The lecithin/sphingomyelin ratio in decline.
D000653:Amniotic Fluid / Q000032:analysis*; D004739:England; D005260:Female; D005325:Fetal Organ Maturity; D006801:Humans; D008168:Lung / Q000196:embryology; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000639:trends*; D013109:Sphingomyelins / Q000032:analysis*
D010713:Phosphatidylcholines; D013109:Sphingomyelins