The relationship of cortisol and cortisone to saturated lecithin concentration in ovine amniotic fluid and fetal lung liquid.

Cortisol and cortisone concentrations in ovine amniotic fluid and fetal lung liquid were analyzed with respect to gestational age and fetal lung maturation as reflected by saturated lecithin concentration. In amniotic fluid, the cortisol concentration rises as a function of gestational age while that of cortisone falls (P less than 0.001). The ratio of cortisol/cortisone is significantly related to gestational age (r=0.693, P less than 0.001), and shows an even stronger correlation with saturated lecithin concentration (r=0.832, P less than 0.001). When examined independently of gestational age, the correlation of the cortisol/cortisone ratio to saturated lecithin concentration remains highly significant (r=0.641, P less than 0.001). Similar findings were observed in fetal lung liquid, except that in this fluid both the saturated lecithin concentration and the ratio of cortisol/cortisone are significantly higher than simultaneously determined values in amniotic fluid. These observations provide further evidence that the process of fetal lung maturation is closely linked to the fetal hormonal milieu.