Heatflux from the fetus during delivery.

A new thermodynamic model for the fetus in utero is introduced. As the fetus is warmer than the mother, heat flows from the fetus to the maternal organism (i. e. uterine muscle, vagina). This heatflux was measured during delivery. The heatflux from the fetal head was 11 +/- 1.6 Watt/m2 (mean +/- SD). It was influenced by the maternal temperature (correlations statistically significant) in two births with pathological heart rate patterns in the cardiotocogram we observed a heatflux which deviated markedly from the norm. In conclusion, heatflux measurements could yield valuable information about the fetal metabolism and circulation of the fetomaternal unit, and could be applied as a additional method for fetal monitoring.