[Studies on fetal growth and functional development].

The characteristic process of fetal growth and the developments of cardiovascular function as well as fetal behaviors were studied. The size of fetal head, trunk, limbs, lung, liver and kidney were measured using ultrasonography and the process of fetal growth was analyzed with a computer. Fetal cardiovascular functions were assessed by M-mode echocardiography and pulsed Doppler ultrasound. Fetal behaviors such as rapid and slow eye movements, breathing movements and movements of head, trunk and limbs were simultaneously observed using three ultrasonic real-time scanners and the occurrence, the correlation and the cyclicity of each movement were analyzed with the specially programmed signal processor. The results were as follows: Fetal growth--The growth rate of fetuses (weight gain/day X fetal weight) was maximum at 25-30 weeks of gestation(W). Skeleton grew linearly until 30W, then decelerated the growing speed. The growth of organs such as lung, liver and kidney, which showed the same pattern as that of trunk, was accelerated after 26-27W. The thickening of skeletal muscle and the deposit of fat remarkably increased after 32W. The specific gravity of a fetus which was calculated according to the formulae for estimation of fetal weight and fetal volume showed maximum value at 32-34W. These results suggest that the growth of skeleton is accelerated first, organs next and muscle and fat deposit finally in a fetus.(ABSTRACT TRUNCATED AT 250 WORDS)