Assumption: Medical personnel help women give birth by telling them when to push and counting for them.
In this study, medical personnel stopped several practices that have become standard in our hospitals. They stopped telling women when and how long to push and allowed women to push in the position of their choice (usually not on their backs since this is less comfortable for most women). During the study, the incidence of third and fourth degree tears decreased significantly.
This isn’t surprising to many women who have given birth. The body’s natural urges tend to guide Mom better than a generic formula. I’d like to see a study of these same women in five or ten years and compare to a control group in assessing lasting perineal trauma. (i.e. peeing on yourself when you sneeze or jump) I suspect there would be a significant difference there too.