RELATIONSHIP BETWEEN AMNIOTIC-FLUID AND MATERNAL BLOOD NUTRIENT LEVELS

To study the relationships between amniotic fluid and maternal blood n utrient concentrations, we obtained amniotic fluid and blood samples s imultaneously from 76 pregnant women at around 17 weeks gestation. Fol ate and vitamin B-12 levels were measured by microbiological assay and radioassay, respectively, and zinc, copper and iron levels by atomic absorption spectrophotometry. Mean concentrations of plasma and red bl ood cell (RBC) folate and plasma copper of the pregnant women were 38 (+/- 1, SD), 1,501 (+/- 374) nmol/L, and 32.7 (+/- 4.8) mu mol/L, resp ectively, all of which were higher than those of healthy non-pregnant controls (p < 0.001). Mean concentrations of plasma vitamin B-12,zinc and iron levels and RBC zinc were 320 (+/- 130) pmol/L, 12.2 (+/- 2.3) , 21.7 (+/- 6.1) and 177 (+/- 30) mu mol/L and these were similar to t hose of non-pregnant controls. Amniotic fluid folate, zinc, copper and iron concentrations were 21 (+/- 13) nmol/L, 1.4 (+/- 0.6), 1.7 (+/- 0.6) and 6.8 (+/- 2.1) mu mol/L, respectively, which were significantl y lower than plasma levels (p < 0.001). However, this relationship was reversed for vitamin B-12 (650 +/- 420 pmol/L). Significant correlati ons were found between amniotic fluid and maternal plasma and RBC for folate, and between amniotic fluid and maternal plasma for vitamin B-1 2 (p < 0.001). No such correlations were observed for zinc, copper and iron. There was no correlation between amniotic fluid and/or blood nu trient concentrations and pregnancy outcome including birth weight of infants.