INTRAUTERINE VITAMIN-B-2 UPTAKE OF PRETERM AND FULL-TERM INFANTS

Intrauterine uptake of vitamin B-2 in preterm and full-term infants wa s examined. Factors of influence on vitamin supply were considered. Fo rty-four women and their infants were included in the study. Fetal vit amin uptake was calculated as arteriovenous concentration gradient in cord plasma times umbilical plasma flow. Concentration of vitamin B-2 (free riboflavin and flavocoenzymes) was determined by high performanc e liquid chromatography of placental tissue and blood plasma (maternal vein, umbilical artery, umbilical vein). Flavocoenzymes were analyzed as flavin mononucleotide after acid hydrolysis of flavin adenine dinu cleotide. Umbilical plasma flow was measured using pulsed Doppler sono graphy. Both free riboflavin and flavocoenzymes were transferred from the maternal plasma to the umbilical vein, but only free riboflavin wa s accumulated (similar to 1:4 for preterm and full-term infants, respe ctively). Flavocoenzyme concentration was higher in the umbilical vein than in the umbilical artery (p < 0.05). This indicated a median upta ke of flavocoenzymes of 1.5 nmol/min . kg in preterm infants and 0.4 n mol/min . kg in full-term infants (preterm versus full-term, p < 0.01) . Fetal vitamin supply depended on umbilical plasma flow and on matern al vitamin status (the latter was shown only in full-term infants). No dependence on placental vitamin concentration was observed (p > 0.05) . Concentration of free riboflavin was higher in umbilical artery than in umbilical vein (p < 0.05). This indicated a release of free ribofl avin from fetal tissues independent of gestational age (0.4 nmol/min . kg, preterm; 0.2 nmol/min . kg, full-term; p > 0.05).