Methods to prevent perineal trauma during childbirth include avoiding episiotomy and forceps delivery and slowing delivery of the head to allow the perineum time to stretch. Each intervention can lengthen the second stage of labor and change the biophysical stresses on infants and the pelvic floor. Available evidence supports the belief that the interventions are safe for infants and do not lead to significant short- or long-term maternal morbidity. We should abandon the conventional teaching that a longer second stage and perineal stretching are harmful. Routine episiotomy is no longer advisable. Forces that might inhibit physicians from practicing evidence-based techniques of obstetric delivery include time pressures, malpractice concerns, lack of experience with slow perineal stretching, and an interventionist practice pattern. Changes in practice can be effectively introduced through consumer pressures, opinion leaders, and in teaching institutions, by house staff.