Lactate and pyruvate as fetal metabolic substrates

Lactate and pyruvate concentration differences across the fetal umbilical circulation and the maternal uterine circulation were measured in a chronic sheep preparation. Significant gains in lactate in both the fetal and maternal circulations were observed. The lactate taken up by the fetus would account for 32% of fetal oxygen consumption if oxidized. There was no significant change in pyruvate concentration across the fetal umbilical circulation; however, pyruvate was gained by maternal uterine blood.