Before revision: The German obstetrician Mr Welheim Horkel, when visiting a medical mission in the mid-1980s, learned that African tribes used gourds of increasing sizes to stretch the perineum to avoid damage of childbirth.
After revision: The German obstetrician Mr Welheim Horkel, when visiting a medical mission in the mid-1980s, learned that African tribes used gourds of increasing sizes to stretch the perineum , to avoid tearing during childbirth.