低体重儿的死亡原因以新生儿呼吸窘迫综合征(RDS)最为常见,RDS的发病原因与肺泡不成熟及缺乏能使肺泡充分扩张的肺泡表面活性物质有关。近年来,认为即使肺泡构造已完善,若缺乏肺表面活性物质也不能进行充分的呼吸。这种肺表面活性物质是磷脂质和蛋白质的复合体,在磷脂质中起表面活性作用的是饱和的亚磷脂,它在胎儿肺泡Ⅱ型细胞内合成并向肺泡腔分泌而出现于羊水中。因此许多人试验在出生前用羊水分析来诊断胎儿肺成熟度,自Gluck等(1971)测定羊水中卵磷脂与鞘磷脂之比以来,又进行许多研究,如Nelson测定羊水中磷脂质量及卵磷脂量,藤原等以蔗糖密度梯 The causes of death in low birth weight infants are most common in neonatal respiratory distress syndrome (RDS), and the pathogenesis of RDS is related to immature alveoli and the lack of alveolar surfactant that can fully expand the alveoli. In recent years, it has been considered that adequate respiration can not be achieved even in the absence of pulmonary surfactant even though the alveolar structure is well established. This pulmonary surfactant is a complex of phospholipids and proteins that are surface-active in phospholipids and are saturated phospholipids that are synthesized in fetal alveolar type II cells and secreted into the alveolar space in amniotic fluid. Therefore, many people test the use of amniotic fluid analysis to diagnose fetal lung maturity prior to birth. Since Gluck et al. (1971) determined the ratio of lecithin to sphingomyelin in amniotic fluid, there have been many studies, such as Nelson’s determination of phospholipid mass in amniotic fluid and lecithin Amount, Fujiwara to sucrose density ladder