Women in the second stage of labour instinctively bear down for short periods of four to six seconds. Most of these spontaneous bearing down efforts are accompanied by the release of air, with several breaths being taken between each effort. Conventional pushing techniques with sustained breath holding compromise fetal well being by reducing maternal arterial pressure and the oxygenation of maternal blood. Adequate progress may be made in labour, with the delivery of a healthy baby, when the management encourages spontaneous maternal efforts.
处于第二产程的女性会本能地短时间用力4至6秒。这些自发用力大多伴随着呼气,每次用力之间会呼吸几次。传统的屏气用力技术会降低产妇动脉压和母体血液的氧合作用,从而损害胎儿健康。当管理措施鼓励产妇自发用力时,分娩过程可能会取得足够进展,顺利产下健康婴儿。