Serum vitamin B12 levels in parturients, in the intervillous space of the placenta and in full-term newborns and their interrelationships with folate levels.

Serum vitamin B12 levels were determined in a group of 51 parturients as well as in their babies and placentas. The results obtained showed that newborns had 2.3 times higher vitamin B12 levels than their mothers and that the concentrations of this vitamin in the intervillous space of the placenta was 1.3- and 3.2-fold those encountered in the blood of newborns and mothers, respectively. These findings indicate that vitamin B12 accumulation by the placenta may represent an important factor in providing sufficient amount of this essential nutrient to the fetus. The relationship between folate and vitamin B12 concentration in the maternal, fetal and placental sera was also investigated. The highly significant correlation coefficient encountered and significantly higher serum folate concentrations in the group of parturients who received vitamin B12 supplementation during pregnancy indicate a close metabolic interrelationship between vitamin B12 and folate.