Total lipids, cholesterol, phospholipids and inorganic phosphorus in the amniotic fluid of premature infants.

SUMMARY T~tal lipids, total cholesterol, phospholipids and inorganic phosphorus were determined in the amniotic fluid of 36 normal and 12 premature neonates. Total Iipids, phospho­ lipids and cholesterol were significantly decreased in the premature patients and the extent of decrease was more pronounced in patients who developed respiratory distress syndrome. On the other hand, inorganic phosphorus con­ tent of the amniotic fluid was within the normal range. S. Afr. med. l., 50, 1792 (1976). Interest in the composition of human ammotJc fluid re­ mained at a fairly low level from 1930 to 1945. Since then, the number of publjcations on this subject has increased remarkably. ln 1955 Hanon et al.' reviewed the literature on the composition of amniotic fluid. More recently com­ ponents of amniotic fluid were reported which related directly to fetal condition and maturity. Lipids are present in liquor amnii in steady concentra­ tions throughout normal pregnancy, phospholipids being the only ones that increase in concentration as term approaches.' Amniotic fluid contains about 60 mg/IOO ml total hpid.' Lipid analysis revealed the presence of phos­ pholipids, free cholesterol, cholesterol ester, monoglyce­ rides, diglycerides and triglycerides: Low total lipid and phospholipid concentrations have been demonstrated in hquor amnij from premature infants suffering from respi­ ratory distress syndrome (RDS) and in cases of anence­ phaly.' Recently, some investigators·-' have reported that amnio­ tic fluid phospholipids increase in the tillrd trimester of pregnancy. A relationship between amniotic fluid tri­ glyceride levels and fetal maturity has been found.' Pomerance et al: reported that cholesterol constitutes 25% - 33% of total lipids. They also reported an increase in amniotic fluid free cholesterol and unesterified fatty acids in cases of prolonged intra-uterine fetal death. Biezenski et al! determined the amounts and the per­ centage composition of the various hpid classes in the amniotic fluid to obtain a lipid profile at different stages of gestation. Amniotic fluid phospholipids and lecithin/ spillngomyelin ratios have been used as an index of fetal