The metabolic and endocrine milieu of the human fetus at 18-21 weeks of gestation. II. Blood glucose, lactate, pyruvate and ketone body concentrations.

Blood levels of glucose, lactate, pyruvate and total ketone bodies were measured in 16 conscious mothers and their minimally stressed fetuses at 18-21 weeks gestation. Blood samples were taken from the maternal antecubital vein and from the fetal umbilical vein and artery during fetoscopy prior to termination of pregnancy. The mean concentrations of blood glucose, lactate and pyruvate were similar in maternal and fetal venous blood; no significant difference was found between the fetal umbilical artery and vein concentrations. Maternal total blood ketone body levels were significantly higher than fetal levels with no detectable umbilical venous arterial concentration difference. There was a significant inverse relationship between the umbilical artery levels and the umbilical venous-arterial concentration differences for blood glucose and lactate.