A 37 yo primigravida undergoes IOL at 39 weeks. After 4 hours of second stage, she has a forceps-assisted vaginal delivery of a male infant weighing 4200g. Delivery is complicated by a shoulder dystocia and neonatal humerus fracture. Delivery ultimately occurred after lateral traction of the fetal head, McRoberts maneuver, suprapubic pressure, rotation of the fetal shoulders and delivery of the posterior arm. After delivery, the newborn is diagnosed with a brachial plexus injury. In this patient, the action that has been shown to increase infant brachial plexus stretching is: