This position is only used in the U.S. routinely. And it doesn't use gravity. It is so the doctor can see what is happening. Her legs are in the air, her buttocks at the table's edge, her vagina totally exposed. As the ultimate symbolic inversion, it is ritually appropriate that this position be reserved for the peak transformational moments of the initiation experience - the birth itself.
Episiotomy is a surgical cut between the vagina and the anus.
It is used in case a woman tears, but women claim the stitches hurt worse than the tear. A tear in birth is the separation of weak tissue, an episiotomy is a straight cut through weak and strong tissue. Through episiotomies, physicians can deconstruct the vagina and reconstruct it in accord with technological values. Mostly because the obstetrical drugs make it difficult to push the baby out. Metal forceps are inserted inside the vagina to grasp the baby's head and are pulled.