Body size and thermic exchanges in the human fetus.

On the ground of data obtained in previous works, the trend of the various morphometric parameters, in particular of the body surface area/volume ratio (S/V), and the physio-pathological aspects of this problem, during the human fetal growth was analysed. The S/V ratio, that shows a rapid fall (92% of the initial value) during the 2nd and the 3rd months of development and later on trends to be more and more constant, is the expression of the changes of the shape, as well as the size of the fetus. These changes occur in the period of transition from embryonic to the fetal stage of development and affect the embryo-fetal termic stability, according to extent of the skin surface with respect to the unit of volume. Comparing these observations to the data of the literature, the Authors points out the significance of the S/V value in the radiant heat exchanges between the fetus and the developmental environment, and proposes this ratio for a parameter of the normal fetal growth.