Relationship between cortisol levels in umbilical cord plasma and development of the respiratory distress syndrome in premature newborn infants.

The aim of this study was to determine whether there is a decrease in fetal cortisol levels associated with the respiratory distress syndrome (RDS). Eighteen newborn infants of less than 37 weeks' gestation who developed moderate to severe forms of RDS did have a significantly lower (P less than 0.02) mean cord plasma cortisol concentration at birth than that observed in 67 unaffected infants of similar gestational age; mean values +/- standard errors were 3.36 +/- 0.42 and 5.58 +/- 0.43 mug per 100 ml, respectively. However, whether or not RDS developed in neonates appeared to depend more upon the degree of prematurity (with a 71.5% incidence in gestations of less than 32 weeks compared to 17.1% in those of 32 to less than 37 weeks) than upon cortisol levels at delivery. Bood cortisol levels in the first days of life of four infants with RDS were considerably increased in comparison to those at birth. Mean cord plasma cortisol concentrations increased with duration of pregnancy, with the previously observed value for term infants (of 37 or more weeks) being approximately twice that for infants of less than 32 weeks' gestation. These findings appear to justify carefully controlled studied with antepartum glucocorticoid administration with the aim of reducing the incidence of RDS in premature newborn infants.