A condition that may occur during the third stage of labor in which a relaxed uterus is turned inside out, causing the internal surface to protrude into the vagina. Uterine inversion most commonly is caused by traction on an umbilical cord attached to a yet-adherent placenta or to application of forceful fundal pressure to empty the uterus. It is accompanied by profound maternal blood loss if normal anatomical position is not restored immediately. Inversion also can occur during the fourth stage of labor if forceful fundal massage is applied to an uncontracted uterus without support of the lower uterine segment.