There’s an odd non-medical reason why women give birth lying back

"He became frustrated by the obscured view of birth when it occurred on a birthing stool, and promoted the new reclining position," wrote sociologist Lauren Dundes in the American Journal of Public Health. He didn't make giving birth lying down a policy for his subjects but, regardless, it caught on. "The influence of the King's policy is unknown, although the behavior of royalty must have affected the populace to some degree," continues Ms Dundes. "Louis XIV's purported demand for change did coincide with the changing of the position and may well have been a contributing influence." As time went on and migration and colonisation moved people around the world, the technique became more and more common. So, rather than any new medical knowledge or developments, the change could well have come about because of one man's preference.