Changes in energy metabolism substrates in biological fluids (venous and umbilical blood, urine, and amniotic fluid) were studied. Lactate concentrations were 2-4--fold increased in venous blood and 2-fold in umbilical blood. Urinary excretion of energy metabolism substrata was increased in women with gestosis. An increase of lactate concentration above 0.110 mmol/liter and of isocitrate concentration above 0.238 mmol/liter indicated fetal hypoxia.