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PubMed1995

Acute maternal hydration in third-trimester oligohydramnios: effects on amniotic fluid volume, uteroplacental perfusion, and fetal blood flow and urine output.

OBJECTIVE: Our purpose was to determine whether acute maternal hydration in pregnancies with third-trimester oligohydramnios (1) increases amniotic fluid index and hourly fetal urine production rate and (2) alters uteroplacental perfusion and fetal blood flow. STUDY DESIGN: Ten women with third-trimester oligohydramnios (amniotic fluid index < or = 5 cm) and 10 controls with normal amniotic fluid volume (amniotic fluid index > 7 cm) were prospectively recruited for this study. Maternal plasma and urine osmolality, amniotic fluid index, hourly fetal urine production rate, and Doppler flow velocimetry of maternal uterine artery and fetal umbilical, descending aorta, middle cerebral, and renal arteries were determined before and after oral hydration by having the patient drink 2 L of water over 2 hours. RESULTS: There was a significant reduction in maternal plasma (p < 0.05) and urine osmolality (p < 0.0001) in both groups after short-term oral hydration. Hydration increased amniotic fluid volume in women with oligohydramnios (mean change in amniotic fluid index 3.2 cm, 95% confidence intervals 1.1 to 5.3; p < 0.02) but not in those with normal amniotic fluid volume (mean change in amniotic fluid index -2.0, 95% confidence intervals -4.1 to +0.2). The hourly fetal urine production rate, however, did not increase in either group (mean change in hourly fetal urine production rate 3.5 ml/hr, 95% confidence intervals -11.7 to +18.7 and -6.8 ml/hr, 95% confidence intervals -2.9 to -10.7, respectively). Hydration was associated with an increase in uterine artery mean velocity in the oligohydramnios group (mean change in mean velocity 16.7 cm/sec, 95% confidence intervals 8.0 to 25.3; p < 0.006) but not in controls (mean change in mean velocity 1.2 cm/sec, 95% confidence intervals -19.7 to +22.1). There was no change in pulsatility index or in velocity in any of the fetal vessels studied in either group. CONCLUSIONS: Short-term maternal oral hydration increases the amniotic fluid index in women with third-trimester oligohydramnios. Although the mechanism for this effect remains unclear, it could not be accounted for by fetal urination in this study but instead was associated with improved uteroplacental perfusion.

Amniotic Fluid↗
PubMed1997

Amniotic fluid interleukin-10 (IL-10) concentrations during pregnancy and with labor.

To determine if amniotic fluid interleukin-10 (IL-10) concentrations are elevated in women with labor, either at term or preterm, and in the setting of infection-associated preterm labor, amniotic fluid samples were collected from women: (1) at term, not in labor (n = 42); at term, in labor (n = 56), preterm contractions, undelivered within 1 week (n = 22), and preterm labor, delivered within 1 week (n = 31). IL-10 concentrations were assayed in each sample via ELISA (Pharmingen, San Diego, CA). In a subsequent analysis, 8 women with preterm labor associated with chorioamnionitis were matched for gestational age with women experiencing preterm contractions (undelivered within 7 days) and preterm labor (delivered within 7 days) and amniotic fluid IL-10 concentrations compared. Approximately 40-70% of amniotic fluid samples obtained from women in each group had detectable IL-10. However, there were no significant differences in amniotic fluid IL-10 concentrations among the patients. While 1 of 8 patients with chorioamnionitis had amniotic fluid IL-10 concentrations greater than 300 pg/ml, there were no statistically significant differences among the matched samples. Amniotic fluid IL-10 concentrations were not elevated in women with term labor, preterm labor, or chorioamnionitis. This finding contrasts with the elevated concentrations of pro-inflammatory cytokines and chemokines such as interleukin-1, tumor necrosis factor-alpha, IL-6, IL-8, MIP-1 alpha, and GRO alpha reported in previous studies. Because we did not detect elevations of the key anti-inflammatory cytokine IL-10 in amniotic fluid of women with infection-associated preterm labor, we suggest that anti-inflammatory processes in this setting may be attenuated.

Adult↗
PubMed1987

The physical characteristics and enzymatic modification of fetal intestinal alkaline phosphatase in amniotic fluid.

The predominant form of alkaline phosphatase in amniotic fluid at 16 to 18 weeks gestation has the inhibition characteristics of the isoenzymes from adult and fetal small intestine. These characteristics are shared by an alkaline phosphatase of presumed intestinal origin occasionally found in the sera of premature neonates. However, in contrast to the rapid anodal migration of the latter enzyme, amniotic fluid phosphatase is of low electrophoretic mobility in polyacrylamide gel, and it has a high molecular weight. Digestion of amniotic fluid with bromelain produces a rapidly-migrating active enzyme form, with a molecular weight of about 135,000, compared with 145,000 for the fetal intestinal phosphatase in serum. The bromelain-treated amniotic fluid phosphatase is similar in size to a Kasahara isoenzyme in the serum of a cancer patient, which is itself thought to result from re-expression of a fetal intestinal phosphatase gene.

Adult↗
PubMed2001

Amniotic fluid matrix metalloproteinase-8 indicates intra-amniotic infection.

OBJECTIVE: This study was undertaken to determine whether matrix metalloproteinase-8, which is produced by neutrophils, is a useful marker for the detection of intra-amniotic infection. STUDY DESIGN: We performed a case-control study using enzyme-linked immunosorbent assays to detect matrix metalloproteinase-8 in 77 amniotic fluid specimens that were obtained by amniocentesis from women with preterm contractions or preterm labor and intact fetal membranes (n = 66) and from women with preterm premature rupture of membranes (n = 11). RESULTS: Thirty women had culture-proven intra-amniotic infection (cases), 21 of whom had intact membranes. After constructing receiver operating characteristic curves to establish the optimal threshold concentration of matrix metalloproteinase-8 for a positive test result, we detected matrix metalloproteinase-8 in 27 of 30 women with intra-amniotic infection; only 10 of 47 control specimens contained matrix metalloproteinase-8 (P <.001; odds ratio, 33.3; 95% CI, 8.4, 132.7). Matrix metalloproteinase-8 was present in 20 of 21 women with intact membranes and intra-amniotic infection and in only 10 of 45 control subjects (P <.001; odds ratio, 70.0; 95% CI, 8.3, 587.6). Among women with intact membranes, the sensitivity of the assay was 0.95 and the specificity was 0.78. CONCLUSION: Our results indicate that matrix metalloproteinase-8 is highly correlated with intra-amniotic infection and that enzyme-linked immunosorbent assay for matrix metalloproteinase-8 may be a clinically useful test for the diagnosis of intra-amniotic infection in women with preterm contractions and preterm labor.

Amnion↗
PubMed1983

The effect of amniotic fluid aspiration on pulmonary function in the adult and newborn rabbit.

Aspiration of uncontaminated human amniotic fluid was investigated in adult and newborn rabbits and compared with three other experimental groups: 10% meconium solution, saline, and sham-injected controls. Fluids were injected into the trachea of adult animals (4 or 6 ml/kg body weight), newborn vaginally-delivered animals (a mean volume of 8 ml/kg), and cesarean-delivered animals before their first breath (a mean volume of 11 ml/kg). In adult animals aspirating amniotic fluid or saline, arterial PO2 measured over a 24-h period showed a mean difference between groups of less than 5% for both 4 and 6 ml/kg. Meconium aspiration produced a greater depression in PO2 than amniotic fluid aspiration (a mean difference of 16 and 31% for 4 and 6 ml/kg, respectively) and animals aspirating meconium showed a deteriorating trend over 24 h, whereas animals aspirating amniotic fluid improved. One of eight adult animals aspirating amniotic fluid died versus four of five aspirating meconium. All five animals aspirating saline 6 ml/kg survived. Lung weight and resting volume of adult animals aspirating amniotic fluid were not significantly different from animals aspirating saline or nothing. Lung pressure volume curves from adult animals aspirating amniotic fluid were nearly identical to controls. Histology showed significantly greater atelectasis in adult animals that received 6 ml/kg amniotic fluid than controls, but this was not different from saline. There was no association between the number of cells in amniotic fluid and arterial PO2 after aspiration or any other aspect of pulmonary function measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniotic Fluid↗
PubMed2005

Effect of amniotic fluid on coagulation and platelet function in pregnancy: an evaluation using thromboelastography.

Amniotic fluid embolism is a rare obstetric complication. The exact pathogenesis of this syndrome remains unknown and significant controversy exists whether coagulopathy should always be present. We used thromboelastography to assess the effect of amniotic fluid on coagulation and platelet function in pregnant women. Different volumes of amniotic fluid (10-60 microl) were added to blood (330 microl) from pregnant women and thromboelastography variables determined. There were three important findings. R time, reflecting time to first clot formation, was significantly decreased with the addition of 10 microl amniotic fluid; platelet function, as determined by Reopro-TEG technique, was increased with the addition of 30 microl of amniotic fluid; and there was no evidence of fibrinolysis in any samples studied. In conclusion, our study substantiates the hypothesis that coagulation profile changes are invariable accompaniments of amniotic fluid embolism.

Adult↗
PubMed1977

Mammotrophic activity in rat amniotic fluid.

Mammotrophic activity was present in rat amniotic fluid collected on days 13, 15 and 19 of pregnancy. The mammotrophic activity in the fluid was equivalent to that in the maternal serum on day 15, but is was lower on day 19. The effect of tha amniotic fluid was similar to that of human placental lactogen on the rat mammary gland in vitro. The prolactin concentration in the amniotic fluid was low (approximately 1 ng/ml).

Amniotic Fluid↗
PubMed1987

Effects of alterations of zinc-to-phosphorus ratios and meconium content on group B Streptococcus growth in human amniotic fluid in vitro.

Several authors have described the bacterial growth-altering properties of amniotic fluid. We examined Group B Streptococcus growth in aseptically obtained amniotic fluid in vitro after altering its zinc, phosphorus, and meconium contents. Zinc and phosphorus levels were calculated in amniotic fluid and in meconium. Separate solutions of zinc and phosphorus were added to yield concentrations of 0.7, 7.0, 70, and 700 mumol. The solutions were incubated with Group B Streptococcus III 893 and Escherichia coli C5 strains, and 24-hour growth curves were plotted. Meconium, 0.5 mg/ml, was added to each amniotic fluid + zinc and amniotic fluid + phosphorus solution, and growth curves were plotted. The rate of proliferation of Group B Streptococcus varied directly with the zinc concentration (700 = 70 greater than 7 greater than 0.7 mumol) and inversely with the phosphorus content (700 less than 70 less than 7 = 0.7 mumol). Meconium enhanced the proliferative effect of zinc and hindered the inhibitory effect of phosphorus. Thus one possible mechanism whereby meconium enhances bacterial growth in amniotic fluid may be by alteration of zinc-to-phosphorus ratios.

Amniotic Fluid↗
PubMed1976

Transference of para-amino-hippurate from the mother to the amniotic fluid.

There are few studies in which substances mainly cleared by the kidney are injected to the mother and the time course of their concentrations in amniotic fluid is analyzed. This type of studies may contribute to the knowledge of the transference of substances through the mother-fetus-amniotic fluid complex. Thirteen pregnant women were studied. Eleven with normal term pregnancies, and the remaining two mothers were at the 36th week of gestation and their fetuses were dead. A saturation dose of para-amino-hippurate (PAH) (8 mg/kg) was administered intravenously to all subjects. This dose was followed by a continuous infusion at a rate of 380 mcg/min/kg during 30 minutes in 11 mothers. In one of the remaining subjects, the infusion rate was 240 mcg/min/kg during 160 minutes and in the other, it was 50 mcg/min/kg for 450 minutes. Samples of maternal blood and amniotic fluid were simultaneously obtained, before PAH administration and at variable intervals thereafter. In mothers with live fetuses, PAH concentration in amniotic fluid increased not only during the infusion but also for at least two hours after its interruption (Fig. 2, Tab. I). When the infusion lasted enough and with stabilized PAH concentration in maternal plasma, amniotic fluid concentration of PAH attained higher values than in the mother (Fig. 1). Disappearance of PAH from amniotic fluid was very slow (45% in 5 hours) (Fig. 2). In cases with dead fetuses, the pattern of PAH concentration in amniotic fluid was completely different. The highest concentration was observed already in the first sample at the end of the infusion. From there on, no increment was recorded, and as soon as maternal blood concentration fell below the values of amniotic fluid, PAH began to disappear from this compartment at a much faster rate (45% in 1 hour) (Fig 3). The progressive rise of PAH in amniotic fluid may be explained as follows: (Fig. 5). PAH diffuses from maternal blood to fetal blood through the placenta. The fetal kidney removes PAH from fetal blood and concentrates it in urine. Periodic fetal micturition causes the rise of PAH in amniotic fluid. PAH may return from amniotic fluid to fetal blood mainly because of fetal swallowing; and the larger part of this PAH will be again excreted by the kidney into the amniotic compartment. This mechanism would explain the slow disappearance of the substance from amniotic fluid after the end of the infusion, and also the lack of correlation between concentrations in maternal plasma and amniotic fluid. Diffusion of PAH between blood and amniotic fluid may also exist through the walls of the vessels of the ovular membranes and the vessels of the umbilical cord; this mechanism would play a minor role in the concentration of PAH in amniotic fluid in subjects with live fetuses. Our results also show that mean PAH concentration in amniotic fluid increases as a linear function of time until 150 minutes after the onset of PAH administration to the mother (Fig. 4).

Aminohippuric Acids↗
PubMed2005

[Activity of nuclear factor kappa B in rat pulmonary tissue after entrance of amniotic fluid into blood and inhibition with dexamethasone].

OBJECTIVE: To investigate the relationship between nuclear factor kappa B (NF-kappaB) and pulmonary injury in amniotic fluid embolism model of rat. METHODS: Seventy female Wistar rats were divided into five groups randomly: control group (6), amniotic fluid group (16), amniotic fluid + dexamethasone group (14), meconium group (20) and meconium + dexamethasone group (14). Different amniotic fluid was injected into jugular vein (dexamethasone was injected at 0.1 mg/100 g after entrance of amniotic fluid into blood) and blood pressure was examined. Pulmonary tissue was taken at 60 minutes. NF-kappaB activity was measured by Western-blot and percentage of NF-kappaB p65 positive cells in pulmonary tissue was determined by immunohistochemistry (HE). RESULTS: Dropsy, bleeding and neutrophil (PMN), macrophage, leukomonocyte infiltration were seen in four experimental groups. But none was found in control group. NF-kappaB activity in meconium group was 438,698 +/- 13,092, higher than those in amniotic fluid group, 377,982+/- 7,445, and in control group, 267,691 +/- 12 382 (F = 11.3, P < 0.01). With dexamethasone treatment, NF-kappaB activity was decreased, which was 308,826 +/- 13,771 in amniotic group and 339,516 +/- 17,358 in meconium group, respectively (t = 20.4 and t = 13.84, P < 0.01). Percentage of NF-kappaB p65 positive cells was higher in meconium group, 49.1 +/- 7.0, than in amniotic fluid group, 33.3 +/- 2.7, and control group, 13.3 +/- 2.1 (F = 1.17, P < 0.01). With dexamethasone treatment, the percentage decreased significantly to 22.9 +/- 3.0 and 21.4 +/- 3.6, respectively (t = 6.75 and t = 10.1, P < 0.05). CONCLUSIONS: NF-kappaB activity and percentage of NF-kappaB p65 positive cells are increased significantly, which is associated with pulmonary injury after entrance of amniotic fluid into blood and dexamethasone could inhibit NF-kappaB translocation to the nucleus to degrade NF-kappaB activity and alleviate pulmonary injury. NF-kappaB may be relevant to the occurrence and development of multiple organ dysfunction syndrome.

Amniotic Fluid↗
PubMed1985

Altered prolactin bioactivity in amniotic fluid of hypertensive pregnancy.

The high concentrations of prolactin (hPRL) in human amniotic fluid appear to be derived principally from maternal decidua. The present study evaluated both the biologic and immunologic activity of amniotic fluid hPRL obtained from normal and selected complicated pregnancies. Biologic and immunologic activities of amniotic fluid hPRL were also compared with lecithin:sphingomyelin ratios and phosphatidylglycerol content. No significant correlation existed between amniotic fluid hPRL activities and fetal lung maturation. However, a significant increase in amniotic fluid hPRL concentration as well as specific biologic activity of the hormone was found in pregnancies complicated by hypertension. These findings suggest alterations in the synthesis of decidual hPRL and/or its transport to the amniotic fluid that may influence pregnancy-induced hypertension.

Amniotic Fluid↗
PubMedDate not supplied

Enzymes in amniotic fluid.

The determination of enzyme levels in cell-free amniotic fluid has proven useful in assessing fetal maturity and fetal well being, and is being utilized for the prenatal diagnosis of genetic disorders. The activities of amylase, alpha-galactosidase, phosphatidic acid phosphohydrolase, lysozyme and heat-stable alkaline phosphatase in amniotic fluid increase with gestational age and have an established relationship to fetal maturity. The ratio of amniotic fluid diamine oxidase activity to maternal serum activity (amniotic DAO/serum DAO) may be used as an indicator of the degree of rhesus isoimmunization after 28 weeks gestation. Creatine phosphokinase in amniotic fluid is elevated in cases of in utero fetal death and is of diagnostic significance. The prenatal diagnosis of Tay-Sachs disease, Sandhoff's disease, fucosidosis, GM1-gangliosidosis and I-cell disease have been made from the analysis of appropriate enzymes in cell-free amniotic fluid.

Alkaline Phosphatase↗
PubMed1985

Amniotic fluid embolism. Three case reports with a review of the literature.

Amniotic fluid embolism is a catastrophic event of the intra- and early postpartum period which may also be seen with cesarean delivery and during abortions. Presenting symptomatology includes respiratory distress with cyanosis, shock, and possibly tonic-clonic seizures. DIC frequently occurs. The pathogenesis may include entry of amniotic fluid through lacerations or ruptures of the uterus or cervix, through endocervical veins and through abnormal uteroplacental sites, such as with placental abruption, placenta previa, or placenta accreta. Amniotic fluid probably causes cardiovascular-respiratory symptoms by pulmonary vascular obstruction and through a vasoactive substance causing pulmonary vascular constriction. The lethality of amniotic fluid may be enhanced by a high particulate content or meconium staining. The diagnosis of amniotic fluid embolism may be made ante mortem by demonstrating amniotic fluid debris in central blood samples or expectorated sputum. Postmortem diagnosis often requires meticulous examination of the pulmonary microvasculature with the utilization of special stains. Treatment is directed towards symptoms of shock, arterial hypoxemia, and DIC. Acute renal failure may complicate the picture after shock. If the patient survives the embolic and coagulative problems, recovery is usually complete without long-term sequelae.

Abortion, Missed↗
PubMed1978

Total and free cortisol in amniotic fluid during late pregnancy.

Total cortisol levels were measured in 81 samples of amniotic fluid obtained from 72 patients in the third trimester of pregnancy; 19 of them had pre-eclampsia and the remainder had no pre-eclampsia, hypertension or renal disease. In accordance with previous studies, there was a rise in the concentration of amniotic fluid cortisol with advancing gestation; the rise was steepest after 40 weeks, the amniotic fluid cortisol levels invariably being above 700 nmol/l between 41 and 43 weeks of pregnancy. Amniotic fluid cortisol may thus be of value in diagnosing postmaturity. A relatively low correlation was found between total cortisol levels and lecithin/sphingomyelin ratios in amniotic fluid unless results were ranked for gestational age. Total cortisol concentrations in amniotic fluid obtained from patients with pre-eclampsia were significantly higher than in controls. The concentration of free cortisol in amniotic fluid changed much less than total cortisol. Thus total cortisol should be measured in studies of the fetal capacity to synthesize corticosteroids.

Amniotic Fluid↗
PubMed1989

Serum and amniotic fluid melatonin during human labor.

The serum and amniotic fluid concentrations of melatonin (MT) were measured by RIA during human labor in different conditions related to the type of delivery and the time of the day of delivery. Serum MT concentrations displayed a normal diurnal rhythm, resembling that of nongravid women; the mean concentration [163.8 +/- 149.6 (+/- SD) pmol/L] at night was significantly (P less than 0.001) higher than that during the day (31.4 +/- 16.3 pmol/L). The amniotic fluid MT concentration, which showed a significant positive correlation to the serum MT concentration (r = 0.625; P less than 0.01), also showed an obvious diurnal rhythm; the mean MT concentration was significantly (P less than 0.01) higher during the night [99.3 +/- 59.3 (+/- SD) pmol/L] than during the day (58.9 +/- 33.5 pmol/L). Reverse phase high pressure liquid chromatography confirmed that the amniotic fluid MT immunoreactivity eluated as synthetic MT. During the night the mean amniotic fluid MT concentration [99.3 +/- 59.3 (+/- SD) pmol/L] was significantly (P less than 0.01) lower than that in serum (178.9 +/- 189.6 pmol/L). The progress of delivery, estimated by cervical dilatation, did not affect serum MT concentrations. Induction of delivery by amniotomy and/or oxytocin, and operative delivery by cesarean section had no effect on serum MT concentrations. Human MT secretion does not seem to be influenced by the physical stress of labor or endocrine changes associated with parturition. The single factor regulating MT secretion during human delivery appears to be the time of day.

Adult↗
PubMed1995

Accuracy of ultrasonography in evaluating amniotic fluid volume at less than 24 weeks' gestation.

The purpose of this investigation was to evaluate the accuracy of common sonographic techniques in assessing the amniotic fluid volume in pregnancies of less than 24 weeks' gestation. Patients at less than 24 weeks' gestation undergoing an amniocentesis for the placement of prostaglandin F2 alpha for termination (because of genetic or fetal anomalies, or both) were assessed for amniotic fluid volume. All fetuses were alive at the time of prostaglandin instillation. The amniotic fluid index and two-diameter pocket were used to determine the amniotic fluid volume. Prior to the prostaglandin instillation, the amniotic fluid volume was determined with para-aminohippurate using a diazo dye reaction with spectrophotometric analysis. The amniotic fluid volume was determined in 21 pregnancies between 15 and 24 weeks' gestation, yielding volumes ranging from 189 to 1840 ml. Using published standards for amniotic fluid volume in singleton pregnancies, oligohydramnios was present in three gestations, the volume was found to be normal in 15, and hydramnios complicated three pregnancies. The two-diameter pocket identified the amniotic fluid volumes correctly more often (18 of 21 [85.7%]) than the amniotic fluid index (10 of 21 [47.6%]) (P = 0.02). Normal amniotic fluid volume was identified in nine of 15 (60%) pregnancies by the amniotic fluid index and in 14 of 15 (93.3%) by the two-diameter pocket (P = not significant). Abnormal amniotic fluid volumes, oligohydramnios, and hydramnios were recognized more often by the two-diameter pocket (66.7%) than by the amniotic fluid index (1 of 6 [16.7%], P = not significant).

Abortion, Induced↗
PubMed1990

The neuropeptide histidyl proline diketopiperazine throughout human pregnancy: an inverse correlation with amniotic fluid prolactin.

Histidyl proline diketopiperazine values have been established in human amniotic fluid (n = 81) and maternal serum (n = 36) throughout gestation (10 to 42 weeks). Newborn cord serum (n = 10) and first-voided fetal urine (n = 10) levels were also documented. These measurements reveal increasing amniotic fluid levels with term gestation values (15,551 pg/ml) nearly thirteen-fold higher than maternal serum concentrations (1150 pg/ml). Corresponding fetal urine and cord serum concentrations were 16,781 and 2160 pg/ml, respectively. The amniotic fluid values are not influenced by fetal sex or maternal labor, nor do they correlate with amniotic fluid alpha-fetoprotein levels. However, there is a significant inverse correlation (r = -0.628; p less than 0.0001) between amniotic fluid prolactin and histidyl proline diketopiperazine after midgestation. The hypothesis that histidyl proline diketopiperazine may be a regulatory peptide for decidual prolactin production was tested by culturing term decidua in the presence of varying concentrations of histidyl proline diketopiperazine, but no inhibitory effect was observed. Decidual cultures did not produce measurable amounts of histidyl proline diketopiperazine. It is suggested that amniotic fluid histidyl proline diketopiperazine is derived from fetal urine.

Adolescent↗
PubMed1984

Angiotensin I-converting enzyme in amniotic fluid.

Angiotensin I-converting enzyme (ACE) is present in human amniotic fluid. We characterized the enzyme by both its antigenic and enzymatic properties. Using a specific direct radioimmunoassay, ACE was quantified and characterized in each of the 19 samples tested. Mean level was 136 +/- 83 ng/ml. Amniotic ACE completely crossreacted, like that in plasma and kidney, with antibodies raised against the lung enzyme. ACE activity in amniotic fluid averaged 8.7 +/- 5.6 microU/ml using Hip-His-Leu as substrate and was significantly correlated with ACE antigen levels. ACE was not associated with the cells or the free intracellular organelles in amniotic fluid, and the enzyme was present in soluble form. Angiotensinase activity and high levels of kininase activity were found in amniotic fluid. Inhibition studies with captopril and anti-human ACE antibodies suggest that angiotensinases and kininases other than ACE were also present. Because renin, mostly in inactive form, and angiotensinogen were also found in these amniotic fluids, it appears that a complete, although not fully activated, renin angiotensin system is present in amniotic fluid and fetal membranes during pregnancy.

Adult↗