THE INTRAUTERINE TURNOVER OF THIAMIN IN PRETERM AND FULL-TERM INFANTS

In thirteen preterm infants, 45 full-term infants, and their mothers t hiamin M-as analyzed in plasma from maternal veins, umbilical arteries , umbilical veins, and placental tissue. The blood flow in the umbilic al veins was determined by pulsed Doppler ultrasonography!: Thiamin-de pendent transketolase was measured in erythrocytes from full-term infa nts and their mothers. - Plasma thiamin concentrations in umbilical ve ins from preterm infants (227.0 +/- 85.0 nmol/L) and full-term infants (121.3 +/- 103.3 nmol/L) were seven times greater than maternal conce ntrations (p < 0.005). Maternal and umbilical thiamin concentrations w ere lower in the full-term group compared to the preterm group (p < 0. 05). Arteriovenous concentration gradients were not feasible. The bloo d flow in the umbilical veins was higher in full-term compared to pret erm infants (p < 0.05). However, intrauterine thiamin supply (plasma t hiamin concentration rimes umbilical plasma flow) and placental thiami n concentrations were not different between preterm and full-term infa nts. Thiamin saturation of transketolase was greater in fetal than in maternal erythrocytes (p < 0.005); severe thiamin deficiency was nor o bserved. Our findings suggest that thiamin turnover is similar in earl y and late pregnancy. Fetal tissue uptake of thiamin is not substantia l, Transketolase activities suggest that thiamin status is sufficient even in late pregnancy.