Fetal lung maturation: amniotic fluid catecholamines, phospholipids, and cortisol.

The identification of beta-adrenergic receptors in the fetal lung led us to investigate amniotic fluid catecholamine levels in relation to other indices of fetal pulmonary maturity in late pregnancies (n = 62). Significant correlations were found between the percentage of phosphatidylglycerol and concentrations of norepinephrine (r = 0.44, p less than 0.001), its intraneuronal deaminated metabolite 3,4-dihydroxyphenylglycerol (DOPEG; r = 0.74, p less than 0.0001), epinephrine (4 = 0.43, p less than 0.001), and cortisol (r = 0.78, p less than 0.001). Highly significant elevations of these substances were noted with accelerated pulmonary maturation. Lecithin/sphingomyelin (L/S) ratios showed a significant correlation with cortisol levels (r = 0.50, p less than 0.001); however, significant associations between L/S ratios and catecholamine levels were found only when complicated pregnancies were excluded. These findings support the contention that fetal contention that fetal adrenergic activity participates in the process of pulmonary maturation.