Background: The developmental changes of the umbilical cortisol levels in neonates at gestational age of 23-41 weeks were studied and the effect of antenatal steroid administration on the umbilical cortisol levels were examined.
Methods: Cortisol levels in the umbilical vein (UV) and the umbilical artery (UA) were studied in 35 neonates at the gestational age (GA) of 23-41 weeks with or without antenatal administration of corticosteroids. Serum cortisol concentrations were measured by the high performance liquid chromatography method.
Results: The correlation between cortisol levels in UV and birthweight (BW) was weak and negative in premature infants. UV cortisol levels in the neonates with antenatal corticosteroid were lower than those in the neonates without antenatal corticosteroid, but the relation was not significant. The developmental changes of UV cortisol levels were the same as those in Murphy's study (spontaneous-onset labor). The cortisol levels in UV and UA had a significantly positive correlation and both had almost equal concentrations. There were no correlations between cortisol levels in UV and placental weight, Apgar Score at 1 and 5 min.
Conclusions: In the neonates whose birthweight was less than 2000 g without antenatal corticosteroid, there was a negative correlation between cortisol levels in UV and BW but there was no correlation between cortisol levels in UV and GA. That the neonates with antenatal corticosteroid would have a suppressed adrenocortical function after birth could not be proved.