Densitometry analysis showed that Hoxa5 to Hoxb6 ratio (A) gradually decreased throughout gestation in normal controls. However in NT-PH lungs, Hoxa5 to Hoxb6 ratio increased throughout gestation and was significantly increased in neonatal NT-PH lungs (*P<0.05, N=5, Mean ± SEM, Neo normal controls verses Neo NT-PH). On or before Gd19, Hoxb4/Hoxb6 ratio (B) was not different in normal verses NT-PH lungs but became significantly greater in neonatal NT-PH lungs (*P<0.05, N=5, Mean ± SEM, Neo normal controls verses Neo NT-PH). Normal lung Hoxa5 to Hoxb4 ratio (C) was unchanged across gestation but significantly elevated in Gd19 NT-PH lungs compared to normal controls (*P<0.05, N=5, Mean ± SEM, Gd19 Normal Controls verses Gd19 NT-PH).