Amniotic fluid lecithin/sphingomyelin ratio changes related to centrifugal force.

Lecithin/sphingomyelin ratio (L/S ratio) in amniotic fluid has gained wide clinical acceptance as an index of fetal lung maturity. We determined L/S ratios of amniotic fluids centrifuged at various "g-forces." Our studies demonstrate that the L/S ratio value is highly dependent on the g-force used to prepare the fluid. We recommend standardization of the g-force, time, and temperature used in preparation of the amniotic fluid for L/S ratio determination.