The value of amniotic fluid lecithin/sphingomyelin determination in prediction of hyaline membrane disease.

246 samples of amniotic fluid were obtained from 245 women with normal or complicated pregnancy near or at parturition. The lecithin/sphingomyelin (L/S) ratio was determined and retrospectively correlated with the clinical course of the neonate. Ten neonates developed hyaline membrane disease (HMD). The highest L/S-ratio in this group was 1.82. Cesarean section was not associated with HMD if L/S-ratio indicated pulmonary maturity (L/S greater than 2). With the exception of children born by women with toxemia or chronic hypertensive disease, where no case of HMD appeared among nine infants children with birth weights less than 2000 g developed HMD in about 50% (6/11 cases). The results show that the L/S-ratio correlates well to the pulmonary maturity of the neonate. Determination of L/S-ratio is therefore of great importance in cases of high risk pregnancy or doubtful gestational age prior to induction or Cesarean section.