Amniotic fluid cortisol as an index of fetal lung maturity.

Amniotic fluid cortisol concentration was compared with lecithin/sphingomyelin ratio, gestational age, and eventual birth-weight in a large series of normal and high-risk human pregnancies in an effort to determine whether cortisol could be used as a reliable indicator of fetal maturity. It appears that when used alone amniotic fluid cortisol is of limited clinical value as an antepartum predictor of fetal respiratory status because of unacceptable percentages of false positive and false negative predictions. Whether amniotic fluid cortisol can be used as an adjunct in the evaluation of high-risk pregnancies with "transitional" L/S ratios remains to be explored.