Amniotic fluid elastolytic activity was assessed in a group of 120 women who delivered preterm infants and in 35 women who delivered at term. Amniotic fluid elastolytic activity decreases as pregnancy progresses. The lecithin-to-sphingomyelin (L/S) ratio in women's amniotic fluid was determined by the method developed by Gluck and associates [6] and elastolytic activity by that developed by Mehdi and associates. A significant negative correlation was found between the amniotic fluid L/S ratio and amniotic fluid elastolytic activity (r = −0.932; p<0.001).

The border value of elastolytic activity that indicates lung maturity (L/S ratio equal to or greater than 2) is 2.01 ± 0.05 mmol/min ml. In the amniotic elastolytic activity test, it is the value that differentiates mature from immature lungs. The amniotic fluid elastolytic activity test is characterized by high sensitivity (91.43%) and specificity (91.67%), high positive prognostic value (76.19%) and low negative prognostic value (2.65%). The test parameters do not therefore differ greatly from those of the Gluck test. Moreover, the amniotic fluid elastolytic activity test is cheaper and takes less time to perform.