasionally in normal circumstances too. CPD is most often actually a case of cephalopelvic malpresentation or 'failure to wait' by the physician, but this is often overlooked as a cause.
In the old days there was no "active management of labor" i.e. time limits. There was no one waiting for you to pass the allowed time limit with a scalpel in hand telling you your body couldn't birth.