Effects of intrauterine growth restriction on lung liquid dynamics and lung development in fetal sheep

OBJECTIVE: The aim of this study was to determine the effects of intrauteri ne growth restriction on fetal lung liquid and lung development. STUDY DESIGN: Intrauterine growth restriction was induced in 7 fetal sheep from 120 to 140 days' gestation (term, approximately 147 days' gestation) b y umbilicoplacental embolization. We used 6 control fetuses. Volumes and pr oduction rates of fetal lung liquid were measured, and lungs were removed p ost mortem (140 days' gestation) for analysis of concentrations of deoxyrib onucleic acid, protein, and messenger ribonucleic acid for surfactant prote ins A, B, and C. RESULTS: Umbilicoplacental embolization induced fetal hypoxemia, hypoglycem ia, and intrauterine growth restriction. At 140 days' gestation lung weight was reduced by 34%, and the fetal lung liquid production rate (15.9 +/- 1. 8 mL/h for intrauterine growth restriction vs 24.8 +/- 3.9 mL/h for control ) and volume (110.9 +/- 16.3 mt for intrauterine growth restriction vs 178. 1 +/- 11.9 mt for control) were reduced in the intrauterine growth restrict ion group. After adjustment for body weight, however, values were not diffe rent from those in the control group. Pulmonary deoxyribonucleic acid and p lasma cortisol concentrations were elevated by intrauterine growth restrict ion, but levels of messenger ribonucleic acid for surfactant proteins were unchanged. CONCLUSION: In intrauterine growth restriction, lung liquid and lung growth were proportionate to body weight, and surfactant protein expression was u naffected. Alterations in lung deoxyribonucleic acid concentrations suggest that the lungs may be structurally immature.