Erythropoietin and cord blood haemoglobin in the regulation of human fetal erythropoiesis

Umbilical Cord Erythroferrone Is Inversely Associated with Hepcidin, but Does Not Capture the Most Variability in Iron Status of Neonates Born to Teens Carrying Singletons and Women Carrying Multiples

BACKGROUND

The developing fetus requires adequate iron and produces its own hormones to regulate this process. Erythroferrone (ERFE) is a recently identified iron regulatory hormone, and normative data on ERFE concentrations and relations between iron status and other iron regulatory hormones at birth are needed.

OBJECTIVES

The objective of this study was to characterize cord ERFE concentrations at birth and assess interrelations between ERFE, iron regulatory hormones, and iron status biomarkers in 2 cohorts of newborns at higher risk of neonatal anemia.

METHODS

Umbilical cord ERFE concentrations were measured in extant serum samples collected from neonates born to women carrying multiples (age: 21-43 y; n = 127) or teens (age: 14-19 y; n = 164). Relations between cord blood ERFE and other markers of iron status or erythropoiesis in cord blood were assessed by linear regression and mediation analysis.

RESULTS

Cord ERFE was detectable in all newborns delivered between 30 and 42 weeks of gestation, and mean concentration at birth was 0.73 ng/mL (95% CI: 0.63, 0.85 ng/mL). Cord ERFE was on average 0.25 ng/mL lower in newborns of black as opposed to white ancestry (P = 0.04). Cord ERFE was significantly associated with transferrin receptor (β: 1.17, P < 0.001), ferritin (β: -0.27, P < 0.01), and hemoglobin (Hb) (β: 0.04, P < 0.05). However, cord hepcidin and the hepcidin:erythropoietin (EPO) ratio captured the most variance in newborn iron and hematologic status (>25% of variance explained).

CONCLUSIONS

Neonates born to teens and women carrying multiples were able to produce ERFE in response to neonatal cord iron status and erythropoietic demand. ERFE, however, did not capture significant variance in newborn iron or Hb concentrations. In these newborns, cord hepcidin and the hepcidin:EPO ratio explained the most variance in iron status indicators at birth.

Hematological changes in severe early onset growth-restricted fetuses with absent and reversed end-diastolic flow in the umbilical artery

BACKGROUND

Erythropoietin seems to play an important role in the regulation of fetal hypoxemia. The present prospective study was designed to determine if changes in erythropoietin levels can be found in fetuses with severe early-onset growth restriction and hemodynamic compromise.

METHODS AND RESULTS

Erythropoietin, hemoglobin, hematocrit, platelet counts, normoblasts, lacate, arterial and venous blood gasses in the umbilical cord were determined in 42 fetuses with fetal growth restriction (IUGR) with absent (zero-flow) and 26 IUGR fetuses with retrograde end-diastolic flow (reverse-flow) in the umbilical artery. Color Doppler measurements were performed on the middle cerebral artery (PI) and ductus venosus [(S-a)/D and (S-a)/Vmean]. Erythropoietin concentrations were significantly lower in the zero-flow group (median: 128.0 mU/mL; range: 60.3-213 mU/mL) compared with the reverse-flow group (median: 202.5 mU/mL; range: 166-1182 mU/mL). Significant differences in median lactate concentrations were observed between the zero-flow group: 3.28 mmol/L (range; 2.3-4.7 mmol/L), and reverse-flow group: 5.6 mmol/L (range: 3.8-7.5 mmol/L). Fetuses with reverse-flow had significantly lower median platelet counts than fetuses with zero-flow (74 vs. 155/μL) and significantly lower normoblast counts (63 vs. 342/100 WBC).

CONCLUSIONS

Fetuses with severe IUGR due to chronic placental insufficiency and absent or reversed flow in the umbilical artery show increased erythropoietin levels.

Effect of maternal body mass index on cord blood erthropoietin concentrations

OBJECTIVE

To examine the hypothesis that maternal body mass index (BMI) (an index of maternal adiposity) correlates with cord blood concentrations of erythropoietin (EPO).

STUDY DESIGN

Cross-sectional cohort study of consecutively born singleton term healthy infants born to mothers with various BMIs. Excluded were infants with major factors known to be associated with a potential increase in fetal erythropoiesis. Prepregnancy maternal BMI was calculated from maternal recollection.

RESULT

There was a significant correlation between EPO concentrations and maternal BMI (R = 0.427, P = 0.007). This correlation remained significant in multiple stepwise regression analysis using the EPO concentration as the dependent variable, and maternal age, parity, gestational age and Apgar scores (1 or 5 min) as potential confounders.

CONCLUSION

Cord blood concentrations of EPO correlate with maternal BMI. We speculate that increasing maternal BMI may represent a relative hypoxic burden on the fetus.

Erythropoietin in amniotic fluid as a potential marker in distinction between growth restricted and constitutionally small fetuses

OBJECTIVE

To determine if there is any difference in amniotic fluid erythropoietin (EPO) concentration between fetuses small for gestational age (SGA) and appropriate for gestational age (AGA), and between the constitutionally small (CSF) and growth-restricted (GRF) fetuses.

METHODS

EPO concentrations in the amniotic fluid samples were determined by EpoELISA test in 38 pregnancies with SGA and 15 pregnancies with AGA fetuses. In the SGA group we measured Ponderal index (PI) and skin-fold thickness (SFT). If PI and/or SFT were below 10th percentile the neonate was GRF. If both PI and SFT were above 10th percentile the neonate was CSF.

RESULTS

Higher levels of EPO were detected in the SGA in comparison to the AGA fetuses (p < 0.01). EPO concentration was higher in GRF compared to CSF (p < 0.05). The EPO cut-off level between SGA and AGA was 6.81 IU/L (sensitivity 92.3%; specificity 73.3%), and between GRF and CSF was 9.8 IU/L (sensitivity 81%; specificity 80%).

CONCLUSION

The preliminary results of this study suggest that amniotic fluid erythropoietin concentration is elevated in growth-restricted fetuses and could potentially be used for distinction between growth restricted and constitutionally small fetuses. Confirmation of these results on a larger group of pregnant women is needed.

Hematologic profile of the fetus with systemic inflammatory response syndrome

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is associated with impending onset of preterm labor/delivery, microbial invasion of the amniotic cavity and increased perinatal morbidity. FIRS has been defined by an elevated fetal plasma interleukin (IL)-6, a cytokine with potent effects on the differentiation and proliferation of hematopoietic precursors. The objective of this study was to characterize the hematologic profile of fetuses with FIRS.

STUDY DESIGN

Fetal blood sampling was performed in patients with preterm prelabor rupture of membranes and preterm labor with intact membranes (n=152). A fetal plasma IL-6 concentration ≥ 11 pg/mL was used to define FIRS. Hemoglobin concentration, platelet count, total white blood cell (WBC) count, differential count, and nucleated red blood cell (NRBC) count were obtained. Since blood cell count varies with gestational age, the observed values were corrected for fetal age by calculating a ratio between the observed and expected mean value for gestational age.

RESULTS

1) The prevalence of FIRS was 28.9% (44/152); 2) fetuses with FIRS had a higher median corrected WBC and corrected neutrophil count than those without FIRS (WBC: median 1.4, range 0.3-5.6, vs. median 1.1, range 0.4-2.9, P=0.001; neutrophils: median 3.6, range 0.1-57.5, vs. median 1.8, range 0.2-13.9, P<0.001); 3) neutrophilia (defined as a neutrophil count >95th centile of gestational age) was significantly more common in fetuses with FIRS than in those without FIRS (71%, 30/42, vs. 35%, 37/105; P<0.001); 4) more than two-thirds of fetuses with FIRS had neutrophilia, whereas neutropenia was present in only 4.8% (2/42); 5) FIRS was not associated with detectable changes in hemoglobin concentration, platelet, lymphocyte, monocyte, basophil or eosinophil counts; and 6) fetuses with FIRS had a median corrected NRBC count higher than those without FIRS. However, the difference did not reach statistical significance (NRBC median 0.07, range 0-1.3, vs. median 0.04, range 0-2.3, P=0.06).

CONCLUSION

The hematologic profile of the human fetus with FIRS is characterized by significant changes in the total WBC and neutrophil counts. The NRBC count in fetuses with FIRS tends to be higher than fetuses without FIRS.

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.

Neonatal nucleated red blood cells in infants of overweight and obese mothers

OBJECTIVE

The perinatal outcome of the infant of obese mother is adversely affected and in theory, may involve fetal hypoxia. We hypothesized that an index of fetal hypoxia, the neonatal nucleated red blood cell (NRBC) count, is elevated in infants of overweight and obese mothers.

STUDY DESIGN

Absolute NRBC counts taken during the first 12 hours of life in 41 infants of overweight and obese mothers were compared to 28 controls.

RESULTS

Maternal body mass index and infant birthweight were significantly higher in the overweight and obese group (P < 0.01). Hematocrit, corrected white blood cell and lymphocyte counts did not differ between groups. The absolute NRBC count was higher (P = 0.01), and the platelet count lower (P = 0.05) in infants of overweight and obese mothers than in controls. In stepwise regression analysis, the absolute NRBC count in infants of overweight and obese mothers remained significantly higher even after taking into account birthweight or gestational age and Apgar scores (P < 0.02).

CONCLUSION

Infants of overweight and obese mothers have increased nucleated red blood cells at birth compared with controls. We speculate that even apparently healthy fetuses of overweight and obese mothers are exposed to a subtle hypoxemic environment.

The effect of prolonged rupture of membranes on circulating neonatal nucleated red blood cells

OBJECTIVES

To test the hypothesis that absolute nucleated red blood cells (ANRBC) counts are higher at birth in infants who were born after prolonged rupture of membranes (PROM, >24 hours).

STUDY DESIGN

Retrospective study of 31 infants admitted to the neonatal intensive care unit who were born after PROM, and pair matched for gestational age and Apgar scores with 31 no PROM controls. Venous ANRBC counts were obtained within 1 hour of life.

RESULTS

Groups did not differ in birthweight, gestational age, Apgar scores, and platelets counts. The ANRBC counts and hematocrit were significantly higher in infants who were born after PROM than in controls.

CONCLUSIONS

Infants born after PROM have higher ANRBC counts at birth than control infants. We suggest that increased fetal erythropoiesis exists in infants who are delivered after PROM. If correct, our interpretation supports the theory that fetal hypoxia and/or ischemia may result from PROM.

Nucleated red blood cells in preterm infants with retinopathy of prematurity

OBJECTIVE

The aim of this retrospective study was to examine hematologic indices of potential intrauterine hypoxia, including circulating nucleated red blood cells, lymphocytes, and platelets in preterm infants who developed retinopathy of prematurity (ROP) compared with suitable controls. We hypothesized that higher neonatal absolute nucleated red blood cell (ANRBC) and lymphocyte counts and lower platelets would be found in infants who developed ROP, compared with control infants.

METHODS

Each of 23 infants with ROP was pair matched for gestational age and Apgar scores with a control without ROP. Criteria for exclusion in both groups included factors that may influence the ANRBCs at birth. Venous ANRBC counts were obtained within 1 hour of life. Statistical analyses used paired t tests, a paired Wilcoxon test, and backward stepwise-regression analysis.

RESULTS

Groups did not differ in birth weight, gestational age, Apgar scores, or hematocrit, white blood cell, or platelets counts. The ANRBC counts at birth were significantly higher in infants who developed ROP than in controls.

CONCLUSIONS

Infants who develop ROP have higher ANRBC counts at birth than matched controls. We suggest that increased fetal erythropoiesis exists in preterm infants who later on will develop ROP. If correct, our interpretation supports the theory that long-lasting fetal hypoxia and/or ischemia may play a role in the pathogenesis of ROP.

Nucleated red blood cells in concordant, appropriate-for-gestational age twins

OBJECTIVES

The purpose of this study was to test the hypothesis that neonatal nucleated red blood cell (RBC) counts are elevated in nondiscordant twins compared with singletons.

STUDY DESIGN

We compared absolute nucleated RBC counts taken after birth in 2 groups of term, appropriate-for-gestational age infants; 74 concordant twins, and 29 singleton control infants. We excluded infants with factors associated with a potential increase in absolute nucleated RBC counts.

RESULTS

Birth weight and gestational age were significantly lower in twins than in singletons (P < .01). Hematocrit, absolute nucleated RBC count, and corrected lymphocyte counts were significantly higher in twins (P < .01). In multiple regression, the significantly higher absolute nucleated RBC count in twins remained significantly higher even after taking into account gestational age and Apgar scores.

CONCLUSION

Concordant, appropriate-for-gestational age twins have increased nucleated RBCs at birth compared with singleton control infants.

Physiology of erythropoietin during mammalian development

Growth is a fundamental process of mammalian development. Several observations regarding regulation of erythropoiesis during growth are not easily explained by the hypoxia-erythropoietin (Epo) concept. This review focuses primarily on this aspect of the physiology of Epo. The question is raised of whether this regulation during growth is based on the hypoxia-Epo mechanism alone, or whether Epo acts in concert with general growth-promoting factors, particularly growth hormone (GH) and the insulin-like growth factors (IGF-I and -II). Supporting the latter hypothesis is the observation that the Epo and GH/IGF systems are activated by hypoxia and share similar receptors and pathways. Recent studies indicate that human fetal and infant growth is stimulated by GH, IGF-I and IGF-II. Epo, GH and IGFs are expressed early in fetal life. Although the rate of erythropoiesis in the fetus is high, serum Epo levels are low. The Epo response to hypoxia in the fetus and neonate is reduced compared with adults. Following delivery the Epo levels vary between species, probably related to the oxygen transport capacity of the hemoglobin (Hb) mass. IGF-I levels are low in the fetus and increase slowly following birth, except in preterm infants in whom the levels decline. In all mammals Hb declines following birth, giving rise to "early anemia". Except in the human, Epo levels increase proportionally with the fall in Hb, but there is a discrepancy between the curves for serum immunoreactive Epo (siEpo) and for erythropoiesis stimulating factors (ESF): the latter include other stimulatory factors in addition to Epo. Hypertransfusion of mice in the period of "early anemia" suppresses siEpo, but not ESF and erythropoiesis, as it does in adult mice. GH and IGF-I have direct effects on erythropoiesis in vitro and act particularly at the later stages of red cell differentiation. IGF-I acts synergistically with Epo, and its effects are most marked when Epo levels are low. Human recombinant (rhu) IGF-I stimulates erythropoiesis in neonatal rats, but not in newborn mice and lambs. In adult mice, in hypophysectomized rats and in mice with end-stage renal failure, however, a stimulatory effect of this growth factor was found on red cell production. RhuGH stimulates erythropoiesis in GH-deficient short children.

CONCLUSION

Fetal and early postnatal erythropoiesis are dependent on factors in addition to Epo. The likely candidates are GH and IGF-I. The in vitro stimulating effects of these factors on erythropoiesis are convincing, but more data are needed on the in vivo effects.

Nucleated red blood cells in infants of mothers with asthma

OBJECTIVE

The purpose of this study was to evaluate whether the absolute nucleated red blood cell and lymphocyte count is elevated in term, appropriate-for-gestational-age infants born to women with asthma.

STUDY DESIGN

We compared absolute nucleated red blood cell counts taken during the first 12 hours of life in two groups of term, vaginally delivered, appropriate-for-gestational-age infants; one group was born to mothers with active asthma during pregnancy (n = 28 infants), and the other group was born to control mothers (n = 29 infants). Asthma severity was classified according to the National Asthma Education and Prevention Program. We excluded infants of women with diabetes mellitus, hypertension, alcohol, and tobacco or drug abuse and infants with fetal heart rate abnormalities, hemolysis, blood loss, or chromosomal anomalies.

RESULTS

There were no differences between groups in birth weight, gestational age, maternal age, gravidity, parity, maternal analgesia during labor, 1- and 5-minute Apgar scores, and infant sex. The hematocrit level, red blood cell count, absolute nucleated red blood cell count, and corrected leukocyte and lymphocyte counts were significantly higher in the asthma group than in the control group. The platelet count was not significantly different between groups. The absolute nucleated red blood cell count correlated significantly with the asthma severity score (r (2) = 28%, P <.001). Backward stepwise multiple regression that included Apgar scores and gestational age showed a significant correlation of absolute nucleated red blood cell count with the presence of asthma and its severity (P <.001).

CONCLUSION

At birth, term appropriate-for-gestational-age infants born to mothers with asthma have increased circulating absolute nucleated red blood cell and lymphocyte counts compared with control infants.

Nucleated red blood cells in polycythemic infants

OBJECTIVE

This study was undertaken to evaluate whether the absolute nucleated red blood cell (RBC) count is elevated in term, appropriate-for-gestational-age (AGA) polycythemic infants.

STUDY DESIGN

We compared absolute nucleated RBC counts taken during the first 12 hours of life in term, AGA infants with neonatal polycythemia (n = 29), and in control, nonpolycythemic infants (n = 37). We excluded infants of women with diabetes, hypertension, and alcohol, tobacco, or drug abuse, and those with fetal heart rate abnormalities or low Apgar scores, hemolysis, blood loss, or chromosomal anomalies.

RESULTS

There were no differences between groups in birth weight, gestational age, or other demographic or perinatal factors. The hematocrit, RBC count, and absolute nucleated RBC counts were significantly higher and the platelet counts significantly lower in the polycythemic group. Regression analysis that included Apgar scores and gestational age showed a significant correlation of absolute nucleated RBC count with the polycythemia status only (P =.017).

CONCLUSION

At birth, term AGA polycythemic infants have increased indices of active erythropoiesis. We speculate that this finding is suggestive of subtle fetal hypoxemia.

Erythropoietin in human milk: physiology and role in infant health

Human milk contains substantial concentrations of erythropoietin, a hormone best known for its role in the regulation of erythropoiesis. Recent studies show that erythropoietin receptors are widely distributed in human tissues, including the gastrointestinal tract, endothelial cells, spinal cord, and brain, suggesting that erythropoietin plays a wider role in infant development. Mammary epithelial cells contribute to the production of erythropoietin in human milk, and erythropoietin concentrations appear to rise slowly in human milk during the first few months of lactation. Current data suggest that erythropoietin in human milk may play a pleiomorphic role in erythropoiesis, neurodevelopment, maturation of the gut, apoptosis, and immunity in the infant.

Red cell mass responses to daily erythropoietin and iron injections in the ovine fetus

OBJECTIVE

Anemic ovine fetuses supplemented with intra-amniotic iron undergo rapid expansion of red cell mass. The present study tested the hypothesis that nonanemic fetuses that were supplemented with daily intra-amniotic iron plus intravascular injections of erythropoietin would experience accelerated erythrocyte production.

STUDY DESIGN

Nine late gestation ovine fetuses received 100 to 120 units of erythropoietin intravascularly plus 10 mg of iron intra-amniotically daily for 7 days (low erythropoietin dose group). Four additional fetuses received 1000 units of erythropoietin plus 10 mg iron daily for the same period (high erythropoietin dose group). Responses were compared with 9 nonsupplemented time-control fetuses. Statistical testing was by 3-factor repeated measures analysis of variance.

RESULTS

Immediately after erythropoietin injection, plasma erythropoietin concentration was elevated approximately 25- and 250-fold in the low and high erythropoietin dose groups, respectively. Erythropoietin returned to basal levels by 24 hours after the injection. Plasma iron concentration increased in the low erythropoietin dose group but not in the control or high erythropoietin dose groups. Reticulocyte index increased in both erythropoietin supplemented groups but not in control fetuses. Hematocrit level increased above control by day 5 in the low erythropoietin dose group and by day 2 in the high erythropoietin dose group. Red cell mass increased significantly on supplement day 7 in the low erythropoietin dose group and on day 5 in the high erythropoietin dose group. Fetal blood gases and pH were unchanged with time in all 3 groups.

CONCLUSION

Although daily combined erythropoietin and iron supplements in nonanemic ovine fetuses significantly increased circulating red cell mass in a dose-dependent manner, this increase was small relative to the rapid expansion of red cell mass previously observed after iron supplementation in fetuses with hemorrhage-induced anemia. We speculate that this difference in response may be due to a combination of rapid fetal clearance of erythropoietin plus a relative insensitivity to erythropoietin caused by the absence of other cytokines, which are elevated during fetal anemia.

Erythropoietin responses to progressive blood loss over 10 days in the ovine fetus

Long-term loss of fetal blood can occur with fetomaternal hemorrhage, vasoprevia, or placental previa. Our objective was to determine the effects of progressive fetal blood loss over 10 days on fetal plasma erythropoietin (EPO) concentration and its relationship to arterial PO(2), hematocrit, and the volume of blood loss. Late-gestation fetal sheep (n = 8) were hemorrhaged daily at a rate of 1 ml/min over 10 days. The extent of hemorrhage differed in each fetus and ranged from 30 to 80 ml/day, with the cumulative volume removed ranging from 78 to 236 ml/kg estimated fetal weight. Four fetuses served as time controls. EPO concentration measurements were by radioimmunoassay. Statistical analyses included regression, correlation, and analysis of variance. We found that EPO and arterial PO(2) were unchanged until the cumulative hemorrhage volume exceeded 20-40 ml/kg. Once this threshold was exceeded, plasma EPO concentration increased progressively throughout the study and averaged 14.3 +/- 3.2 times basal values on day 10. EPO concentration, arterial PO(2), and hematocrit changes were related curvilinearly to cumulative hemorrhage volume (P < 0.01), whereas the relationship between plasma EPO and arterial PO(2) was log linear (P < 0.001). We conclude that 1) fetal plasma EPO concentration and arterial PO(2) are insensitive to a slow, mild-to-moderate blood loss over several days; 2) unlike the rapid return of EPO to normal within 48 h after acute hemorrhage, fetal EPO concentration undergoes a progressive increase with moderate-to-severe blood loss over several days; 3) the long-term hemorrhage-induced changes in EPO are best correlated with arterial PO(2); and 4) the fetal EPO response to hemorrhage does not appear to be limited by the fetus's ability to produce EPO.

Neonatal nucleated red blood cell counts in twins

We counted nucleated red blood cells (NRBC) per 100 white blood cells (WBC) in the umbilical cord blood from 98 twins born to 49 women with uncomplicated twin pregnancies at > or = 34 weeks of gestation to better characterize NRBC in twins. Twelve women with monochorionic (MC) placentas and 37 with dichorionic (DC) placentas gave birth at 36.7 +/- .9 and 36.5 +/- 2 weeks of gestation, respectively. All twins were born with an Apgar score of > or = 7 at 1 min. Log10 (NRBC/100 BC) in 98 twins exhibited a nearly normal distribution, and was significantly associated with gestational age for both MC (r = -0.457, p = 0.025) and DC twins (r = - 0.275, p = 0.018), and with birth weight for both MC (r = -0.682, p < 0.001) and DC twins (r = -0.336, p = 0.003). Log10 (NRBC/100 WBC) tended to be larger in smaller twins than in larger twins in the MC group, and significantly larger in smaller twins than in larger twins in the DC group (p < 0.05). Intertwin difference in Log10 (NRBC/100 WBC) was defined as the value of Log10 (NRBC/100 WBC) of the smaller twin minus Log10 (NRBC/100 WBC) of the larger twin, and became greater with increasing intertwin difference in birth weight (r = 0.411, p = 0.003). These findings suggest that neonatal NRBC reflected gestational age and birth weight in twins. This preliminary observation using a small number of twins suggests that the smaller twin may have experienced a relative lack of oxygen compared with the larger twin in utero.

Plasma erythropoietin in newborn lambs

In the present study early postnatal changes in erythropoietin (Epo) level and hemoglobin concentration in 8 lambs were examined. Plasma Epo was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human Epo. In all the lambs, except one, Epo was low, or undetectable, immediately after birth. Within 6-12 h after birth, a marked increase in plasma Epo was found in 4 of the lambs. Within 3-7 days after birth, Epo was back to low levels. In the lamb with high Epo levels at birth, drastic decreases were observed during the next 6 h. There was no obvious correlation between the hemoglobin concentrations and the changes in plasma Epo.

Effect of passive smoking in pregnancy on neonatal nucleated red blood cells

OBJECTIVE

We evaluated whether the absolute nucleated red blood cell (RBC) count is elevated in term, appropriate for gestational age (AGA) infants born to women exposed to passive smoking in pregnancy.

PATIENTS AND METHODS

We compared absolute nucleated RBC counts taken during the first 12 hours of life in 2 groups of term, vaginally delivered infants, 1 group born to mothers who were routinely exposed to tobacco smoke during pregnancy (n = 55) either at home or at the workplace, and the other to mothers who were not routinely exposed to any tobacco smoke (n = 31). We excluded infants of women with conditions known to elevate nucleated RBC counts.

RESULTS

There were no differences between groups in birth weight, maternal age, gravidity, parity, maternal analgesia during labor, 1- and 5-minute Apgar scores. Gestational age was minimally higher in the control group (39.6 +/- 1.1 vs 39.2 +/-.8 weeks). The median absolute nucleated RBC count in the passive smoking group was 357 x 10(6)/L (range: 0-5091 x 10(6)/L) versus 237 x 10(6)/L (range: 0-1733 x 10(6)/L) in nonsmoking controls. Stepwise regression analysis that included Apgar scores, gestational age, and the passive smoking status (yes/no) as independent variables showed significant correlation of absolute nucleated RBC count only with the passive smoking status.

CONCLUSION

At birth, term AGA infants born to mothers exposed to passive smoking have increased circulating absolute nucleated RBC counts compared with those of controls. We speculate that passive smoking in pregnancy should be avoided, because it may have subtle negative effects on fetal oxygenation.

Fetal erythropoietin levels in pregnancies complicated by meconium passage: does meconium suggest fetal hypoxia?

OBJECTIVE

We sought to determine whether umbilical cord plasma erythropoietin levels were different in deliveries complicated by meconium passage and to determine whether this response is influenced by gestational age.

STUDY DESIGN

Fetal erythropoietin levels were measured in 203 appropriately grown neonates at 37 to 43 weeks of gestation; among those, 70 had passed meconium.

RESULTS

Meconium passage in the entire population was associated with elevated fetal erythropoietin levels (68 vs 31 mIU/mL; P <.001). Cord blood gases, pH, base deficit, and PO (2), as well as the 1- and 5-minute Apgar scores, were not different between the meconium and no-meconium groups. Gestational age and birth weights were significantly higher in the meconium group. Stepwise multiple regression analysis with meconium and gestational age used as the independent variables showed both meconium and gestational age to be independently associated with fetal erythropoietin levels (r = 0.356, F = 14.5; meconium, P <.001; gestational age, P <.01).

CONCLUSIONS

These results suggest that meconium passage can be associated with chronic fetal hypoxia as demonstrated by elevated fetal erythropoietin levels, independent of gestational age.

Adaptive responses during anemia and its correction in lambs

There is limited information available on which to base decisions regarding red blood cell (RBC) transfusion treatment in anemic newborn infants. Using a conscious newborn lamb model of progressive anemia, we sought to identify accessible metabolic and cardiovascular measures of hypoxia that might provide guidance in the management of anemic infants. We hypothesized that severe phlebotomy-induced isovolemic anemia and its reversal after RBC transfusion result in a defined pattern of adaptive responses. Anemia was produced over 2 days by serial phlebotomy (with plasma replacement) to Hb levels of 30-40 g/l. During the ensuing 2 days, Hb was restored to pretransfusion baseline levels by repeated RBC transfusion. Area-under-the-curve methodology was utilized for defining the Hb level at which individual study variables demonstrated significant change. Significant reciprocal changes (P < 0.05) of equivalent magnitude were observed during the phlebotomy and transfusion phases for cardiac output, plasma erythropoietin (Epo) concentration, oxygen extraction ratio, oxygen delivery, venous oxygen saturation, and blood lactate concentration. No significant change was observed in resting oxygen consumption. Cardiac output and plasma Epo concentration increased at Hb levels <75 g/l, oxygen delivery and oxygen extraction ratio decreased at Hb levels <60 g/l, and venous oxygen saturation decreased and blood lactate concentration increased at Hb levels <55 g/l. We speculate that plasma Epo and blood lactate concentrations may be useful measures of clinically significant anemia in infants and may indicate when an infant might benefit from a RBC transfusion.

Use of recombinant human erythropoietin (EPO-alfa) in a mother alloimmunized to the Js(b) antigen

Erythropoietin (EPO) is a glycoprotein hormone and the principal regulator of erythropoiesis in the fetus, newborn, and adult. EPO-alfa is erythropoietin manufactured by recombinant human DNA technology (rhEPO). After counseling, a pregnant woman with anti-Js(b) in her serum was started on rhEPO (600 U/Kg, biweekly) to prevent anemia secondary to serial donations of her blood for fetal transfusions. After a total of 25 rhEPO infusions and autologous donation of 8 units of whole blood, maternal hemoglobin prior to the elective cesarean section at 37 weeks was 11.3 gm/dL. Serum EPO concentration was determined in paired maternal and fetal blood samples, before ultrasound guided intravascular transfusions, in this alloimmunized Js(b)-negative and another Rh(D) alloimmunized pregnancy to determine possible correlations between maternal and fetal serum EPO. rhEPO prevented anemia in a patient who donated 8 units of blood from 18-37 weeks of pregnancy without inducing adverse biological effects such as hypertension or thrombotic complications in the placenta. Data presented in this study suggest that EPO does not cross the human placenta.

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.

Correlation of neonatal nucleated red blood cell counts in preterm infants with histologic chorioamnionitis

OBJECTIVE

The aim of this study was to compare the neonatal nucleated red blood cell counts in preterm infants in the presence and absence of clinical and histologic chorioamnionitis while controlling for gestational age and birth weight percentile.

STUDY DESIGN

Nucleated red blood cell counts were obtained from preterm infants delivered after preterm labor or preterm premature rupture of membranes. Patients were divided on the basis of clinical and histologic chorioamnionitis. Nucleated red blood cell counts between groups were compared, and regression analysis controlling for gestational age and birth weight percentile was performed.

RESULTS

Of 359 patients, both measures of infection status were significantly associated with increased nucleated red blood cell counts. In the regression analysis histologic chorioamnionitis retained significance, whereas clinical chorioamnionitis did not.

CONCLUSIONS

Histologic chorioamnionitis produces an erythropoietic response in the fetus. Whether fetal erythropoiesis is a direct response to mediators of inflammation or whether it is the result of a rise in erythropoietin is unknown.

Erythropoietin (Epo), protein and iron supplementation and the prevention of anaemia of prematurity: effects on serum immunoreactive Epo, growth and protein and iron metabolism

The effect of recombinant human (r-Hu) erythropoietin (Epo) (300 IU/Kg per week for 4 weeks) was studied in healthy preterm infants (n = 14) fed human milk with additional milk protein and high doses of iron. The controls (n = 15) were in themselves a study group and were used to follow the natural course of anaemia of prematurity on such nutrition. Serum immunoreactive Epo (SiEpo) increased significantly 24 h after r-HuEpo injections (range 36 to > 128 mU/ml) and remained at these levels throughout the treatment period. r-HuEpo in such moderate doses kept haemoglobin above 11 g/dl. Bodyweight gain, protein and iron parameters indicated adequacy of dietary protein and iron. In controls, siEpo increased during the first weeks after nutritional supplementation, with a concommitant rise in reticulocyte count. At age 3 weeks, despite low siEpo levels, reticulocyte counts indicated active erythropoiesis. Following further moderate increases in siEpo, the reticulocyte count increased to high levels (7%). The reticulocyte response suggests that erythropoiesis in preterm infants is less dependent upon Epo levels than in adults.

Biochemical monitoring of fetal distress with serum-immunoreactive erythropoietin

The ability of parameters like umbilical arterial pH and Apgar score to predict and/or to reflect fetal distress are limited. It is known that erythropoietin (EPO) increases when partial pressure of oxygen is insufficient for metabolic demand. Therefore we studied the levels of EPO in the cord blood of stressed neonates (n = 75). In addition, reference values for EPO were established in a group of healthy term infants (n = 54) (mean +/- SD: 20.02 +/- [mU/ml]) and in premature infants (n = 77) according to gestational age. A significant increase in EPO concentrations was found in the stressed group: 153.4 +/- 418.8 [mU/ml], p < 0.003 (n = 27) in acute stress; and 102.6 +/- 127.1 [mU/ml], p < 0.002 (n = 48) in chronic stress. However parameters like hemoglobin, hematocrit, umbilical arterial pH and Apgar-score did not correlate with EPO values. A sensitivity of 59% and a specificity of 92% was calculated. We conclude that serum EPO concentrations are capable of detecting acute and chronic stress and could be useful as a screening method. In part EPO concentrations also allow us to grade stress in pregnancies that are complicated by diseases like preeclampsia.

Umbilical vein oxygen tension independent from gestational age at birth

Umbilical venous oxygen tension (UVPO2) and gestational age are negatively correlated antepartum. To see if the negative correlation between UVPO2 and gestational age would still be present postpartum, a retrospective study of all 7522 births at the University of Zurich Hospital from 1989 through 1992 was performed. The 6612 infants with UVPO2 values were divided into low and higher risk groups. Singletons between the 10th and 90th weight percentiles, born vaginally with cephalic presentation after spontaneous onset of labor from healthy mothers were considered low risk. All other births were considered higher risk. No correlations between UVPO2 and gestational age were found in any group studied (low risk, higher risk or total population). The higher risk group had a lower mean UVPO2 than the low risk group (p < .0001). Since there is a negative correlation before birth and none after birth, this indicates that some preterm infants may be subject to greater drops in UVPO2 during delivery than term infants. The magnitude of the drop increases with additional complications and immaturity. However, not all preterms have normal UVPO2 values for gestational age antepartum. Some preterms already have a low UVPO2 in utero and experience a drop in UVPO2 during delivery as well.

Doppler flow velocimetry of the splenic artery in the human fetus: is it a marker of chronic hypoxia?

OBJECTIVE

The aim of this investigation was to describe splenic artery flow velocity waveforms in the appropriate- and small-for-gestational-age human fetus.

STUDY DESIGN

Splenic artery flow velocity waveforms were prospectively obtained from 95 appropriate- and 15 small-for-gestational-age fetuses with pulsed Doppler ultrasonography. The resistance index was used to quantify the Doppler waveform.

RESULTS

A second-degree polynomial model expressed the changes of the resistance index in appropriate-for-gestational-age fetuses with advancing gestation (y = 0.057x [Weeks] - 0.001x2, r = 0.53, p < 0.001). In 14 of 15 (93%) small-for-gestational-age fetuses the splenic artery resistance index was below the mean for gestational age. In five of 15 (33%) small-for-gestational-age fetuses the resistance index of the splenic artery was < 2 SEMs. A trend toward a higher hematocrit was noted in the five fetuses with splenic artery resistance index values < 2 SEMs (50.2%) compared with other small-for-gestational-age fetuses (43.0%).

CONCLUSION

Our results suggest that some small-for-gestational-age fetuses have decreased resistance at the level of the splenic artery. We postulate that the increased erythropoietin level, stimulated by hypoxia, results in decreased resistance at the level of the splenic artery in small-for-gestational-age fetuses. Finally, management of the small-for-gestational-age fetus may be aided by the study of the splenic artery waveforms.

The ontogeny of the biological role and production of erythropoietin

In has been long recognized that erythropoiesis in adults is under control of erythropoietin, a glycoprotein produced mainly by adult kidneys in inverse relation to oxygen availability. Increasing evidence indicates nowadays that EPO is also an essential growth factor for red cell precursors at different sites of fetal erythropoiesis. The primary site of EPO production during fetal and neonatal life is the liver, and the fetus has been shown to be able to increase EPO production in response to hypoxia through intrinsic oxygen sensing mechanisms of hepatocytes. Thus despite different sites of both erythropoiesis and EPO production a similar oxygen dependent feedback control of red cell formation appears to operate during all stages of development. EPO levels in fetal blood are potentially useful parameters of fetal stress, and, as in adults, the availability of recombinant EPO raises the possibility to modulate erythropoiesis in the perinatal period.

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).

Lack of transport of erythropoietin across the human placenta as studied by an in vitro perfusion system

The transfer of human recombinant erythropoietin (rhEPO) from the maternal to the fetal side was investigated using the technique of in vitro perfusion of an isolated cotyledon of human placenta, with recirculation of the perfusate (130 ml) in separate closed maternal and fetal circuits. rhEPO (221-512 U), together with [14C]BSA (bovine serum albumin, 44.8 kBq or 2,688,000 dpm), was added to the maternal circuit only. Despite a considerably lower molecular weight of EPO (mol. wt. = 30,400 Da) compared to BSA (mol. wt. = 69,000 Da), no difference was found in their transfer across the placenta from the maternal to the fetal side, which was very low for both macromolecules. The total transfer of rhEPO derived from the concentration measured in the samples taken from the fetal circuit at the end of 4-5 h of perfusion, was in the range of 0.04% of the amount initially added to the maternal compartment. A similar amount of transfer was determined for [14C]BSA (0.04-0.07%, n = 12). In conclusion, by direct determination in a dually in vitro perfused human placental cotyledon, no significant transfer of rhEPO from the maternal to the fetal side could be shown.

Cord blood erythropoietin in the presence and absence of labor in normal infants

To evaluate erythropoietin (Ep) levels in normal labor and cesarean section we studied the cord serum of 111 term pregnancies, divided into three groups: (i) those born by normal vaginal delivery (n = 69); (ii) those delivered vaginally from mothers who were smokers (n = 20); and (iii) those delivered by elective cesarean section (n = 22). The three groups did not differ in maternal age, gestational age, birthweight, infant sex and Apgar scores. No correlation was found between Ep and hematocrit in all three groups of normal terms studied. Although not statistically significant the lower mean Ep value observed in cesarean section compared with the values obtained from normal deliveries could suggest that the process of labor may be a cause of these differences.

Interleukin-3, interleukin-6, granulocyte-macrophage colony-stimulating factor and erythropoietin cord blood levels of preterm and term neonates

The cascade of known haematopoietic growth factors controlling granulomonopoiesis and erythropoiesis includes interleukin-3 (IL-3), interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), and erythropoietin (EPO). Elevated endogenous IL-3 and IL-6 cord blood levels in infection-free premature and mature neonates may reflect their possible role for expansion of haematopoietic progenitor cells, granulocytes and monocytes. Within the erythroid lineage a synergistic action of IL-3, IL-6 and EPO can be assumed. To identify the regulatory role in fetal haematopoietic expansion cord blood plasma levels of these haematopoietic growth factors were assessed in 19 premature and 20 mature infants using commercial enzyme-linked immunosorbent assay and enzyme-amplified sensitivity immuno assay test kits. Peripheral blood IL-3, GM-CSF and EPO were studied in 5 and 10 premature infants respectively. Compared with cord blood levels we found a decline in EPO levels but no decrease of IL-3 and GM-CSF during the 1st month of life. We conclude that postnatal decrease in plasma burst-promoting activity levels in preterm infants is mainly explained by low postnatal EPO levels.

Lack of associations between fetal and maternal serum-erythropoietin at birth

Erythropoietin (EPO) is known to be the main regulator of erythropoiesis. We wanted to determine whether EPO production during pregnancy takes place independently in the mother and the fetus, and to identify the factors which set the EPO level. Endogenous EPO levels were determined in simultaneous samples from the umbilical vein, the umbilical artery and a maternal vein in 126 mother-child pairs and simultaneously from amniotic fluid (n = 14) in unselected births. Results were related to clinical and biochemical parameters of fetal well-being, mode of delivery, duration of labor, and infant parameters at birth. There was a weak correlation between maternal and fetal log EPO values (umbilical vein: r2 = 0.11; umbilical artery: r2 = 0.08), but a highly significant correlation between log EPO levels in the two umbilical vessels (r2 = 0.91) and between both umbilical blood and amniotic fluid (r2 = 0.41). Maternal EPO levels were lower than fetal levels in 76 cases, higher in 47, and nearly identical in 3. Increased fetal EPO levels were associated with clinical and biochemical indicators of fetal stress. These associations help to explain why EPO concentrations in fetal blood are independent of maternal levels and also indicate that EPO does not cross the placental barrier. These findings are discussed in the light of the animal experimental and in vitro evidence for placental transfer of EPO. Our data, and the work of others, make such a transfer in humans quite unlikely. This observation has therapeutical consequences for the treatment of maternal anemia with recombinant human EPO.

Effect of intravenous beta-sympathomimetic tocolysis on human fetal serum erythropoietin levels

OBJECTIVE

The major stimulus for erythropoietin production is tissue hypoxia. We sought to investigate the relationship of beta-sympathomimetic administration for tocolysis and fetal serum erythropoietin.

STUDY DESIGN

Umbilical cord blood was obtained from infants whose mothers received intravenous beta-sympathomimetic tocolysis and who were delivered at < or = 34 weeks' gestation. Serum erythropoietin was measured by radioimmunoassay. On the basis of the presumed 2- to 4-hour half-life of fetal erythropoietin, the infants were divided into two groups. In group 1 (n = 16) beta-sympathomimetic therapy was discontinued < 24 hours before delivery; in group 2 (n = 11) it was discontinued > or = 24 hours before delivery.

RESULTS

Group 1 fetuses had significantly higher erythropoietin levels than did group 2 fetuses (37.3 vs 13.9 mU/ml, p = 0.02). The duration of beta-sympathomimetic tocolysis and the maximum infusion rate were not different. The two groups did not differ in gestational age, birth weight, route of delivery, presence of labor, or duration of first or second stage of labor.

CONCLUSIONS

We speculate that intravenous beta-sympathomimetic tocolytic therapy stimulates fetal erythropoietin production by decreasing fetal oxygenation as a result of the reversible fetal metabolic effects of the tocolysis. These data suggest that beta-sympathomimetic tocolysis should be undertaken cautiously if fetal compromise is suspected, fetal well-being should be assessed carefully if tocolysis is undertaken, and treatment should be discontinued promptly if a clear benefit is not realized.

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.

Neonatal polycythemia in appropriately grown infants of hypertensive mothers

Neonatal polycythemia is a frequent finding after pregnancies complicated by diabetes and by maternal hypertension with intrauterine growth retardation (IUGR). It is still unclear if the association of polycythemia with hypertension is the result of IUGR or of hypertension per se. To establish the incidence of neonatal polycythemia in populations at risk, we analyzed the results of hematocrit values obtained from 1592 neonates born consecutively at the Hospital de Clinicas, Buenos Aires. Capillary hematocrit values were obtained by heel stick before 6 h of age. When the values were 65% or greater, new samples were obtained from an antecubital vein. The risk of polycythemia in appropriately grown infants of hypertensive mothers was 12.6-fold greater than the risk in the general population. These data show that maternal hypertension poses a significant risk for polycythemia, regardless of fetal growth. We suggest that, to prevent possible sequela, hematocrit is measured routinely in all infants of hypertensive mothers for prompt diagnosis and treatment.

Is fetal insulin secretion affected by fetal hypoxia?

Fifty-five pregnant Rhesus isoimmunized women were subjected to fetal blood sampling or fetal blood transfusion on 135 occasions. Glucose and C-peptide concentrations were measured in fetal blood, in addition to the routine investigations for complete blood count, blood gases and lactate concentration, in order to investigate whether fetal insulin secretion was affected by hypoxia from fetal anemia. We found a strong relation between the concentration of C-peptide and gestational age at sampling (r = 0.53, P less than or equal to 0.000001). Multiple regression analysis also demonstrated that glucose (P less than or equal to 0.0051) and lactate (P less than or equal to 0.0003) also affected the concentration of C-peptide. We were unable to find any relation between C-peptide concentrations and blood gas variables. We conclude that fetal insulin secretion, measured as C-peptide concentration in fetal blood, is not affected by hypoxia from anemia as long as hemoglobin concentration remains within the range 2.1-14.8 g/dl).

Direct relationship of antepartum glucose control and fetal erythropoietin in human type 1 (insulin-dependent) diabetic pregnancy

In the present study the antepartum relationship between maternal diabetic glucose control and fetal hypoxaemia was examined in 44 Type 1 (insulin-dependent) diabetic and 23 non-diabetic control pregnancies. Maternal HbA1C was used to assess maternal integrated blood glucose control while fetal metabolic control was evaluated by antepartum glucose, insulin, and C-peptide determinations in amniotic fluid at elective caesarean delivery. Fetal hypoxaemia was assessed indirectly by fetal umbilical vein plasma erythropoietin level at delivery. A prospectively developed statistical pathway model was used to examine the relationship of these variables. In applying forced stepwise multiple regression with this model, we observed in the diabetic subjects that mean maternal HbA1C during the last month of pregnancy correlated significantly with fetal umbilical venous erythropoietin at delivery (r = 0.57, p less than 0.001). Additional significant contributions to umbilical venous erythropoietin were found for amniotic fluid glucose and amniotic fluid insulin when these two independent variables were added in stepwise fashion (p less than 0.01). We conclude that in diabetic pregnancy, antepartum control of maternal hyperglycaemia is a significant factor associated with fetal hypoxaemia. We speculate that this effect is mediated through perturbations which accelerate fetal metabolism and which is expressed by amniotic fluid levels of glucose and insulin.

Serum immunoreactive erythropoietin of children in health and disease

Serum immunoreactive erythropoietin (siEPO) was determined in cord serum from neonates (n = 97, gestational age 36-43 weeks), in healthy children from birth to adolescence (n = 260) and in children with haematological (n = 30), renal (n = 10) and congenital heart diseases (n = 70). In healthy children siEPO levels decreased after birth (geometric mean cord siEPO 35.6 mU/ml with 95% range of 17-56 mU/ml in eutrophic, nondistressed fetuses) and reached lowest values during the first 2 months (geometric mean siEPO 11.5 mU/ml). Thereafter siEPO levels increased slightly and were constant between 2 months and adolescence. The geometric mean siEPO for healthy children after birth was 18.8 mU/ml with 95% range of 7-47 mU/ml. These estimates were not significantly different from normal adult values. In newborns with fetal distress (n = 15) cord siEPO was significantly elevated (geometric mean 63.0 mU/ml; P less than 0.001). In children with haematological disease, siEPO and Hb concentration were inversely correlated (log siEPO (mU/ml) = 4.1-0.20 x Hb (g/dl); r = -0.62; P less than 0.0005). This relationship was significantly different in children with chronic renal failure (log siEPO (mU/ml) = 0.67 + 0.035 x Hb (g/dl); r = 0.50; P = 0.1). In children with heart disease the geometric mean siEPO was 19.2 mU/ml with 95% range 8-65 mU/ml for cyanotic (SaO2 less than 94%) and 17.7 mU/ml with 95% range of 12-36 mU/ml for acyanotic patients. In this group siEPO values were inversely correlated to the arterial oxygen content (log siEPO (mU/ml) = 1.61-2.04 x oxygen content (l/l); r = -0.28; P less than 0.02).

Incidence, neutrophil kinetics, and natural history of neonatal neutropenia associated with maternal hypertension

Neutropenia occurs often among the newborns of women with hypertension, but its cause, mechanism, and clinical consequences have not been adequately studied. Of 72 infants whose mothers had hypertension during pregnancy, 35 (49 percent) had neutropenia, which persisted from 1 hour to 30 days. The disorder was more prevalent among newborns whose growth had been retarded in utero (P less than 0.01), those who had been delivered prematurely (P less than 0.001), and those whose mothers had had severe hypertension (P less than 0.002) or hypertension and the HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets) (P less than 0.01). Kinetic investigations of circulating, marginated, storage, and proliferative neutrophils and their progenitors suggested that the neutropenia was the result of diminished neutrophil production. Noscomial infections occurred during the first 2 1/2 weeks of life in eight (23 percent) of the newborns with neutropenia, but in only one (3 percent) of those without this disorder (P less than 0.01). We conclude that the neonatal neutropenia associated with maternal hypertension is due to transiently reduced neutrophil production and is associated with an increased risk of noscomial infection. Its basic cause 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.

Fetal cord blood's potential for bone marrow transplantation

Approximately 18 years ago, the authors were able to produce an apparently successful bone marrow transplant by using umbilical cord blood. In view of the Chernobyl disaster and the subsequent problems of treatment with marrow transplantation, this study undertook to explore further the potential use of umbilical cord blood as a source of marrow cells. Specimens of umbilical cord blood were collected from 13 routine obstetrical deliveries. All specimens grew erythroid and granulocytic-monocytic colonies. The formation of these various hematopoietic colonies from umbilical cord blood was at least equivalent to bone marrow, and in some instances over 5 times more effective. There appeared to be a statistically significant correlation between the numbers of colony-forming units (CFU-E) and the male infants. The weight of the infants also showed a statistically significant correlation with the burst forming units, erythroid (BFU-E) and the granulocytic-monocytic colony (CFU-GM). The BFU-E also appeared to be greater in number when the time between collection and plating was shorter.

Antenatal fetal heart rate variation in relation to the respiratory and metabolic status of the compromised human fetus

Three groups of women were delivered by caesarean section before labour: for an abnormal fetal heart rate (FHR) trace (21 cases, group 1), or for maternal deterioration in severe pre-eclampsia without gross fetal heart rate abnormalities (20 cases, group 2), or to avoid mechanical difficulties in labour at term (30 cases, group 3). The mean gestational ages of the first two groups were 32 weeks with a high proportion of infants small-for-gestational-age. In group 1, FHR variation (mean range of pulse intervals) was less than half (20.6 SE 1.2 ms) of the normal value at the same age (44.4 SE 1.5 ms). This was associated with hypoxaemia (mean umbilical artery PO2 of 6 mmHg at delivery), with evidence of compensation shown by an elevated amniotic fluid erythropoietin. The fetuses were hypoglycaemic and had greater umbilical artery blood alanine concentrations, but no large changes in adenine nucleotide or endorphin plasma concentrations. Although there was a minor degree of respiratory acidaemia at birth, there was not significant metabolic acidaemia. The results demonstrate that the reduced variation of 'suboptimal' and 'decelerative' fetal heart rate records is associated with fetal hypoxaemia and evidence of nutritional deprivation, but not with asphyxia.

Serum immunoreactive erythropoietin in healthy normal children

To provide reference data for normal children, serum immunoreactive erythropoietin (siEp) was estimated by radioimmunoassay in samples from 130 healthy children, 57 girls and 73 boys, with ages between 1 month and 16 years. In 128 of the children the (geometric) mean siEp was 15.8 miu/ml (iu: international units) with 95% range (the range within which 95% of the observations are predicted to fall) 9.1-27.6 miu/ml. There was no relation between siEp and the variables haemoglobin (Hb), PCV, age and sex. There were two outliers, both girls, aged 9.5 and 9.8 years, in whom siEp was greater than 256 miu/ml. In both, Hb and PCV were normal and we are unable to account for these atypical findings. Estimates of siEp in the 128 children were not significantly different from those in 22 healthy adults investigated simultaneously (mean 16.2 miu/ml, with 95% range 11.2-23.3 miu/ml).