Falling amniotic fluid palmitates in diabetic pregnancies

Palmitic acid levels were measured in samples of amniotic fluid obtained from 15 patients with diabetes. Seven patients had palmitate values which decreased at some time in pregnancy but only one of the infants developed respiratory distress. Eight of the 15 patients had final amniotic fluid palmitate values which were greater than 0.07 mmol/l and one infant developed respiratory distress. The other seven patients had final amniotic fluid palmitate values of 0.07 mmol/l or less and one of the infants developed respiratory distress. The significance of falling amniotic fluid palmitate values is discussed.     

Saturated phospholipids in amniotic fluid of normal and diabetic pregnancies

To assess fetal lung maturation in normal and diabetic pregnancies, the authors studied two phospholipids that are more specific for pulmonary surfactant than total phosphatidylcholine (lecithin), namely saturated phosphatidylcholine and phosphatidylglycerol. Results indicated that saturated phosphatidylcholine concentrations normally increase from 10 to 20 nmol/mL before 34 weeks to as high as 150 nmol/mL at term. Although the absolute concentration of saturated phosphatidylcholine could not be used to reliably identify pregnancies leading to respiratory distress syndrome, a saturated phosphatidylcholine level greater than 50% of total phosphatidylcholine was associated with satisfactory neonatal pulmonary function, whereas RDS often occurred in premature infants when less than half the phosphatidylcholine was saturated. Carefully regulated diabetic pregnancies at 36 to 42 weeks of gestation were not different from matched control subjects with respect to total phosphatidylcholine, its ratio to sphingomyelin, saturated phosphatidylcholine, or phosphatidylglycerol. Respiratory distress syndrome did not occur in any infant of the 40 diabetic mothers studied, nor were there any congenital anomalies or cases of symptomatic hypoglycemia.     

Deficient lung surfactant apoproteins in amniotic fluid with mature phospholipid profile from diabetic pregnancies

An enzyme-linked immunoassay to quantitate lung surfactant apoproteins (15 to 250 ng/ml) in human amniotic fluid is described. The immunoassay was used to quantify lung surfactant in 72 samples of amniotic fluid, for which lecithin/sphingomyelin (L/S) ratios, lecithin and phosphatidylglycerol concentrations, and foam stability indices were also available. The results obtained with the immunoassay were in general agreement with those of the other methods. Measurement of the apoproteins, however, may be a better predictor of fetal lung immaturity and of respiratory distress syndrome than the L/S ratio and the concentration of lecithin. This conclusion is based on the data obtained in the analyses of samples of amniotic fluid from four diabetic and five nondiabetic pregnancies, the infants of which developed respiratory distress. In all cases, the apoprotein concentration was less than 2.1 micrograms/ml, which indicated fetal lung immaturity. In six of these cases (one diabetic and five nondiabetic pregnancies), lung immaturity was also predicted on the basis of other tests. However, in three other cases of diabetic pregnancy, the L/S ratio and lecithin concentration falsely indicated lung maturity. In addition to its being an effective predictor of fetal lung maturity in diabetic, as well as nondiabetic, pregnancies, the immunoassay is better suited for clinical use because of its high specificity, sensitivity, and ease of performance.     

High-risk pregnancies and amniotic fluid isoamylase activity

A kinetic test (Phadebas) was employed to determine the isoamylase activity in 77 amniotic fluid samples taken from a total of 60 high-risk pregnancies at different gestational ages. It was ascertained that in high-risk pregnancies the s-type isoamylase level frequently deviates from the common scatter range of the respective week of gestation. The measured activity of the s-type isoamylase is subsequently set in relation to the pre- and postnatal state of the newborn. The findings support the assumption that in addition to ultrasound, hormone determination and cardiotocography, the estimation of s-type amylase activity in amniotic fluid may serve as an index for fetal well-being. A reduced secretion of the parotid gland as a result of fetal stress is discussed as a possible cause of the ascertained enzymatic changes in the amniotic fluid.     

Zinc and alpha-fetoprotein in amniotic fluid from early pregnancies with fetal malformations

Zinc and alpha-fetoprotein concentrations were quantitated in second-trimester amniotic fluid from 111 normal pregnancies and 29 pregnancies with various fetal malformations. The zinc level varied between 0.3 and 4.0 mumol/L (median 1.3) in the normal samples and between 1.8 and 17.9 mumol/L (median 5.0) in cases with malformations. The level was above 2.5 times the normal median in 23 of the 29 (79%) gestations with the malformations. Amniotic fluid zinc and alpha-fetoprotein levels showed a positive correlation (r = 0.78), and the alpha-fetoprotein level was elevated in all gestations with fetal disorders and elevated zinc levels, as well as in five of the six cases with fetal defects but normal zinc concentrations. The elevation of zinc was more marked than that of alpha-fetoprotein in three cases of fetal malformations. Five samples were false positive on alpha-fetoprotein assay but contained normal zinc levels. Removal of alpha-fetoprotein from amniotic fluid had no effect on the zinc concentration, indicating that zinc is not bound to amniotic fluid alpha-fetoprotein.     

Surfactant in the amniotic fluid and bromhexine metabolite VIII

The effect of metabolite VIII of bromhexine on surfactant content in the amniotic fluid was investigated in a double blind study. Administration of 100 and 200 mg NA-872 daily for 5 days to pregnant women ranging in gestational age from 196 to 243 days was not followed by a significant rise in the $\text{L}\text{S}$ ratio.     

Routine amniotic fluid alpha-fetoprotein measurement in 34,000 pregnancies

Of 34,000 initial amniotic fluid samples, 0.7% had an alpha-fetoprotein level greater than or equal to +3 SD above the mean. The risk of an open neural tube defect or other serious fetal abnormality was 60% when alpha-fetoprotein levels measured greater than or equal to +3 and 86% for levels greater than or equal to +5 SD. In this series there were 72 open neural tube defects, and all were identified. The true false positive rate was 0.9 per 10,000 cases screened.     

The amniotic fluid index in normal twin pregnancies

OBJECTIVE: We sought to investigate the amniotic fluid index for individual gestational sacs of twin pregnancies. STUDY DESIGN: Four hundred eighty-eight patients with normal diamniotic twins were examined between 14 and 40 weeks' gestation. The dividing membrane between twin fetuses was identified. An amniotic fluid index was then obtained for each gestational sac. RESULTS: The median amniotic fluid index in individual twin gestational sacs rises slowly from 14 to 16 weeks' gestation to 23 to 28 weeks' gestation and then gradually declines. The median amniotic fluid index values by gestational age for twin A and twin B are not statistically different. Although twin pregnancies have a slightly lower median amniotic fluid index value than singleton pregnancies, the difference is also not statistically significant. CONCLUSION: Individual amniotic fluid indices can be obtained in twin pregnancies, and the values are comparable with those of singleton gestations.     

Amniotic fluid phosphatidylglycerol in diabetic pregnancies

Despite L/S ratios indicating fetal lung maturity, respiratory distress continues to occur more frequently in infants of diabetic mothers. Amniotic fluid pulmonary phospholipids were studied in an attempt to understand the occurrence of false-positive L/S ratios in preterm diabetic pregnancies. Qualitative chromatographic assays of surfactant phosphatides revealed reduced or absent phosphatidylglycerol in diabetic amniotic fluid specimens between 34 and 37 weeks' gestation. Mean phosphatidylglycerol in 15 nondiabetic and 29 diabetic specimens was 16 and 4 per cent of total extracted pulmonary phospholipids (P < 0.001). Non-insulin-dependent diabetic pregnancies had lowest mean per cent phosphatidylglycerol. Respiratory distress occurred in six infants of diabetic mothers delivered preterm with L/S ratios of 2:1 or greater; phosphatidylglycerol was absent in five. The inclusion of phosphatidylglycerol in amniotic fluid phospholipid assessment may be an adjunctive index for fetal lung maturation in diabetic pregnancies.     

Immunoreactive oestrogens and progesterone in amniotic fluid in twin pregnancies

Amniotic fluid concentrations of immunoreactive oestrogens and progesterone were measured at the time of caesarean section in 32 twin pregnancies; 25 women had an elective section and seven were in labour at the time of operation. No significant differences between concentrations in the amniotic fluid of the first and second twin were found in respect of conjugated and unconjugated oestrone, oestradiol, oestriol, oestetrol and unconjugated progesterone either before or during labour. It is unlikely that changes in oestrogens or progesterone in the amniotic fluid are responsible for the selective changes seen in prostaglandins and fetal adrenal steroid during labour in the first twin.     

Immunoreactive oestrogens and progesterone in amniotic fluid in twin pregnancies

Summary. Amniotic fluid concentrations of immunoreactive oestrogens and progesterone were measured at the time of caesarean section in 32 twin pregnancies; 25 women had an elective section and seven were in labour at the time of operation. No significant differences between concentrations in the amniotic fluid of the first and second twin were found in respect of conjugated and unconjugated oestrone, oestradiol, oestriol, oestetrol and unconjugated progesterone either before or during labour. It is unlikely that changes in oestrogens or progesterone in the amniotic fluid are responsible for the selective changes seen in prostaglandins and fetal adrenal steroid during labour in the first twin.     

Insulin levels in amniotic fluid of normal and abnormal pregnancies

The normal level of insulin in amniotic fluid between the 13th and 42nd weeks of pregnancy was determined by means of 988 single analyses in individual healthy women. Insulin passes into the amniotic fluid via the fetal urine, and its level does not depend on fetal gender. Between the 13th and 25th weeks of gestation, the insulin level increases by an average of 1.3 to 5.1 microU/ml. From the 27th to the 42nd weeks, an increase of 6 to 9.1 microU/ml is observed. In the same period, the 97th percentile rises from 11.2 to 18 microU/ml. In 543 patients with pregnancy disorders, lower levels of insulin in amniotic fluid were observed in intrauterine fetal death, placental insufficiency, fetal growth retardation, and malformations. Elevated levels of insulin were observed in rhesus disease. In the treatment of pregnant women with betamimetics and glucocorticoids, the mean amniotic fluid insulin level rose to more than double the normal values.     

Fetal lung maturity in diabetic pregnancies: relation among amniotic fluid insulin, prolactin, and lecithin

Insulin, prolactin, and lecithin phosphorus levels were measured in 97, 62, and 44 amniotic fluid samples from third trimester normal, gestational diabetic, and insulin-dependent diabetic patients, respectively. There was no difference in lecithin phosphorus concentration (index of fetal lung maturity) among the three groups. The amniotic fluid insulin level was significantly higher in insulin-dependent diabetic patients, whereas there was no difference in amniotic fluid prolactin levels among the groups. Correlations of amniotic fluid prolactin levels with both lecithin phosphorus and insulin levels were not statistically significant in any of the groups. This is probably because amniotic fluid prolactin is decidual, rather than fetal, in origin. Even though amniotic fluid insulin levels, which reflect fetal levels, were significantly higher in insulin-dependent diabetic patients, there was no difference in the amniotic fluid lecithin phosphorus concentration in diabetic pregnancies compared with that in normal pregnancies. Moreover, there was a positive, and not a negative, correlation between amniotic fluid insulin and amniotic fluid lecithin phosphorus levels in diabetic pregnancies. These results do not support the theory that fetal hyperinsulinemia results in delayed pulmonic maturation in diabetic pregnancies.     

Amino acid variations in amniotic fluid and maternal plasma from Rh-sensitized pregnancies. II

Amino acids were quantitated by ion-exchange chromatography in amniotic fluid and maternal plasma from Rh-sensitized pregnancies. Twenty-four patients of 34 to 40 weeks' gestation were studied, and results were compared to those in normal pregnancy. Significant differences were found for amino acid concentrations in amniotic fluid and maternal plasma from those patients in whom fetal death occurred. When the fetus survived, amino acid levels were similar to normal levels. In particular, it was noted that proline levels were markedly elevated in the amniotic fluid of patients in whom fetal death occurred (p < 0.001). From this preliminary work arises the interesting possibility that an increased amniotic fluid versus maternal plasma proline level may be of diagnostic assistance in severe Rh disease.