The effect of antenatal betamethasone on cord blood concentrations of retinol-binding protein, transthyretin, transferrin, retinol, and vitamin E.
We assessed the effect of short-term (less than or equal to 1 week) and prolonged (greater than 1 week) exposure to antenatal betamethasone on umbilical cord serum concentrations of retinol-binding protein (serum t 1/2 = 12 h), transthyretin (t 1/2 = 2 days), transferrin (t 1/2 = 8 days), retinol (vitamin A), and vitamin E in appropriate-for-gestational-age preterm newborn infants of less than 36 weeks' gestation. A group of 30 infants whose mothers received a single course of betamethasone less than or equal to 1 week prior to delivery had significantly elevated mean retinol-binding protein and transthyretin but not transferrin concentrations when compared with a group of 30 gestational age- and birth weight-matched infants with no exposure to antenatal betamethasone. A group of eight infants whose mothers received multiple (more than two) weekly courses of betamethasone prior to delivery had significantly elevated mean serum concentrations of all three proteins when compared with eight gestational age- and weight-matched control infants with no betamethasone exposure. Serum retinol and vitamin E concentrations were measured in a group of 21 infants exposed to short-term prenatal betamethasone and were significantly greater than in a group of 21 control infants without steroid exposure. We conclude that antenatal steroids increase the umbilical cord serum concentrations of retinol-binding protein, transthyretin, transferrin, retinol, and vitamin E. The effect on the various serum proteins is dependent on the duration of exposure to steroids.