Transient hypothyroxinemia in neonates with birth asphyxia delivered by emergency cesarean section.

The aim of this study was to evaluate the effects of prenatal asphyxia on perinatal thyroid function by measuring the levels of serum T4, FT4, T3, rT3, TSH and TBG in twenty-seven asphyxiated full-term infants delivered by emergency cesarean section, at birth and on the 5th day of age. All the babies had a one-minute Apgar score of less than 6 and body weight from 3 to 4.6 kg. The control group consisted of 30 healthy neonates which were delivered by elective cesarean section. The mean values of T4 and FT4 observed in the cord blood of the asphyxiated neonates were significantly lower compared to the matched controls, while there were no differences in concentrations of T3, rT3, TSH and TBG. At five days of life, serum concentrations of T4 and FT4 became normal. These results demonstrate the existence of transient hypothyroxinemia at birth in hypoxic babies delivered by emergency cesarean section.