Fetal motor activity and spine development.

The Authors, on the basis of previous data obtained by ultrasonography, analysed more closely the quantitative and qualitative correlations between movements and spine development in the human fetus. The bending angles of cervical lordosis and thoracic kyphosis showed a trend directly and inversely proportional, respectively, to the trend of the overall motility of the fetus, measured as the percentage of time employed by the fetus in motor activity. The trend of the lumbo-sacral angle, that appears later, seemed to be less related to the motor behaviour of the fetus, while the bending angle of lumbar lordosis increases very rapidly when also the fetal motility shows an increase at 25-30 weeks. The significance that the developmental stages and the actions of the muscles involved in early fetal motility, and particularly in spine movements, have in the ossification and in the postural attitude of the axial skeleton, was finally discussed.