You are caring for Carla, a 23 year old G1P0 who is being induced for post dates. Carla has a history of herpes simplex virus but no active lesions at this time. The fetal heart rate (FHR) is very difficult to trace. You have to consistently adjust the ultrasound to obtain the FHR. One of the nursing students on the unit asks why you don't place a fetal scalp electrode. Your best response is