Phospholipids and creatinine in amniotic fluid in relation to gestational age. II. Complicated pregnancy

176 samples of amniotic fluid were obtained by abdominal amniocentesis from 69 women with complicated pregnancies (toxemia, diabetes mellitus or rhesus isoimmunization) in the 27th-43rd week of pregnancy. The concentration of creatinine (172 cases), the ratio of lecithin/sphingomyelin (L/S-ratio, 155 cases) and phospholipid phosphorus (155 cases) were determined and related to gestational age. The results were compared with normal pregnancy. The mean level of creatinine in toxemia was significantly higher from the 32nd week till term (p less than 0.05) and the L/S-ratio was significantly higher (p less than 0.05) in the 34th-35th week compared with normal pregnancy. Creatinine concentration was significantly elevated in diabetic pregnancy in the 36th-37th week (p less than 0.05). Creatinine concentration tended to be low in Rh-isoimmunization. A creatinine concentration greater than or equal to 1.8 mg% and a L/S-ration greater than or equal to 2.25 always corresponded to a gestational age greater than or equal to 35th week. To get increased precision in estimating gestational age in complicated as well as in normal pregnancy the determination of both creatinine concentration and L/S-ratio in amniotic fluid is recommended.