头先露时胎头不以枕前位俯屈通过产道称为胎头位置异常。胎头位置异常有胎方位衔接异常如胎头高直位,有内旋转发生阻碍如持续性枕后位及枕横位,有胎头姿势异常,如胎头仰伸呈前顶先露、额先露及面先露,胎头侧屈呈前不均倾位。胎头位置异常使胎头下降 The first head exposed when the fetal head is not the anterior occipital flexion through the birth canal called the fetal head position abnormalities. An abnormal fetal head position Abnormal fetal orientation such as abnormal fetal head position is high, there is an impediment to rotation Such as persistent occiput posterior position and occipital transverse position, fetal head posture abnormalities, First dew and face first dew, fetal head flexion was uneven before the dumping. Abnormal fetal head position fetal head down