Effect of prenatal T4 treatment in neonatal morbidity: preliminary findings

We report our experience with the use of intra-amniotic thyroxine to accelerate fetal maturation in preterm delivered infants. One hundred and fourteen infants who had received 500 micrograms of thyroxine weekly prenatally until an L/S ratio greater or equal to 2.0 was achieved, were compared to 113 premature infants who had not been given thyroxine or steroids prenatally. After stratification by weight, the relative incidence of respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), necrotizing enterocolitis (NEC) and intraventricular hemorrhage (IVH) were compared. A decrease in the incidence of RDS was observed in the infants with birth weight between 1000 and 1500 g who had received more than one dose of intra-amniotic thyroxine. No difference in the incidence of RDS was observed in infants with birth weight of less than 1000 g or over 1500 g. One dose of thyroxine had no effect in decreasing the incidence of RDS, PDA, NEC, and IVH in any of the groups. We conclude intra-amniotic thyroxine seems to decreases the incidence of RDS in very low birth weight infants.