The pattern of change in the lecithin/sphingomyelin ratio in patients with preterm premature rupture of membranes between 24 and 34 weeks' gestation.

Objective: To report the pattern of change in the lecithin/sphingomyelin (L/S) ratio in patients with preterm premature rupture of membranes (PPROM) between 24 and 34 weeks' gestation.

Study Design: L/S was determined prospectively using transvaginally and transabdominally collected amniotic fluid from patients with PPROM between 24 and 34 weeks' gestation. Samples were collected prospectively on admission and every 48 to 96 hours until L/S was > or =2.