ABSTRACT
A common cause of dystocia is cephalopelvic disproportion, characterized by a disparity between the size of the maternal pelvis and the fetal head, which therefore precludes vaginal delivery (Figures 12.1 and 12.2). An early diagnosis of this condition-that is, prior to the onset of labor-is difficult. Another common cause of dystocia is a slower than normal progression (abnormal progression of the fetus) or the complete stoppage of the presenting part (failure to progress) in the birth canal. Both of these labor abnormalities can only be diagnosed when the expectant mother is in the active phase of labor (Figure 12.3).
