A prospective study of the progress of
labor in 220 nulliparous women and 99 multiparous women who spontaneously entered
labor evaluated the benefit of prolonging oxytocin
augmentation for an additional 4 hours (for a total of 8 hours) in patients who were dilated
at least 3 cm and had unsatisfactory progress (either protraction or arrest) after an initial 4 - hour
augmentation period (21).