Amniotic fluid S100B protein and erythropoietin in pregnancies at risk for fetal hypoxia

Objective

S100B protein is a biochemical marker for brain injury, and high serum S100B levels have been observed in newborns with birth asphyxia. We hypothesized that the concentration of amniotic fluid erythropoietin, which increases in chronic fetal hypoxia, correlates with amniotic fluid S100B concentration.

Study design

Amniotic fluid samples in 35 pregnancies at high risk for chronic fetal hypoxia were obtained at cesarean section or by amniocentesis done within a median of 2 days before delivery. S100B and erythropoietin concentrations were measured by chemiluminescent immunoassays.

Results

A positive correlation existed between the concentrations of S100B and erythropoietin in the amniotic fluid (r = 0.57, p < 0.0001). Amniotic fluid S100B concentration was higher (70 ng/l; 33–469, n = 17) (median; range) in pregnancies with elevated amniotic fluid erythropoietin (≥50 IU/l) than in pregnancies with normal erythropoietin (34 ng/l; 20–340, n = 18) (p < 0.0001, Mann–Whitney U-test). S100B predicted an elevated amniotic fluid erythropoietin concentration in the study population with the sensitivity of 94% and specificity of 83%.

Conclusion

A strong positive correlation exists between amniotic fluid S100B and erythropoietin concentrations in pregnancies at high risk for chronic fetal hypoxia. This suggests that chronic fetal hypoxia increases the intrauterine release of S100B.     

Concentration of cord serum placenta growth factor in normal and diabetic pregnancies

OBJECTIVE: To investigate whether maternal diabetes or diabetes-related complications, such as macrosomia and chronic fetal hypoxia, are associated with altered placenta growth factor (PlGF) levels in cord serum. DESIGN: Case-control study. SETTING: Helsinki University Central Hospital, Helsinki, Finland. POPULATION: Sixty-two normal pregnancies, 67 pregnancies complicated by type 1 diabetes and 28 pregnancies complicated by insulin-treated gestational diabetes. METHODS: Cord serum PlGF concentration was measured by an enzyme-linked immunosorbent assay. Amniotic fluid erythropoietin concentration was measured by a chemiluminescent immunologic method. Umbilical artery gas variables were analysed with standard blood gas and pH electrodes. MAIN OUTCOME MEASURE: PlGF concentration in cord serum at birth. RESULTS: Cord serum PlGF concentration was similar in normal pregnancies [13.4 (1.0) ng/L], in pregnancies complicated by type 1 diabetes [15.1 (1.8) ng/L, P= 0.583 vs controls] and in pregnancies complicated by insulin-treated gestational diabetes [13.6 (0.9) ng/L, P= 0.991 vs controls]. Cord serum PlGF did not correlate with relative birthweight. In diabetic pregnancies, cord serum PlGF correlated negatively with amniotic fluid erythropoietin (r=-0.449, P < 0.0001) and positively with umbilical artery Po(2) (r= 0.333, P= 0.001). There was a trend toward lower cord serum PlGF levels in diabetic pregnancies with pre-eclampsia compared with those without any hypertensive disorders. CONCLUSIONS: Maternal diabetes per se is not associated with altered PlGF levels in cord serum. The correlation between PlGF and indices of fetal hypoxia in diabetic pregnancies may be related to the role of PlGF in potentiating the angiogenic response to vascular endothelial growth factor in ischaemia.     

Vascular endothelial growth factor, nitric oxide, and leptin follicular fluid levels correlate negatively with embryo quality in IVF patients

Objective(s): To measure vascular endothelial growth factor (VEGF), nitric oxide (NO) and leptin levels in individual ovarian follicles and to examine their relationships with perifollicular blood flow, follicular metabolic indices, and the developmental potential of the corresponding oocyte and embryo.

Design: Prospective study.

Setting: Academic, tertiary care institution.

Patient(s): Unselected IVF patients.

Intervention(s): Color-pulsed Doppler analysis of perifollicular blood flow; determination of partial pressure of oxygen (pO₂), partial pressure of carbon dioxide (pCO₂), and pH and VEGF, leptin and NO levels in follicular fluid.

Main Outcome Measure(s): Fertilization and day 3 embryo morphology and cleavage.

Result(s): Fifty-five follicular fluid samples from 16 patients were studied. Mean follicular fluid levels were as follows: VEGF, 1,046 ± 863.7 pg/mL (range, <63–3,332.7 pg/mL); NO₃/NO₂, 34.2 ± 12 μM (range, 16.4–76.1 μM); and leptin, 20.1 ± 12.1 ng/mL (range, 3.3–52.2 ng/mL). Vascular endothelial growth factor had a negative correlation with embryo morphology (r = −0.28, P=.01). Leptin demonstrated a negative correlation with follicular pO₂ (r = −0.42, P=.005) and a positive correlation with follicular pCO₂ (r = 0.36, P=.02). Follicular leptin levels correlated positively with VEGF levels (r = 0.46, P=.008) and with NO₃/NO₂ levels (r = 0.39, P=.006).

Conclusion(s): Vascular endothelial growth factor, NO and leptin appear to be markers of follicular hypoxia and suboptimal embryo development. Whether fluctuations of these regulatory factors determine or reflect changes in the follicular microenvironment affecting oocyte developmental potential remains to be elucidated.     

Fetal lung surfactant and development alterations in intrahepatic cholestasis of pregnancy

AIM: To investigate the association between total bile acid (TBA) level during intrahepatic cholestasis of pregnancy (ICP) and fetal lung surfactant alteration. METHODS: We recruited 42 ICP and 32 normal pregnancy women in this study. The maternal blood, fetal blood and amniotic fluid TBA level were detected using a circulating enzymatic method. Umbilical blood pulmonary surfactant protein A (SP-A) was evaluated with enzyme-linked immunosorbent assay. High performance liquid chromatography was used for the determination of phosphatidyl choline (PC), phosphatidyl inositol (PI), lysolecithin (LPC) and sphingomyelin (SM). Amniotic fluid lamellar body was counted with a fully automatic blood cell counter. Fetal lung area and fetal body weight were calculated from data obtained with an iu22 color supersonic diagnostic set. Clinical information of a nonstress test, amniotic fluid properties and neonatal Apgar score, and birth weight were recorded for review. RESULTS: The TBA level in maternal blood, fetal blood and amniotic fluid in the ICP group were significantly higher than that in the control group (maternal blood: 34.11 ± 6.75 mmol/L vs 4.55 ± 1.72 mmol/L, P < 0.05; fetal blood: 11.9 ± 2.23 mmol/L vs 3.52 ± 1.56 mmol/L, P < 0.05; amniotic fluid: 3.89 ± 1.99 mmol/L vs 1.43 ± 1.14 mmol/L, P < 0.05). Amniotic fluid PC and PI in the ICP group were significantly lower than that in the control group (PC: 65.71 ± 7.23 μg/mL vs 69.70 ± 6.68 μg/mL, P < 0.05; PI: 3.87 ± 0.65 μg/mL vs 4.28 ± 0.74 μg/mL, P < 0.05). PC/LPC ratio of the ICP group was lower than that of the control group (14.40 ± 3.14 vs 16.90 ± 2.52, P < 0.05). Amniotic LB in the ICP group was significantly lower than that of the control group ((74.13 ± 4.37) × 10⁹/L vs (103.0 ± 26.82) × 10⁹/L, P < 0.05). Fetal umbilical blood SP-A level in the ICP group was significantly higher than that of the control group (30.26 ± 7.01 ng/mL vs 22.63 ± 7.42 ng/mL, P < 0.05). Fetal lung area/body weight ratio of the ICP group was significantly lower than that of the control group (5.76 ± 0.63 cm²/kg vs 6.89 ± 0.48 cm²/kg, P < 0.05). In the ICP group, umbilical cord blood TBA concentration was positively correlated to the maternal blood TBA concentration (r = 0.746, P < 0.05) and umbilical blood SP-A (r = 0.422, P < 0.05), but it was negatively correlated to the amniotic fluid lamellar corpuscle (r = 0.810, P < 0.05) and fetal lung area/body weight ratio (r = 0.769, P < 0.05). Furthermore, umbilical blood TBA showed a negative correlation to PC, SM and PI (r_pc = 0.536, r_sm = 0.438, r_pi = 0.387 respectively, P < 0.05). The neonatal asphyxia, neonatal respiratory distress syndrome, fetal distress and perinatal death rates in the ICP group are higher than that of the control group. CONCLUSION: ICP has higher TBA in maternal and fetal blood and amniotic fluid. The high concentration of TBA may affect fetal pulmonary surfactant production and fetal lung maturation.     

Amniotic fluid and cord plasma erythropoietin levels in pregnancies complicated by preeclampsia, pregnancy-induced hypertension and chronic hypertension

AIMS: The purpose of the present study was to compare fetal and neonatal outcomes with amniotic fluid erythropoietin (EPO) levels obtained in the antepartum period in pregnancies complicated by preeclampsia, pregnancy-induced hypertension or chronic hypertension. METHODS: Erythropoietin concentrations were measured in amniotic fluid within 2 days before delivery and in cord blood at birth in 75 hypertensive women and in 23 healthy controls delivered by cesarean section before labor contractions. Erythropoietin levels did not influence clinical decisions. RESULTS: Amniotic fluid erythropoietin levels correlated highly significantly with cord plasma EPO levels and were significantly higher in pregnancies complicated by hypertension than in control pregnancies. Umbilical arterial pH, acid-base and blood gas values at birth were not different from controls. Both cord plasma and amniotic fluid erythropoietin levels correlated with cord blood pH, acid-base and blood gas values at birth in the study group. Newborn infants admitted to the newborn intensive care unit had significantly higher fetal erythropoietin levels and were more acidotic, hypoxemic and hypoglycemic than infants admitted to the normal care nursery. CONCLUSIONS: Our findings suggest that elevated amniotic fluid erythropoietin levels are markers of chronic or subchronic fetal hypoxia and are associated with neonatal morbidity in pregnancies complicated by hypertension.     

The effect of nuchal cord on amniotic fluid and cord blood erythropoietin at delivery

OBJECTIVE: We investigated the effect of a nuchal cord on fetal hypoxia by using amniotic fluid and cord blood erythropoietin as markers of chronic and acute hypoxia, respectively. METHODS: A total of 167 full-term pregnancies without maternal complications or fetal prelabor complications except fetal growth restriction of unknown cause were studied prospectively. Of these, 47 had a nuchal cord at delivery, and 62 had one or more complications during labor and delivery (nonreassuring fetal heart rate pattern, birth weight less than 2500 g, Apgar score at 1 minute less than 7, presence of meconium-stained amniotic fluid, oligohydramnios), and 26 had both nuchal cord and at least one of the intrapartum complications. RESULTS: Erythropoietin levels (mean +/- standard error of the mean) were not significantly different between the nuchal cord group (n = 47) and the no nuchal cord group (n = 120) in either amniotic fluid (19.3 +/- 4.1 mU/mL versus 13.7 +/- 1.1 mU/mL) or cord blood (57.9 +/- 10.3 mU/mL versus 52.1 +/- 4.9 mU/mL). Similarly, in the 62 fetuses with intrapartum complications, there were no significant differences in amniotic fluid (14.3 +/- 2.0 mU/mL versus 18.8 +/- 2.9 mU/mL) or cord blood erythropoietin (66.9 +/- 16.8 mU/mL versus 72.6 +/- 12.6 mU/mL) levels between those with (n = 26) or without a nuchal cord (n = 36). Among the 107 uncomplicated cases, however, amniotic fluid erythropoietin was significantly elevated in the nuchal cord group (25.5 +/- 8.7 mU/mL, n = 21) compared with that in the no nuchal cord group (11.5 +/- 0.9 mU/mL, n = 84) (P <.05), whereas there was no significant between-group difference in cord blood erythropoietin levels between nuchal cord and no nuchal cord groups (46.8 +/- 10.0 mU/mL versus 43.3 +/- 4.1 mU/mL). Tightness of the nuchal cord did not affect amniotic fluid or cord blood erythropoietin concentrations. CONCLUSION: Although nuchal cord may not significantly increase the risk of acute or labor-associated fetal hypoxia, it appears to be an independent risk factor of mild, chronic, prelabor fetal hypoxia.     

Erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid in the first trimester of pregnancy.

OBJECTIVE: The aim was to measure erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid from 7-12 weeks' gestation. SUBJECTS: Twenty healthy women with ultrasonographically normal first trimester pregnancies prior to surgical termination. METHODS: Paired samples of amniotic fluid and extraembryonic coelomic fluid were collected by transvaginal ultrasound guided needling. Erythropoietin was measured in both pregnancy fluids using a radioimmunoassay. RESULTS: There was a highly significant difference between erythropoietin levels in extraembryonic coelomic fluid (median level 15.45 mU/ml; range 6.8-32.1 mU/ml) and those in amniotic fluid (median 5.0 mU/ml; range < 5.0-5.8 mU/ml) (P < 0.0001; Mann-Whitney U-test). The levels of erythropoietin in maternal serum (median 15.4 mU/ml; range 5.6-29.4 mU/ml) were similar to those in the extra-embryonic coelom (P = 0.81; Mann-Whitney U-test). No relation was demonstrated between erythropoietin levels in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSION: High levels of erythropoietin in coelomic fluid suggests that the hormone is involved in the process of human extraembryonic erythropoiesis. The exact regulatory role remains unknown.     

Amniotic fluid erythropoietin concentrations differentiate between acute and chronic causes of fetal death

BACKGROUND: Increased fetal plasma erythropoietin concentration is an indicator of chronic fetal hypoxia. Amniotic fluid erythropoietin levels correlate highly significantly with fetal erythropoietin levels before labor. We studied AF erythropoietin levels after fetal death in order to determine whether this could differentiate between stillbirths from acute or chronic causes. METHODS: Amniotic fluid was obtained after fetal death for erythropoietin measurement following fetal death in 21 pregnancies. Two of the pregnancies had twins, of which one infant was born alive. All 22 stillborn fetuses had an autopsy. None had malformations. Without prior knowledge of the results of the erythropoietin analyzes, the causes of fetal death were divided into acute, chronic or unknown groups. RESULTS: Eight pregnancies had an acute cause of fetal death (e.g. cord complication or placental abruption), eight pregnancies had a chronic cause (intrauterine growth restriction or erythroblastosis) and in five pregnancies the cause of fetal death could not be determined. In all eight pregnancies with an acute cause of fetal death, AF erythropoietin levels were normal (< 20 mU/mL). In contrast, six of the eight pregnancies with a chronic cause had AF erythropoietin levels above normal (range from 49.9 mU/mL to 391 mU/mL). In the five pregnancies with an unknown cause of fetal death, AF erythropoietin levels were normal in three and elevated in two. CONCLUSIONS: Elevated AF erythropoietin levels, identified after fetal death, suggest that the fetus died from a chronic hypoxic event, whereas normal AF erythropoietin levels suggest that the fetus died from an acute event.     

Influence of postdatism and meconium on fetal erythropoietin.

OBJECTIVE: To determine whether fetal erythropoietin (Epo) concentrations are increased in pregnancies extending beyond 41 weeks' gestation and whether this is influenced by the presence of meconium-stained amniotic fluid. METHODS: Epo concentrations were measured in 116 fetal umbilical cord blood samples from otherwise uncomplicated pregnancies between 37 to 43 weeks' gestation during the period of October 1996 to October 1997. An enzyme-linked immunosorbent assay kit was used to measure Epo. Maternal demographics and birth outcomes including Apgar score, cord blood pH, and base deficit were obtained. Fetuses born between 41 and 43 weeks' gestation (post-term) were compared with matched controls born between 37 and 40 weeks' gestation (term). In addition, both post-term and term fetuses with meconium-stained amniotic fluid were compared with matched controls without meconium. RESULTS: Post-term fetuses without meconium had significantly higher Epo levels compared with term fetuses (mean +/- SEM: 50.6 +/- 6.5 versus 29.5 +/- 3.3 mIU/ml, p = 0.002). When matched for gestational age, fetuses with meconium-stained amniotic fluid had significantly greater Epo concentrations compared with controls without meconium (post-term, 80.7 versus 50.6 mIU/ml; term, 61.4 versus 29.5 mIU/ml; p < 0.05). However, no significant difference in Epo levels was found between post-term fetuses with meconium and term fetuses with meconium (80.7 +/- 15.7 mIU/ml versus 61.4 +/- 12.8 mIU/ml, respectively). Mean cord blood pH and base deficit values for all groups were within normal clinical range. CONCLUSION: Cord blood Epo concentrations were significantly increased in pregnancies extending beyond 41 weeks. Irrespective of gestational age, meconium-stained amniotic fluid was associated with a significant rise in Epo. High Epo levels in these pregnancies imply subacute or chronic fetal hypoxia. Close clinical monitoring of post-term fetuses and those with meconium-stained amniotic fluid is warranted.     

Unexplained elevated serum hCG is associated with raised amniotic fluid erythropoietin levels in second-trimester pregnancies.

OBJECTIVE: This study was designed to investigate the association between the concentrations of maternal serum hCG and amniotic fluid erythropoietin during the second trimester of pregnancy. METHODS: In a prospective case-control study, 42 consecutive singleton pregnancies showing unexplained elevated serum hCG concentrations (>2.0 multiples of the median, MoM) in Down's syndrome screening and 27 control pregnant women undergoing midtrimester amniocentesis because of a previous cytogenetic abnormality were studied. RESULTS: The mean amniotic fluid erythropoietin concentration in the study group was 1.8 (range 0.61-8.7) MoM, whereas it was 1.1 (range 0.71-3. 96) MoM in the controls (p = 0.035). A significantly increasing relationship (p < 0.05) was found between the concentrations of maternal serum hCG and amniotic fluid erythropoietin. CONCLUSIONS: The results of the current study revealed in vivo the association between elevated hCG and amniotic fluid erythropoietin levels which, in turn, supports the concept of early placental damage. The underlying pathology seems to be sufficient to cause an erythroblastic response.     

Meconium stained amniotic fluid in very low risk pregnancies at term gestation

Objective: To determine the prevalence and clinical significance of meconium stained amniotic fluid (MSAF) in a low risk population at term gestation and to investigate whether MSAF is a predictor for intrapartum and neonatal morbidity. Methods: A very low risk population including 37 085 consecutive deliveries at term composed the study population. A cross-sectional study was conducted and two groups of patients were identified according to the presence (n=6164) or absence (n=30 921) of meconium in the amniotic fluid at delivery and the outcomes of the two groups compared. Results: The prevalence of MSAF was 16.6%. The incidence of cesarean section (5.6% vs 2.3% P<0.01), instrumental deliveries (3.2% vs 1.8% P<0.01), fetal distress (6.5% vs. 2.1% P<0.01), clinical chorioamnionitis (0.2% vs. 0.1% P<0.01), post-partum infection (0.5% vs. 0.2% P<0.01), 1-minute Apgar score <3 (1.9% vs. 1.1% P<0.01), small for gestational age (7.4% vs. 6.4% P<0.01). was significantly higher in the MSAF compared with the clear amniotic fluid group. Intrapartum and neonatal mortality in this low risk population was significantly higher in the MSAF group ( ) compared with women with clear AF ( ). Conclusions: MSAF in a low risk population at term gestation is a predictor for adverse perinatal outcome and peripartum complications.     

Amniotic fluid beta-2-microglobulin in normal and complicated pregnancies. Correlation with gestational age, creatinine concentration and L/S ratio

The beta-2-microglobulin concentrations in 127 aminotic fluid samples, obtained during weeks 32-42 of normal pregnancies (n = 58) and complicated pregnancies (n = 69), were measured and correlated with gestational weeks, amniotic fluid creatinine concentrations and L/S ratios. A significant (p less than 0.001) decrease of beta-2-microglobulin concentration occurred from week 32 to 34 of normal pregnancies, after which the beta-2-microglobulin level was unchanged. There were no significant correlations between beta-2-microglobulin concentrations and amniotic fluid creatinine concentrations of LK/S ratios. The beta-2-microglobulin content was elevated in samples obtained from diabetic and toxemic pregnancies. Measurement of beta-2-microglobulin in amniotic fluid seems to be of limited value for determining fetal age, but it may be useful in estimating fetal renal maturity.     

Amniotic fluid erythropoietin correlates with umbilical plasma erythropoietin in normal and abnormal pregnancy

In the human fetus, elevated plasma erythropoietin levels have been found in high-risk pregnancies at delivery. We examined the relationship of amniotic fluid erythropoietin and umbilical plasma erythropoietin at delivery in 17 normal pregnancies, 41 hypertensive pregnancies, and 37 insulin-treated diabetic pregnancies terminated by elective cesarean section without labor. An additional 27 insulin-treated diabetic patients were studied after undergoing variable durations (86-1184 minutes) of labor. Erythropoietin was analyzed using a highly sensitive and specific radioimmunoassay technique. Fetal plasma erythropoietin concentrations were elevated above the control upper range (50.3 mU/mL) in 59% of the hypertensives and in 38% of the diabetics. The amniotic fluid erythropoietin values were significantly lower than the umbilical plasma erythropoietin values in each study group. Although the umbilical plasma erythropoietin values in the abnormal pregnancy groups differed considerably from the corresponding levels in the controls, the ratio of amniotic fluid erythropoietin to umbilical plasma erythropoietin was approximately the same in controls, hypertensives, and diabetics. Furthermore, the plasma and amniotic fluid levels (In transformed) correlated highly significantly in all three individual groups in absence of labor. In the diabetic labor group, this relationship was nonsignificant. We conclude that in the absence of labor, amniotic fluid erythropoietin reflects fetal plasma erythropoietin. We speculate that amniotic fluid erythropoietin may be an antepartum indicator of fetal hypoxemia.     

Increased fetal plasma and amniotic fluid erythropoietin concentrations: markers of intrauterine hypoxia

Tissue hypoxia is the major stimulus of erythropoietin (EPO) synthesis in fetuses and adults. Since EPO does not cross the placenta and is not stored, fetal plasma and amniotic fluid levels indicate EPO synthesis and elimination. Acutely, the rate and magnitude of the increase in plasma EPO levels correlate with the intensity of hypoxia. Amniotic fluid EPO levels correlate with cord plasma levels in normal and abnormal pregnancies, with fetal plasma EPO levels in humans averaging 2.6 times higher than the corresponding amniotic fluid EPO levels. Recent experimental and clinical studies demonstrate that EPO has neuroprotective effects related to its anti-apoptotic and vascular growth-promoting properties. Although under basal conditions the fetal kidneys are the main site of EPO production, during hypoxia recent experimental data indicate an important role of the placenta. Amniotic fluid EPO levels have been shown to increase exponentially during fetal hypoxia in preeclamptic, diabetic and Rh-immunized pregnancies, to correlate inversely with cord blood pH, pO(2) and base excess and to predict neonatal morbidities and NICU admission. As an indicator of chronic intrauterine hypoxia, fetal EPO measurements have increased our knowledge about the pathogenesis and importance of intrauterine growth restriction, macrosomia, diabetic pregnancy, prolonged pregnancy, meconium staining, fetal hemorrhage, fetal anemia, maternal smoking and alcohol consumption, abnormal fetal heart rate and abnormal Doppler flow patterns. While the clinical utility of fetal amniotic fluid and plasma EPO measurements in the management of high-risk pregnancies and their offspring is promising, adequately powered clinical trials are urgently needed.     

Neuron specific enolase in amniotic fluid--a possible indicator for fetal distress and brain implication

It can be suggested that a NSE concentration in body fluids above the normal range may indicate brain damage, because NSE is found in neurons and neuroendocrine cells only. In this paper the concentration of the neuron specific enolase (NSE) in the amniotic fluid of normal and high risk pregnancies was investigated. Sixty-three samples of amniotic fluid were collected from 55 pregnant women and women in labor between the 19th and the 42nd gestational week. In 24 normal pregnancies 1.02 +/- 0.31 microgram NSE/L (mean +/- SD) were found. A relationship of NSE concentration was not found for gestational age, uterine contractions, age and parity of the mother, infant's birth weight or 1 min Apgar score. Maternal diseases such as diabetes mellitus, hypertension and others do not result in any increase of NSE concentration in the amniotic fluid (N = 20; 1.06 +/- 0.24 microgram NSE/L). Fetal and birth related high risk factors such as meconium stained amniotic fluid, cord around the neck, severe decelerations of the fetal heart rate or combinations of these factors caused the NSE concentration to exceed significantly normal values (N = 17; 2.22 +/- 0.87 microgram NSE/L). Due to its high organ and cell specificity, NSE may be a possible parameter for brain damage due to hypoxia in the fetus and newborn; however, only subsequent neurological and psychological examinations of these children can indicate the prognostic value of an elevation of NSE concentration in amniotic fluid.     

Intra-amniotic pressure is not affected by amniocentesis between 13 and 18 weeks of gestation

Changes in amniotic fluid pressure before and after amniocentesis fell within the range of ± 5 mmHg, except when uterine contractions were present. Intra-amniotic pressure is not affected by amniocentesis between 13 and 18 weeks of gestation. Amniotic fluid pressure was recorded in 82 pregnancies of patients undergoing genetic amniocentesis to determine whether sampling of amniotic fluid between 13 and 18 weeks changed intra-amniotic pressure. Pressures were recorded through a needle and saline filled catheter with a zero-level at the needle tip. Amniotic fluid pressure was unrelated to gestational age (P = 0.962) during the weeks we performed our measurements. Fluid samples of 12.6% of the total volume in a group of early genetic amniocentesis (n = 65) and of 7.5% of the total volume in a group of late genetic amniocentesis (n = 17) did not change significantly amniotic fluid pressure values. An increase in pressure of more than 5 mmHg only occurred in cases where uterine contractions were present. Other than these cases, all pressure change values fell within the range of ± 5 mmHg. No difference in pregnancy outcome were present within the two groups. An argument for a standard method for stationing pressure is presented.     

Amniotic fluid erythropoietin predicts fetal distress in Rh-immunized pregnancies

Repeated amniotic fluid erythropoietin measurements in 23 Rh-immunized pregnancies were done to evaluate erythropoietin levels of amniotic fluid as an indicator of fetal distress (umbilical artery, pH 7.14 or less, or 1-minute Apgar score of 4 or less). Amniotic fluid erythropoietin levels did not vary significantly between 168 and 273 gestational days in the pregnancies without fetal distress. Increasing levels of amniotic fluid erythropoietin predicted highly reliably severe fetal distress at birth. Whether erythropoietin levels of amniotic fluid can also predict fetal distress in other pathologic pregnancies needs further study.     

Biochemical composition of amniotic fluid in pregnancies complicated with twin-twin transfusion syndrome

OBJECTIVE: To compare the electrolyte composition of pregnancies complicated with twin-twin transfusion syndrome (TTTS) with that of physiologic pregnancies. MATERIALS AND METHODS: Amniotic fluid samples from 16 pregnancies were studied. Specimens were obtained from recipient sacs in 10 pregnancies undergoing fetoscopy for severe midtrimester TTTS. Additionally, 6 amniotic fluid samples were obtained transcervically from legal second-trimester pregnancy terminations. The concentrations of sodium, potassium, chloride, bicarbonate, calcium, glucose, osmolality, pH, total protein content and albumin were determined in each sample. RESULTS: The mean gestational age at sampling was 20.2 weeks (range 17.2-27.1) in the TTTS group and 18.4 (range 16.0-22.0) in the control group (p = NS). We found significant lower levels of albumin (0.22 +/- 0.04 vs. 0.39 +/- 0.11, p = 0.01) and total protein (0.19 +/- 0.08 vs. 0.51 +/- 0.17, p < 0.001) and higher levels of bicarbonate (16.90 +/- 1.45 vs. 14.50 +/- 2.17, p = 0.02) in amniotic fluid samples taken from recipient sacs of TTTS pregnancies. CONCLUSION: Amniotic fluid from the receptor in severe midtrimester TTTS differs significantly from control amniotic fluid samples in bicarbonate concentration, total protein content and albumin concentration. These findings may help to understand the pathophysiology of TTTS and to optimise therapeutic modalities.     

Vitamin A concentration in amniotic fluid and maternal serum related to neural-tube defects

The vitamin A concentration of amniotic fluid and maternal serum was measured during the second trimester of pregnancy in 106 women, 12 of whom had a baby with a neural-tube defect. In these 12 pregnancies the amniotic fluid vitamin A concentration was significantly higher than in 94 normal pregnancies. There was a highly significant correlation between amniotic fluid vitamin A and both zinc and alpha-fetoprotein (AFP) levels. The maternal serum vitamin A levels were also significantly related to serum zinc levels. Women with a raised serum AFP level, but a normal baby, had significantly higher amniotic fluid vitamin A levels and significantly lower serum vitamin A levels compared with those in women with normal serum AFP levels.     

Amniotic fluid beta-endorphin and alpha-melanocyte--stimulating hormone immunoreactivity in normal and complicated pregnancies

beta-Endorphin (beta-EP) and alpha-melanocyte--stimulating hormone (alpha-MSH) are members of a family of peptides which are found in the intermediate lobe of the fetal pituitary gland and placenta. In the present study, concentrations of immunoreactive beta-EP (i beta-EP) and alpha-MSH were determined by radioimmunoassay in the amniotic fluid compartment of both normal (n = 72) and complicated (n = 44) pregnancies. In normal pregnancies, there was a significant (p less than 0.05) fall in the mean amniotic fluid i beta-EP from the second to third trimester (from 175 to 132 pg/ml). A similar, but not statistically significant, decline in the mean amniotic fluid concentrations of alpha-MSH (from 46 to 34 pg/ml) was also noted. Concentrations of amniotic fluid i beta-EP showed a significant correlation with alpha-MSH (r = 0.61, p less than 0.001). Significant elevations of mean amniotic fluid i beta-EP but not alpha-MSH were found in pregnancies complicated by intrauterine growth retardation (215 pg/ml, p less than 0.001) and premature labor (225 pg/ml, p less than 0.001). Our findings suggest that levels of i beta-EP and alpha-MSH in amniotic fluid decrease from the second to the third trimester of pregnancy, and that elevation in i beta-EP concentration in amniotic fluid, in all probability, reflects the secretion of beta-EP by the fetus in response to fetal distress.