Fetal movement and fetal presentation.

Fetal movements were analyzed by means of ultrasonography in an attempt to clarify the causative factor of frank breech presentation. Fetal posture, position, presentation and movements, as well as posture of the extremities and the volume of amniotic cavity were analyzed by ultrasonography in 112 fetuses ranging from 12 to 42 weeks of gestation. There existed three different fetal states: inactivity; slow sporadic movements without changes of presentations; active whole body movements with changes of presentations. It appears likely that version of fetal presentation from breech to cephalic occurs as the fetus tries to accommodate itself to the shape of the uterus during the state of active whole body movements, and the frank breech presentation of the fetus might result when the whole body movements are weak or absent.