Abstractsby an ultrasensitive non-radioactive method on microplate and the TNFa protein expression by ELISA. Differences between the groups were determined by one way ANOVA (p<0.05). Results We observed a statistically significant decrease in the sPLA2 mRNA in the betamethasone (0.61) and dexamethasone (0.26) groups respect the control (1.05) group and a decrease in the sPLA2 activity in the betamethasone group (33.78) respect the control group (50.74). We observed a statistically significant decrease in the TNFa protein in the betamethasone group (472.61) respect the dexamethasone group (768.65). Conclusions Antenatal glucocorticoids inhibits the expression of sPLA2 through the reduction of TNFa in the lung of newborn rats. These potential beneficial effects are more evident in the group treated with antenatal betamethasone. Our studies also support the notion that betamethasone could be the drug of choice for treating pregnant women at risk of preterm delivery.