title: A problem concerning determination of the lecithin/sphingomyelin ratio of amniotic fluid.
mesh_terms: D000653:Amniotic Fluid / Q000032:analysis*; D005260:Female; D006801:Humans; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D013109:Sphingomyelins / Q000032:analysis*
chemical_list: D010713:Phosphatidylcholines; D013109:Sphingomyelins