Amniotic Fluid Phospholipids In Early Gestation

In an attempt to explain poor clinical correlation between amniotic fluid lccitllin/sphingomyclin (L/S) ratio and development of respiratory distress syndrome when the ratio is low, a comparison was made of the phospholipid composition of amniotic fluids in early and late gestation. The results showed an increase in total phospholipid from 2.1 to 5.2 mg/100 ml. an increase of lecithin from 21.0 to 64.8% (0.44 nig to 2.92 mg/100 ml), and a decrease of sphingomyelin from 51.3 to 7.9% (1.07 mg to 0.35 mg/100 ml). Other phospholipids showed minor changes. Amniotic fluid sphingomyelin does not represent extrusion of lung surfactant and some clinical discrepancies might be avoided if, instead of L/S ratio, the percentage of lecithin in total phospholipids (L/PL ratio) is employed