Increase of fetal arterial blood temperature by reduction of umbilical blood flow in chronically instrumented fetal sheep.

The effect of reduced umbilical blood flow rate on fetal core temperature was investigated in five chronically instrumented fetal sheep (gestational age 124 days). On average, fetal-maternal temperature difference increased 0.13 +/- 0.02 degrees C when blood flow rate was decreased to about 1/3 of normal (248 +/- 69 ml min-1) for 30 min. The small temperature rise is the consequence of predominant heat dissipation through the placenta, and of diminished oxygen consumption.