title: An explanation for the correlation between amniotic fluid optical density and the lecithin/sphingomyelin ratio.
mesh_terms: D000653:Amniotic Fluid / Q000032:analysis*; D003720:Densitometry; D005260:Female; D006801:Humans; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D013109:Sphingomyelins / Q000032:analysis*
chemical_list: D010713:Phosphatidylcholines; D013109:Sphingomyelins