Nitrous oxide has a lot going for it. It merely blunts pain, but it also lets a laboring woman walk, perch on a birthing ball, whatever. It’s comparatively cheap, and it’s fast-acting, offering relief in less than a minute. Perhaps most key from midwives’ point of view, it is easily administered by the laboring woman herself. She grabs the mask when she knows a contraction is coming. She stops as the contraction ends. In other words, she is empowered to manage her own pain.