[Fetal maturation and amniotic fluid levels of catecholamines and their metabolites]

Phosphatidylglycerol (PG), a phospholipid closely associated with fetal lung maturity, appears in the amniotic fluid (AF) of complicated pregnant women much earlier than it usually increases during uneventful pregnancy. In this study, AF PG levels, measured by an enzymatic method, were correlated with AF concentrations of catecholamines (CAT) and the deaminated metabolites of dopamine (3,4-dihydroxyphenylacetic acid; DOPAC) and norepinephrine (3,4-dihydroxyphenylglycol; DOPEG), all of which were determined by radioenzymatic assay. AF concentrations of CAT increased with the advance of gestation especially after 36 weeks of gestation, when clinically apparent fetal distress was not present. Three to four fold higher levels of DOPAC and DOPEG over their parent CAT were found in AF. Even prior to 37 weeks of gestation, high concentrations of CAT were found in the pregnancies complicated with fetal distress, and significant correlation was noted for PG versus dopamine (p less than 0.005), norepinephrine (p less than 0.05) epinephrine (p less than 0.02) and DOPEG (p less than 0.05), but not DOPAC. Such a correlation was not observed after 37 weeks of gestation. These findings suggest that fetal CAT plays a primary role in developing fetal lung maturation and that AF PG and CAT increase as a response to chronic distress, only before 37 weeks of gestation.