A comparison between the lecithin/sphingomyelin ratio and the Nile blue sulphate test in the estimation of fetal maturity.

Functional fetal maturity was assessed in 72 patients by measuring in amniotic fluid the lecithin/sphingomyelin ratio and the differential cell count. The correlation between these two tests is presented. Only one fetus with a lecithin/sphingomyelin ratio of 2 or more developed the respiratory distress syndrome after delivery: that was the child of a diabetic mother. The technical limitations of the lecithin/sphingomyelin ratio meant that it could not be measured in 12% of samples obtained.