Reliability of lecithin/sphingomyelin ratios in diabetic pregnancy.

Diabetic pregnancy is said to be associated with a delay in pulmonary maturity and significant false-positive rates for the lecithin/sphingomyelin (L:S) ratio. Lecithin/sphingomyelin ratios without routine estimation of phosphatidylglycerol in the management of 102 insulin-dependent diabetics were analyzed to assess whether or not these ratios were mature at 37 weeks and whether or not the method used was reliable. Only two of 102 (1.9%) values were reported at less than 2 to 1 from amniocentesis at 37 weeks' gestation. The incidence of respiratory distress syndrome was zero. The authors concluded that the L:S ratio measured by the method used, is a reliable predictor of lung maturity in diabetic pregnancy and that with strict glucose homeostasis, normal pulmonary maturation occurs by 37 weeks' gestation in diabetic pregnancy.