Measurement of "lamellar body phospholipid" in amniotic fluid as a method for assessing fetal lung maturity

A simple, rapid micro-method, suitable for use in a routine clinical laboratory, is described for isolating a surfactant fraction from 0.1 mL of human amniotic fluid and measuring its phospholipid content. We determined the phospholipid content of this fraction, referred to as "lamellar body phospholipid," in 451 samples of amniotic fluid collected within two days of delivery and related the data to the respiratory performance of the newborn in every case; 112 of the infants were delivered at 28-37 weeks gestation. The incidence of hyaline membrane disease was inversely related to the concentration of lamellar body phospholipid in the amniotic fluid. Eleven of 12 infants with lamellar body phospholipid values less than 25 mg/L and four of 44 infants with lamellar phospholipid values between 25 and 50 mg/L developed hyaline membrane disease or other serious respiratory problems possibly related to lung immaturity, whereas all of 395 infants with lamellar body phospholipid values of 50 mg/L or more were free from respiratory problems of this nature. The incidence of transient tachypnea was greatest when the lamellar body phospholipid value was between 25 and 50 mg/L, suggesting that this condition may be related to a degree of lung maturity.