Serum and red blood cell folate levels in parturients, in the intervillous space of the placenta and in full-term newborns.

Folates, essential nutrients for man, are especially important during gestation. Serum and red blood cell folate levels were measured in 51 parturients and in their respective placentas and concepts, with the objective to further elucidate the mechanisms of folate transfer from mother to fetus. The interrelationships between the three compartments with respect to folate levels were also studied (Tab. I). Serum and red blood cell folates were measured by radioimmunoassay in samples of venous blood from the mother, from the intervillous space of the placenta, and from the umbilical cord. Higher folate levels were detected in newborns than in their mothers both in serum (3.9 times) and red blood cells (2.3 times). Serum folate levels were higher in the intervillous space of the placenta than in newborns (1.3 times) or mothers (4.5 times) Fig. 1, 2). These data suggest that the placenta concentrates folates, thus offering high concentrations of this vitamin to the fetus. It is possible that folate-binding proteins existing in the placenta participate in the mechanism of folate concentration in this organ. However, despite the existence of a transfer mechanism that benefits the fetus, a significant positive correlation was observed between serum folate levels of mothers, newborns and placentas.