We report here changes in abundance of pulmonary cytosolic phospholipase A2 (cPLA2) and glucocorticoid receptor (GR) mRNAs and phospholipid (PL) fatty acids (FA) with gestational age, in either spontaneous or androstenedione-induced premature labor for 15 fetal rhesus monkeys and 1 neonate. Pulmonary RNA and lipids were extracted from the lungs of the rhesus monkeys, gestational ages ranging from 140 days to term. Northern hybridization analysis was performed for both cPLA2 and GR mRNAs. The results demonstrated the transcript of the cPLA2 constantly expressed and that of GR increased gradually in the lungs during the gestational stages studied. Phosphatidylcholine (PC), phosphatidylglycerol (PG) and phosphatidylinositol (PI) were separated by thin layer chromatography and the fatty acid composition in these PL was quantified by gas chromatography (GC). Regression analysis demonstrated that the expression of GR, mRNAs increased significantly with gestational age (P < 0.01). Furthermore, the level of GR mRNA is significantly correlated with that of cPLA2, with Pearson correlation coefficient of 0.83 (P < 0.01). The PC palmitate percentage increased significantly with gestational age (P < 0.01), while the PC unsaturation index and total polyunsaturated FA decreased during late gestation (P < 0.01). Changes in PG FA with gestational age were similar to those in PC, while PI FA did not change with gestational age. There was no effect of either spontaneous or induced labor on mRNA levels of cPLA2 and GR or the FA composition of pulmonary PL studied. We conclude that the pulmonary PL FA compositions are under developmental control.