Box 1. Major risk factors for shoulder dystociaand Erb palsy.History• History of shoulder dystocia or baby with BPI• Maternal diabetes• Maternal obesityAntepartum factors• Macrosomia (risk increases as fetal weightincreases)• Gestational diabetes• Excessive weight gainIntrapartum factors• Clinical pelvimetry and estimated fetal weightconcerning for CPD• Protracted active phase dilatation• Arrest of dilatation• Prolonged deceleration phase• Failed, protracted or arrested descent• Long second stage• Precipitate second stage• Instrumental deliveryBPI: Brachial plexus injury; CPD: Cephalopelvic disproportion.