Difficulty in delivery of fetal shouldersFailure to deliver fetal shoulder without utilizing facilitating maneuversProlonged head-to-body delivery time

>60 secondsIncidence: 0.2-3% of all live births; represents an obstetric emergencyShoulder dystocia results when, after delivery of the fetal head, either the anterior shoulder, posterior shoulder, or both, fail to delivery with the normal movements and forces of delivery. The anterior shoulder is most commonly impacted. This problem results from a size discrepency between the maternal pelvic inlet and the width of the fetal shoulders. 

The incidence of shoulder dystocia is difficult to calculate due the subjective nature by which it is reported. A range of 0.2% to 3.0% of all vaginal births has been reported in the literature, dependent upon the criteria used to define it.

Shoulder dystocia complicates 0.6 to 1.4% of vaginal deliveries of fetuses in the vertex presentation.