The Citrate Concentration in Adult and Fetal Plasma and in the Amniotic Fluid of the Guinea Pig

The mean concentration of citric acid in male and non-pregnant female adult guinea pig plasma was 0.308 ± 0.042 mM. Pregnant females with fetuses of 49–69 days gestational age had mean maternal and fetal plasma concentrations of 0.440 ± 0.011 and 0.217 ± 0.053 mM, respectively. Maternal and fetal values were not correlated. Neonates up to 96 h old had plasma citrate values similar to those in the fetus. The citrate concentration of the amniotic fluid was lower than that in fetal plasma and showed a negative correlation with conceptual age (p < 0.01).