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2. Difficulty in delivery of fetal shoulders
Failure to deliver fetal shoulder without utilizing facilitating maneuvers
Prolonged head-to-body delivery time
>60 seconds
Incidence: 0.2-3% of all live births; represents an obstetric emergency
Shoulder 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.

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