I was recently searching for answers to a similar question.
What I came away with is that pushing position does matter in trying to avoid a tear, as does having a strong fer (fetal ejection reflex), which is best brought about when a birthing woman is left well alone, is comfortable, has privacy, warmth, etc.
Michel odent's answer to a similar question:
I recently suffered a 4th degree tear, 1 centimeter into the rectum, it was repaired by a surgeon. This began as a...