Evaluation of fetal lung maturity in case of diabetic pregnancy by determination of the L/S ratio in the tracheal aspirate

Lung maturity of the newborn may be determined during pregnancy by means of the L/S ratio or the foam test in the amniotic fluid. Recently, the L/S ratio and foam test have been applied to the infant's tracheal aspirate right after delivery and have been found to be reliable parameters for prediction of respiratory distress syndrome (RDS). Nevertheless, while the incidence of RDS in newborn babies of diabetic mothers is increasing, the prediction of this syndrome has been found to be somewhat less reliable in diabetic pregnancies. A case is reported of a baby of a diabetic mother in whom the L/S ratio and the foam test in the tracheal aspirate demonstrated that, as in the amniotic fluid, these tests are unreliable in evaluating fetal lung maturity in diabetic pregnancies.