[Risk factors and neonatal outcomes in shoulder dystocia]

Shoulder dystocia (SD) is a rare obstetrical complication but linked with a high perinatal morbidity and mortality rate. SD has been associated to a series of maternal and fetal risk factors due to a multifactorial etiology. This study analyzes the incidence of SD, its morbidity and associated risk factors.

Cases of SD occurred at the St. Gerardo Hospital (Monza) between January 1992 trough December 1997 have been retrospectively reviewed. Obstetrical and feto-neonatal data regarding cases of SD were compared to data regarding all the cephalic vaginal deliveries occurred in the same period in our Center.

A total of 14,157 cephalic vaginal deliveries were included in this study, of these 21 infants (0.15%) had SD. A significantly higher incidence of SD cases was found in fetal macrosomia, maternal diabetes, induction of labor by PGE2, use of obstetrical vacuum, length of first stage of labor > 4 hours in multiparas and > 8 hours in nulliparas, and length of second stage > 60 minutes, regardless of parity. A closed association was also observed between SD and birth trauma as brachial plexus injury and humerus fracture.

The incidence of SD in our population (0.15%) is below the average reported in the literature (0.37-1.1%). The well-known risk factors, whose low positive predictive value can nevertheless modify obstetrical management, are confirmed.