Amniotic fluid lecithin/sphingomyelin ratio in high risk pregnancy.

The amniotic fluid lecithin/sphingomyelin (L/S) ratio from 128 cases of high risk pregnancies were measured by using high performance liquid chromatography (HPLC). The L/S ratio was found to be increased in patients with pre-eclampsia, hypertension, intrauterine growth retardation (IUGR), prolonged rupture of membranes (PROM), and twin gestation, but decreased in patients with diabetes from gestational diabetes to class C. In patients with placenta previa, the L/S ratio was not affected.