The best way to avoid serious perineal damage is to create the conditions for an authentic 'fetus ejection reflex.' This means that the baby is born after a very short series of irresistible contractions without any room for voluntary movements. In this case the mother, who is 'on another planet,' is able to find a complex posture perfectly adapted to the particular case. It is usually an asymmetrical bending forward posture. Very few people can understand what a fetus ejection reflex is because it is more often than not transformed into a second stage of labor with voluntary movements. It does not occur if there are several persons around. It does not occur if there is a birth attendant who behaves like a guide, or a 'coach,' or a support person. It does not occur if somebody wants to 'take care of the perineum.' It does not occur in the presence of the baby's father. The best situation I know for a fetus ejection reflex is nobody around, but an experienced, low-profile, motherly, and silent midwife... a midwife able to remain silent even when the mother-to-be says silly words, such as, for example, "kill me," "let me die," etc... a midwife who will just make sure that the baby will not fall down on the floor.
With my second birth my body started the FER (fetal ejection reflex) on the way to the birth center in the car, with just DH there. FER is a force to be recognited with! He was born about 4mins after I got to the BC, he literally surfed on out! There was no telling me how to push, only to pant when he was crowning to try to prevent tearing because he was coming so very fast. Words telling a woman when and how to push are distracting, just let her listen to her body - it will tell her all she needs to know.
My question to you is do you think FER can occur in a medicalized birth, or for that matter in a hospital?