outlet contracture, an abnormally small pelvic outlet. It may be anteroposterior or transverse and is of significance in childbirth because it may impede or prevent passage of a baby through the birth canal. Anteroposterior contracture caused by fixation of the coccyx may sometimes be overcome by the force of labor, freeing the bones and allowing them to move back. Significant narrowing of the space between the ischial tuberosities is unlikely to be overcome and is most commonly associated with a heavy, android type of pelvis.
