Amniotic Fluid Erythropoietin Levels Research Articles

Amniotic fluid and umbilical cord serum erythropoietin in term and prolonged pregnancies

ObjectiveErythropoietin - a hormone regulating erythropoiesis - is a biomarker of chronic fetal hypoxia. High erythropoietin levels in fetal plasma and amniotic fluid are associated with increased risk of adverse neonatal outcome. Since the risk of perinatal morbidity and mortality is increased in pregnancies beyond 41 gestational weeks, we evaluated erythropoietin levels in amniotic fluid and umbilical cord serum in apparently low-risk term (≥ 37 gestational weeks) and prolonged pregnancies (≥ 41 gestational weeks) with labor induction. Study designThis prospective cohort study comprised 93 singleton pregnancies at 37+0-42+1 gestational weeks, of which prolonged pregnancies numbered 63 (67.7%). Amniotic fluid samples were collected at time of labor induction by amniotomy. Umbilical cord blood samples for evaluation of pH, base excess, and umbilical cord serum erythropoietin were collected at birth. Erythropoietin levels were measured by immunochemiluminometric assay. Normal value of amniotic fluid erythropoietin level was defined as ≤ 3 IU/L, and abnormal value as ≥ 27 IU/L. Normal umbilical cord serum erythropoietin was defined as < 40 IU/L. Data on maternal pregnancy and delivery characteristics and short-term neonatal outcomes such as Apgar score were obtained from the hospital charts. Associations were calculated using Spearman’s rank correlation coefficient. The Chi-square test, Fisher’s exact test and the Mann-Whitney U test were utilized to determine differences in the study groups. ResultsAmniotic fluid erythropoietin levels correlated with gestational age (r = 0.261, p = 0.012) and were higher among prolonged pregnancies as compared to term pregnancies (p = 0.005). There were 78 (83.9%) vaginal deliveries, and among these erythropoietin levels in amniotic fluid correlated with the levels in umbilical cord serum (r = 0.513, p < 0.000). Umbilical cord serum erythropoietin levels correlated with gestational age among vaginal deliveries (r = 0.250, p = 0.027). Erythropoietin levels in amniotic fluid and umbilical cord serum did not correlate with umbilical artery pH or base excess, or other adverse pregnancy outcome. ConclusionsIn vaginal deliveries erythropoietin levels in amniotic fluid correlated with the levels in umbilical cord serum. Erythropoietin levels correlated with gestational age, probably due to weakening placental function and relative hypoxemia occurring in advanced gestation. However, in this relatively low-risk study population erythropoietin was not related to adverse delivery outcome.

Late pregnancy amniotic fluid erythropoietin (EPO) levels in women with and without type 1 diabetes

Tripterygium preparations (TPs), a traditional Chinese Medicines extracted from Tripterygium wilfordii Hook f., are widely used for treatment of rheumatoid arthritis (RA). However, TPs from different Pharmaceutical factory have different efficacy and side effects for RA treatment.The purpose of the current study is to evaluate the efficacy and safety of four TPs from different Pharmaceutical factory in china on the treatment of collagen-induced arthritis (CIA) rats and provide a theoretical and experimental basis for the individualized use of TPs.The model of wistar rats of CIA was made, and the rats were perfused a stomach with four TPs for 3 weeks continuously. Then arthritis severity was determined by visual examination of the paws and histopathologic changes of joint, liver, kidney and testis were determined by hematoxylin–eosin (H&E) staining. The expression of inflammatory cytokines (IL-1β, TNF-α, IL-17 and IL-6) in the joint was analyzed by real-time PCR, and the count and motion parameters (sperm motility and progressive sperm) of sperm in cauda epididymis were assessed with computer-assisted sperm analysis (CASA) system. Routine blood tests were conducted using automated hematology analyzer, and the aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, creatinine (Cr), and blood urea nitrogen (BUN) in serum of CIA rats were measured using a UniCel DxC 880i autoanalyzer.All of tested TPs could reduce inflammatory score, histopathological arthritis severity and joint׳s inflammatory cytokines (IL-1β, TNF-α, IL-17 and IL-6) expression in CIA rats, however, TP-D showed stronger inhibitory effect for inflammatory score compared with other three TPs in vivo. All of tested TPs did not show hepatotoxicity and nephrotoxicity and also had little effect for the concentration of hemoglobin (Hb) and the count of white blood cell (WBC). Analysis of red blood cell (RBC) number showed that TP-C and TP-D could reverse lower RBC number in untreated CIA rats to normal level. Interestingly, the results showed TPs named TP-C and TP-D could decrease platelet (PLT) number which significantly increases in untreated CIA rats. Reproductive toxicity, the main side effect of TPs, assay showed that the sperm quality (density, viability, and motility) in four of TPs-treated CIA rats were decreased significantly, consistently with spermatogenic cell density reduced. However parallel analysis showed that in four TPs-treated rats, the number of sperm, motile sperm and progressive sperm were highest in TP-D group, in contrast, were lowest in TP-C group.These findings suggested that four TPs showed significantly therapeutic effect on ameliorating inflammation of CIA rats, with no obvious hepatotoxicity and nephrotoxicity in vivo. TP-D showed advantages with its higher efficacy and less reproductive toxicity as well as increasing RBC number, decreasing PLT number in CIA treatment. Thus, in the development of individualized treatment plan for RA patients, TP-D might be considered preferentially.

Amniotic Fluid Oxidative and Nitrosative Stress Biomarkers Correlate with Fetal Chronic Hypoxia in Diabetic Pregnancies

Background: In spite of improvement in obstetrical care, pregnancy in women with type 1 diabetes mellitus is associated with increased perinatal morbidity and mortality. Hyperglycemia during pregnancy causes excessive fetal growth and chronic fetal hypoxia as reflected in increased erythropoietin (EPO) levels in amniotic fluid (AF). Objectives: We hypothesized that the degree of fetal hypoxia would correlate with fetal oxidative and nitrosative stress as evidenced by the concentration of specific biomarkers in AF. Material and Methods: 19 pregnant women with type 1 or insulin-treated gestational diabetes mellitus were studied. AF samples were collected and processed for EPO, meta-tyrosine, nitro-tyrosine and 8-hydroxy-2-deoxiguanosine by chemiluminescent immunoassay and high-performance liquid chromatography coupled to tandem mass spectrometry methods, respectively. Results: The mean (SD) of the last HbA_1c concentration before delivery was 7.7% (1.1). Median gestational age was 258 days (range 231–268). Birth weight was 3,868 ± 695 g with a z-score >2 SD in 47% of the cases. A significant correlation was found between the concentrations of AF EPO and meta-tyrosine/phenylalanine ratio (p < 0.001), nitro-tyrosine (p < 0.01) and 8-oxo-dG/2dG ratio (p < 0.001). Conclusions: We confirmed that fetuses of type 1 diabetes or insulin-treated gestational diabetes pregnancies experience chronic hypoxia as reflected by increased EPO concentrations in AF near term. Moreover, EPO levels significantly correlated with the concentration of oxidative and nitrosative stress biomarkers in AF. This pro-oxidant status may predispose newborn infants to poor postnatal adaptation and early neonatal complications.

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, pO₂ 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.

High amniotic fluid erythropoietin levels are associated with an increased frequency of fetal and neonatal morbidity in Type 1 diabetic pregnancies

In this study we investigated whether chronic fetal hypoxia, as indicated by amniotic fluid erythropoietin levels, is associated with perinatal morbidity in type 1 diabetic pregnancies. A total of 331 women with type 1 diabetes had at least one childbirth between 1995 and 2000. The amniotic fluid erythropoietin concentration was measured in 156 diabetic singleton pregnancies at a median time of 1 day before Caesarean section without labour contractions and in 19 healthy control subjects at Caesarean section. The median amniotic fluid erythropoietin level was 14.0 mU/ml (range 2.0-1975.0) in diabetic pregnancies and 6.3 mU/ml (range 1.7-13.7) in controls (p<0.0001). Of the 156 diabetic patients, 21 (13.5%) had amniotic fluid erythropoietin levels higher than 63.0 mU/ml. Amniotic fluid erythropoietin levels correlated negatively with umbilical artery pH (r=-0.49, p<0.0001) and pO2 (r=-0.62, p<0.0001) at birth and neonatal lowest blood glucose level (r=-0.47, p<0.0001). Positive correlations were found between amniotic fluid erythropoietin levels and umbilical artery pCO2 (r=0.49, p<0.0001) and last maternal HbA1c (r=0.43, p<0.0001). Furthermore, a U-shaped correlation was demonstrated between amniotic fluid erythropoietin levels and birthweight z score (z score below -0.6 SD units: r=-0.63, p=0.0007; z score above +1.0 SD units: r=0.32, p=0.0014). Neonatal hypoglycaemia, hypertrophic cardiomyopathy and admission to the neonatal intensive care unit occurred significantly more often in cases with high amniotic fluid erythropoietin levels (>63.0 mU/ml) than in those with normal levels. Multivariate logistic regression analysis revealed that amniotic fluid erythropoietin was the only variable independently related to low umbilical artery pH (<7.21; p<0.0001) and neonatal hypoglycaemia (p=0.002). Low umbilical artery pO2 (<15.0 mm Hg) was explained by amniotic fluid erythropoietin (p<0.0001) and birthweight z score (p=0.004). Antenatal high amniotic fluid erythropoietin levels can identify type 1 diabetic pregnancies at increased risk of severe perinatal complications.

Relationship between erythropoietin levels both in cord serum and amniotic fluid at birth and abnormal fetal heart rate records.

Our data in rats suggest that an elevated amniotic fluid erythropoietin (EPO) level at birth indicates antepartum fetal hypoxia. However, the short gestation period in rats does not permit a direct comparison of our data with humans. We conducted a retrospective study of the relationship between EPO levels at birth and abnormal fetal heart rate (FHR) records in 113 infants. Among the cesarean section group, the cord serum and amniotic fluid EPO levels in the infants with antepartum abnormal FHR records were significantly higher than those in the control infants. Among the vaginal delivery group, the cord serum EPO levels in the infants with intrapartum abnormal FHR records was significantly higher than that in the control infants. The EPO levels in either cord serum and amniotic fluid discriminated between infants with antepartum abnormal FHR records. The control infants had a sensitivity of 83% and a specificity of 96%. Six of the seven infants with abnormal EPO levels in both cord serum and amniotic fluid had symptoms of prolonged fetal hypoxia. Five infants with abnormal EPO levels in only cord serum had symptoms of acute fetal hypoxia before birth. Four of the 14 infants with abnormal EPO levels at birth had poor outcomes in the neonatal period. We concluded that EPO levels in both cord serum and amniotic fluid at birth are valuable for determining the timing of fetal hypoxia and may predict the outcome in the neonatal period.

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

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. 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. 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. 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.

P101Doppler flow velocimetry in fetal and maternal circulation in relation to blood serum and amniotic fluid erythropoietin levels

ObjectiveTo correlate arterial Doppler flow velocimetry with amniotic fluid and umbilical cord erythropoietin levels and umbilical cord gasometry.Material and methodsThe study compromised 80 pregnant woman who delivered in cesarean section without prior uterine contractions. The AB, PI and RI indexes of fetal umbilical, cerebral arteries as well as uterine arcuate arteries was assessed max. 24 h before delivery. Amniotic fluid was collected during the cesarean section before the uterine incision and umbilical cord blood was retrieved after the delivery, 1 min after the cord was clamped.ResultsThe correlation was found between umbilical arteries AB ratio and amniotic erythropoietin levels, fetal serum erythropoietin levels as well as umbilical artery pO2 and apgar score 5 min after delivery. The correlation was also found between fetal blood and amniotic fluid erythropoietin levels.ConclusionsDoppler flow velocimetry of umbilical artery reflects the fetal and newborn well being. Umbilical cord and amniotic fluid erythropoietin levels reflect fetal oxygenation. Erthropoietin levels may be checked in amniotic fluid beceause amniocentesis is related to lower incidence of complications in comparisone with cordocentesis.

Fetal erythropoietin and endothelin-1: relation to hypoxia and intrauterine growth retardation

We have examined whether endothelin-1 (ET-1) and erythropoietin (EPO) in amniotic fluid, and EPO in fetal serum obtained by cordocentesis from fetuses with signs of intrauterine growth retardation (IUGR), were correlated to fetal growth and/or chronic fetal hypoxia. Amniotic fluid and fetal serum were obtained by cordocentesis from 28 fetuses suspected to have IUGR and subsequently analyzed for EPO and ET-1 by ELISA. These data were correlated to blood gas results and fetal/maternal parameters at delivery. A novel finding was that ET-1 correlated to PO2 in amniotic fluid. The average level of ET-1 in amniotic fluid was 48.3+/-4.7 pmol/L. The results also showed a correlation between EPO levels in amniotic fluid and EPO in fetal serum. Furthermore, EPO correlated weakly to birth weight at delivery. Children with the lowest birth weights had the highest EPO levels. High EPO values, similarly to ET-1, correlated to low pO2 values. The level of EPO in amniotic fluid was 8.0+/-1.6 mIU/ml and in cord blood 29.5+/-9.6 mIU/ml. The results indicate that ET-1 levels may be a marker for short-term hypoxia, but not for fetal growth, since ET-1 in amniotic fluid was correlated to PO2 at the time of cordocentesis, but not to birth weight. The results also indicate that EPO levels in amniotic fluid and in fetal cord serum are highly correlated, and thus both can be used as markers for fetal growth and chronic hypoxia before the onset of labor.

Erythropoietin in amniotic fluid as a marker of chronic fetal hypoxia

Objective: To determinate the erythropoietin concentration in amniotic fluid in normal pregnancies and pregnancies with suspected hypoxia. Method: The erythropoietin concentration of 164 samples of amniotic fluid was determined by ELISA. The samples were taken by amniotomy during birth, as well as amniocentesis conducted during prenatal care. Results: A distribution of 1.07–7.29 U/l (10th–90th percentile) within the normal group (n=106) was determined. Significantly elevated erythropoietin levels in amniotic fluid were determined in maternal hypertension (P=0.039) and low birth-weight children (P=0.0032). A correlation with the child's sex could be excluded. Conclusion: Elevated erythropoietin levels in amniotic fluid indicated chronic fetal hypoxia.

Can amniotic fluid erythropoietin levels differentiate between acute or chronic causes of fetal death?

Can amniotic fluid erythropoietin levels differentiate between acute or chronic causes of fetal death?

Effect of hypoxia on amniotic fluid erythropoietin levels in fetal rats.

Erythropoietin (EPO) levels in amniotic fluid and serum were measured in hypoxic (fraction of inspired oxygen, FiO2, 0.09) and posthypoxic (following a 24-hour period of hypoxia, FiO2 0.09) fetal rats on day 21 of gestation. Each of the study groups comprised 12-20 fetuses. Each of the control groups consisted of 21 or 22 fetuses. Fetal serum EPO levels at 3, 6, 9, 12, and 24 h of hypoxia were significantly higher than the control level. Amniotic fluid EPO levels at 9, 12, and 24 h of hypoxia were also significantly increased compared to the control level. Fetal serum EPO levels returned to baseline during the 12- to 48-hour period after hypoxia. During the 0- to 48-hour posthypoxic period, amniotic fluid EPO levels were significantly higher than the control level. These data demonstrate that rates of appearance and turnover of amniotic fluid EPO are different from those of fetal serum EPO.

Detection of erythropoietin in amniotic fluid

To investigate the concentrations of amniotic fluid erythropoietin in normal and risk pregnancies. The concentrations of erythropoietin were measured in 150 samples of amniotic fluid. The samples were obtained by amniocentesis and amniotomia and were analysed using an enzyme-linked immunosorbent assay (ELISA). Results were available within 6 hours. The intra-assay variation was 6.4%, the inter-assay variation 7.2%. The range of erythropoietin concentration in all samples was between 0.23 and 80 U/L and in a defined group of normal pregnancies between 1.20 and 6.53 U/L (10%-90% percentile). Correlation was found between the concentration of erythropoietin and maternal hypertension (p = 0.0159), amnion infection syndrome in combination with premature birth (p = 0.0593), fetal growth retardation (p = 0.784), and base-excess (p = 0.0487). Elevated erythropoietin concentrations were found in a defined risk group with Apgar scores below 7 after 1 minute (p = 0.072) and after 5 minutes (p = 0.0037). There is a connection between postpartal transfer to the intensive-care unit and elevated erythropoietin concentrations (p = 0.073). No influence is exercised by the child's sex on the concentration of erythropoietin. No significant connection was found between the level of erythropoietin and smoking during pregnancy, volume of amniotic fluid and maturity at birth. A critical erythropoietin concentration could be postulated at 12 U/L. Children with higher levels showed heavy and severe disorders. Elevated erythropoietin levels in amniotic fluid indicate prolonged fetal hypoxaemia. Using the ELISA-technique a rapid prepartal determination of such situations is possible and might be helpful in the clinical procedure.

The effect of regular maternal exercise on erythropoietin in cord blood and amniotic fluid

OBJECTIVE: Our purpose was to test the hypothesis that continuing regular, high-intensity exercise until the onset of labor produces significant fetal hypoxemia, as evidenced by elevated erythropoietin levels in the fetal compartment. STUDY DESIGN: Erythropoietin levels were measured in samples of amniotic fluid and cord blood obtained from fetuses born to 31 exercising women and 29 matched controls. RESULTS: Erythropoietin levels (mean ± SEM) in amniotic fluid obtained at the time of membrane rupture (9 ± 2 vs 11 ± 2 mU/ml) and in cord blood (38 ± 6 vs 53 ± 16 mU/ml) and amniotic fluid at delivery (9 ± 1 vs 24 ± 12 mU/ml) were no different in women who exercised regularly until the onset of labor. In both groups the majority of elevated cord blood levels (>50 mU/ml) could be explained by labor events. Amniotic fluid erythropoietin levels correlated directly ( r = 0.52) with cord blood hematocrit and increased slowly during labor. CONCLUSION: We conclude that the initial hypothesis is incorrect and speculate that cord blood erythropoietin reflects fetal oxygenation during labor, whereas amniotic fluid erythropoietin primarily reflects the adequacy of oxygenation before the onset of labor.

Erythropoietin levels in umbilical cord plasma and amniotic fluid as a measure of chronic fetal hypoxia

Erythropoietin levels in umbilical cord plasma and amniotic fluid as a measure of chronic fetal hypoxia

Amniotic fluid erythropoietin levels in normal and Down's syndrome pregnancies

The aim of this study was to measure the levels of erythropoietin in amniotic fluid from normal and trisomy 21 pregnancies at 10 to 20 weeks gestation. Samples of amniotic fluid were collected from 142 women with singleton pregnancies after genetic amniocentesis; 110 had a normal fetal karyotype and 32 had trisomy 21. Erythropoietin was measured using a double antibody radioimmunoassay. Amniotic fluid erythropoietin levels in normal pregnancies increased from 10 weeks (mean 3.2 mU/ml; range < 2.0–6.3 mU/ml) to 20 weeks gestation (mean 7.9 mU/ml; range 2.0–11.5 mU/ml). There was a significant linear correlation between gestational age and erythropoietin levels ( r = 0.543; P < 0.0001). For the 32 patients with trisomy 21 pregnancies the median multiple of the median (MoM) was 1.11 (range 0.42–2.1). There was no difference between erythropoietin levels in amniotic fluid from normal and Down's syndrome pregnancies ( U = 2352, P = 0.75, 95% CI = −0.11, 0.18); (Mann-Whitney U-test).

Maternal and Fetal Erythropoietin: Physiological Aspects and Clinical Significance

Erythropoietin (EPO) is of special interest in the perinatal period in the mother and fetus. On the one hand, thanks to the recent development of highly sensitive radio-immunoassays and the ability to monitor endogenous EPO production, we can now study the physiological aspects of maternal and fetal erythropoiesis and materno-fetal interrelations, and diagnose raised EPO levels as markers of oxygen deficiency. On the other hand, the availability of recombinant human EPO (rHuEPO) permits therapeutic intervention against anaemia during and after pregnancy. This paper reviews available studies showing a rise in maternal and fetal EPO levels in parallel with gestational age and, in certain pathological states of pregnancy, grossly raised EPO levels in amniotic fluid and fetal blood entirely unrelated to maternal values. The theoretical and experimental arguments against transplacental passage of EPO in the human are discussed. Initial results with rHuEPO have shown rapid correction of maternal post-partum anaemia. No studies on its use during pregnancy are available to date.

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

The aim was to measure erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid from 7-12 weeks' gestation. Twenty healthy women with ultrasonographically normal first trimester pregnancies prior to surgical termination. 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. 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. 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 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.