Anemia In Premature Infants Research Articles

Prevention and treatment of anemia of prematurity

Anemia of prematurity is very common in preterm infant.Phlebotomy losses and inadequate production of erythropoietin are the main reasons.Treatment of anemia of prematurity includes delayed umbilical cord clamping at delivery,decreasing phlebotomy losses,use of red cell growth factors such as erythropoietin properly,red blood cell transfusions,which are based on indications and guidelines.In this article we review recent studies in preventing and treating anemia in preterm infants. Key words: Preterm infant; Anemia; Erythropoietin; Transfusions

Evidence for aluminum-binding erythropoietin by size-exclusion chromatography coupled to electrothermal absorption atomic spectrometry

Erythropoietin (EPO) is a glycoprotein that stimulates erythropoiesis and is clinically used for treating anemia during chronic renal failure and for anemia in preterm infants. EPO formulations usually have elevated rates of contamination due to aluminum (Al), which is toxic to both types of patients. Size-exclusion chromatography (SEC) coupled with graphite furnace atomic absorption spectrometry (GF AAS) was employed to separate proteins and to quantify the amount of aluminum present in the elution volume corresponding to EPO and, therefore, to evaluate possible binding. Because EPO formulations contain human serum albumin (HSA), a chromatographic method was optimized for the separation of these proteins. Subsequent to the chromatographic separation, 1-mL fractions of the column effluent were collected, and the Al content in these aliquots was measured by GF AAS. EPO and HSA samples were incubated with Al for 4 h at 4 °C and 37 °C as well as for 16 h at 4 °C and 37 °C. Afterwards, they were injected into the chromatographic system. These samples were also submitted to ultrafiltration (10 and 50 kDa membranes), and Al was measured in the ultrafiltrates. The results showed that Al was present in the eluent volume corresponding to the EPO peak but not in the HSA peak in the chromatograms. Temperature strengthened the interaction because the Al present in the EPO fraction was 3 times higher at 37 °C compared to 4 °C. Thirty-eight percent of the Al present in a 2.4 μg/mL EPO standard solution, and approximately 50% of the Al in formulation samples containing approximately 11 μg/mL EPO and either citrate or phosphate, were non-ultrafiltrable, which suggests that EPO is an effective Al acceptor in vitro.

Blood transfusions increase cerebral, splanchnic, and renal oxygenation in anemic preterm infants

Multiprobe near infrared spectroscopy (NIRS) has been used to study regional cerebral (rSO(2)C), splanchnic (rSO(2)S), and renal (rSO(2)R) tissue oxygenation in newborns. We used this method to study the effects of red blood cell (RBC) transfusions in anemic preterm infants to assess if thresholds for transfusions were appropriate for recognizing a clinical condition permitting tissue oxygenation improvement. Multiprobe NIRS (INVOS 5100, Somanetics) was applied during transfusion to 15 preterm infants with symptomatic anemia of prematurity (hematocrit level of <25%). rSO(2)C, rSO(2)S, and rSO(2)R were recorded at selected times, and then fractional oxygen cerebral extraction ratio [FOEC: (SaO(2)-rSO(2)C)/SaO(2)], fractional oxygen splanchnic extraction ratio [FOES: (SaO(2)-rSO(2)S)/SaO(2)], fractional oxygen renal extraction ratio [FOER: (SaO(2)-rSO(2)R)/SaO(2)], cerebrosplanchnic oxygenation ratio [CSOR: (rSO(2)S/rSO(2)C)], and cerebrorenal oxygenation ratio [CROR: (rSO(2)R/rSO(2)C)] were calculated. In addition, we used Doppler ultrasonography for evaluating cerebral blood flow (CBF), splanchnic blood flow (SBF), and renal blood flow (RBF) velocity. rSO(2)C, rSO(2)S, and rSO(2)R significantly increased during transfusions, while FOEC, FOES, and FOER decreased. CSOR and CROR increased during transfusions. CBF velocity decreased during the study period, while SBF and RBF velocities did not vary. RBC transfusions performed at used thresholds permitted an increase in cerebral, splanchnic, and renal oxygenation. The associated decreases in oxygen tissue extraction might suggest that transfusions were well timed for preventing tissue hypoxia or too early and theoretically prooxidant. Further studies could help to clarify this issue.

Vitamin E Levels during Early Iron Supplementation in Preterm Infants

On the basis of preliminary data, this larger bi-institutional continuation trial evaluating the efficacy and safety of early iron supplementation in preterm infants calls attention to the levels of vitamin E, a marker of antioxidant activity, during iron treatment. A total of 116 preterm infants were randomly assigned to receive at 2 or 4 weeks of age ( N = 62, N = 54, respectively) 5 mg/kg/d of nonionic iron polymaltose complex concomitantly with a daily dose of 25 IU vitamin E (as dl-alpha-tocopherol acetate) from 2 weeks of age. Vitamin E (alpha-tocopherol) levels, iron, ferritin, hemoglobin concentration, and reticulocyte count were recorded from 2 to 8 weeks of age. The morbidities of prematurity associated with free radicals formation were also documented. A gradual increase of alpha-tocopherol levels within physiological range (0.8 to 3.5 mg/dL) was found in the 2-week and 4-week groups during the study period with no difference among the groups ( P > 0.05 for all comparisons). At 8 weeks of age, iron and ferritin levels, hemoglobin concentration, and reticulocyte count were higher in the 2-week group. No correlation was observed between timing of both iron and vitamin E supplement and hemolysis or morbidities associated with prematurity. Thus, treatment of iron with vitamin E supplement at 2 weeks of age is, in our experience, an efficacious and safe treatment for improving anemia in preterm infants.

Effects of erythropoietin on circulating hemotopoietic progenitor cells in premature infants

Objective To study the efficacy and safety of erythropoietin(EPO)in anemic premature infants,and explore the possible mechanism of erythropoietin on premature infants. Methods A randomized controlled study was prospectively conducted.Twenty-four premature infants were divided into treatment and control group with 12 in each.The treatment group received the same treatment as the control group besides receiving EPO 250 U/kg per time,3 times weekly and 4 weeks totally.The number of circulating hematopoietic progenitor cells from 24 premature infants before and two weeks after treatment were determined by semisolid culture technique, and the counts of total white blood cell, neutrophil, lymphoeyte, monocyte,platelet and reticulocyte,hemoglobin were compared between the two groups.ResulIs Compared with the control group.EPO treatment for two weeks did not affect the number of burst forming unit-erythroid,colony forming unit-granulocyte/macrophage,colony forming unit-Mix and colony forming unit-megakaryocyte(P＞0.05),but there was a significant elevation in the number of colony forming unit-erythroid in the treatment group than in the control group(57±20 vs 34±13,P＜0.05).The counts of total white cell,absolute neutrophil,lymphocyte,monocyte and platelet were not significantly decreased between the treatment and control group during the study of 4 weeks(P＞0.05).While all the infants received EPO had higher hemoglobine level and reticulocyte counts after one to four weeks of treatment (P＜0.05).In the fourth week,hemoglobin level of the treatment group was higher than controls [(152±14)g/L vs(128±11)g/L,P＜0.05]. Conclusions EPO is effective and safe for anemic premature infants both on ctinic and hematopoietic progenitor cell level.EPO could improve hemoglobin probably by taking effect on late erythroid progenitor cells and their later stage cells. Key words: Infant,premature,diseases; Anemia; Hemotopoietic stem cells; Erythropoietin

Blood Transfusion Alters the Superior Mesenteric Artery Blood Flow Velocity Response to Feeding in Premature Infants

Packed red blood cell transfusion may increase the risk of necrotizing enterocolitis in premature infants. We hypothesize that the postprandial increase in mesenteric blood flow velocity (MBFV) would not be altered by a blood transfusion in premature infants. Infants born at 25 to 32 weeks and feeding at least 60 mL/kg/d who required a transfusion were randomized within each of two weight strata to feed or not feed during the transfusion. Mean, peak systolic, and end diastolic Doppler MBFV was measured 30 minutes before and after feedings at baseline (anemic) and with the first feeding posttransfusion. Twenty-two infants (27.3 +/- 2.3 weeks' gestational age; hemoglobin [HgB] 9.3 +/- 1.3 g/dL) were studied on day of life 3 to 71 (mean 31.2 days) and a corrected gestational age of 31.8 +/- 2.9 weeks. In the entire cohort, the peak systolic ( P = 0.02) and the mean ( P = 0.01) MBFV increased in response to feeding in the anemic but not the transfused state. On subgroup analysis, only anemic infants > 1250 g ( N = 12, HgB 8.6 +/- 0.9 g/dL) had an increase in peak systolic ( P = 0.04) and mean ( P = 0.006) MBFV with feeding. In conclusion, the MBFV increases in response to feeding in anemic preterm infants > 1250 g. We speculate that the lack of response to feeding in the immediate posttransfusion state may contribute to the development of transfusion-associated necrotizing enterocolitis.

Myocardial Adaptation to Anemia and Red Blood Cell Transfusion in Premature Infants Requiring Ventilation Support in the 1st Postnatal Week

Background: Although transfusion practice in very premature infants is becoming more restrictive, little is known about myocardial adaptation to anemia during the 1st postnatal week. Objectives: To determine the central hemodynamic effects of anemia and red blood cell transfusion in very preterm infants undergoing intensive care. Methods: Twenty-nine neonates of less than 30 weeks gestational age were treated for respiratory distress syndrome, following a strict protocol. Echocardiographies were performed at the 4th and 6th postnatal days, which corresponded to, respectively, just before and 48 h after an erythrocyte transfusion of 15 ml/kg in the 12 anemic infants. Results: Anemic infants had increased stroke volume [2.1 (1.8–2.3) vs. 1.5 (1.3–1.6) ml/kg] and left ventricular (LV) output [312 (271–345) vs. 206 (177–240) ml/min/kg]. The relationship of the heart rate-corrected velocity of circumferential fiber shortening to LV end-systolic meridional wall stress indicated a higher contractile state in the anemic infants, with a higher y-intercept (p = 0.03) and a steeper slope (p = 0.05) of the regression line than in the nonanemic patients. Posttransfusion, the stroke volume, LV output, shortening fraction, and contractile state decreased to the values observed in the nonanemic infants. Conclusions: Myocardial contractility was a major component of the circulatory adjustments in the anemic premature infants requiring ventilation support in the early neonatal period. Changes in LV performance associated with anemia were reversed by transfusion with no detrimental effect on right ventricular function, LV preload or the respiratory status of these patients.

Lack of association between iron status at birth and growth of preterm infants

To assess the association between iron status at birth and growth of preterm infants. Ninety-five premature babies (26 to 36 weeks of gestational age) born from July 2000 to May 2001 in a public hospital in Rio de Janeiro, Southeastern Brazil, were followed up for six months, corrected by gestational age. Iron measurements at birth were available for 82 mothers and 78 children: hemoglobin, hematocrit, mean corpuscular volume and plasma iron. All children received free doses of iron supplement (2 mg/kg/day) during the follow-up period and up to two years of age. Multivariate linear regression analyses with repeated measurements were performed to assess factors associated to linear growth. Growth was more pronounced up to 40 weeks of gestational age, increasing about 1.0 cm/week and then slowing down to 0.75 cm/week. The multivariate analysis showed growth was positively associated with birth weight (0.4 cm/100 g; p<0.001) and negatively associated with gestational age at birth (-0.5 cm/week; p<0.001). There was no association between cord iron and mother iron measurements and growth (p>0.60 for all measures). Only two children had anemia at birth, whereas 43.9% of mothers were anemic (hemoglobin <11 g/dl). Also, there was no correlation between anemia indicators of mothers and children at birth (r<0.15; p>0.20). Maternal anemia was not associated with anemia in preterm infants and iron status of mothers and children at birth was not associated with short-term growth of preterm infants.

Loop diuretics during blood transfusion for anemia in preterm infants

Loop diuretics during blood transfusion for anemia in preterm infants

Effect of Short-Term Erythropoietin Therapy in Anemic Premature Infants

To determine the effectiveness of a 10-day subcutaneous erythropoietin (rHuEpo) course of 300 units per kg per dose plus oral iron compared to oral iron alone in anemic infants during their convalescent phase of illness. Prospective, randomized trial performed at a 40-bed, teaching, referral, level III, neonatal intensive care unit. Infants with a gestational age at birth of less than 32 weeks, hematocrit of less than or equal to 28% with a corrected reticulocyte count of less than or equal to 5%, postconceptual age of less than 48 weeks or 5 months chronological age, and a diagnosis of anemia of prematurity were considered for inclusion. Major outcome parameters included hematocrit, corrected reticulocyte count and red cell transfusion requirements. A total of 60 infants were enrolled (n=30 per group). Infants randomized to rHuEpo had a significantly higher post-treatment hematocrit and corrected reticulocyte count than infants in the iron only group (p<0.001). There was a trend towards fewer red cell requirements in the rHuEpo group. The rHuEpo regimen studied here was associated with an acute improvement in hematocrit and corrected reticulocyte counts. This study did not demonstrate a statistically significant decrease in transfusion therapy, in part related to increased subsequent use of rHuEpo in the control group. Taken together, these data demonstrate that this regimen can effectively treat anemia in convalescent premature infants.

Blood transfusion increases functional capillary density in the skin of anemic preterm infants.

Direct visualization of the microcirculation at the level of the skin capillaries may provide information on the quality of tissue perfusion. Orthogonal polarization spectral imaging (OPS) enables noninvasively direct observation of those blood vessels. OPS was applied to the upper arm of 13 preterm anemic infants [median (95% confidence interval) gestational age: 26 wk (25-26 wk); birth weight: 730 g (652-789 g)] before and 2 and 24 h after transfusion (Tx). OPS images of skin perfusion were continuously recorded on video. Off-line quantitative data of microvascular perfusion were obtained by measuring functional capillary density, vessel diameter, red blood cell velocity, and flow. We found a significant increase in functional capillary density 2 h after transfusion with an additional significant rise after 24 h [before: 142 (134-155); 2 h after Tx: 185 (166-196); 24 h after Tx: 206 (185-219) cm/cm2; p < 0.001), thus indicating improved microvascular perfusion. Vessel diameter, red blood cell velocity, and flow did not change significantly. There were no significant changes in clinical variables, such as blood pressure, heart rate, or body temperature. Whereas conventional monitoring methods did not show any changes after transfusion, quantitative analyses of OPS images indicated improved perfusion; hence, it seems a useful monitor for assessing the response to therapies aimed to improve tissue perfusion.

The efficacy of autologous cord-blood transfusions in neonatal surgical patients

Allogenic blood transfusions have a risk of infection owing to unknown organisms, graft-versus-host reaction, and immunosupression; however, the use of autologous blood has been reported to be safe. Cord blood has been reported to be useful as a source of stem cell transplantation for the treatment of leukemia and genetic disease. Furthermore, autologous cord-blood transfusions (ACBT) have been reported to be effective for the treatment of anemia in premature infants. The authors examined the efficacy of ACBT in neonatal surgical patients. Autologous cord-blood was stored from 12 infants at delivery, including 2 transvaginal and 10 cesarean section deliveries, from 1998 to 2001. All infants had surgically correctable malformations diagnosed antenatally. The mean gestational age was 37.2 +/- 1.6 weeks, and the birth weight was 2,597 +/- 1.6 g. The results of the blood count, serum electrolyte, and liver function tests of the patients who underwent ACBT only (group 1, n = 7) were compared with those of the 7 neonates who underwent an allogenic transfusion during the same period (group 2, n = 7). The mean volume of the stored blood was 64 +/- 35.6 g (range, 20 to 100). Eleven of the 12 patients underwent transfusions. Ten of 11 patients received autologous cord blood. A mean of 44.1 +/- 37.3 g of cord blood was used. Three of 10 cases also required an allotransfusion because of ECMO circuit preparation and a shortage of the stored blood. One patient underwent allotransfusion only. As a result, 7 of 11 babies (64%) who required transfusion were able to avoid an allotransfusion. The blood potassium levels were lower in group 1 than in group 2. No significant complications were recognized clinically. ACBT is considered beneficial because it enables neonatal surgical patients to avoid allotransfusions. Therefore, autologous cord-blood storage should be considered in the patients antenatally diagnosed to have surgical malformations. However, the storage volume varies for each case. Improved techniques to obtain an adequate amount of blood also should be developed.

Iron-Deficient Erythropoiesis in Neonatal Rats

Anemia in premature infants is extremely common. Precise quantitation of iron status and determination of iron incorporation into erythrocytes are important in monitoring therapy for anemia in premature infants, especially when treating with recombinant human erythropoietin (rhEPO). However, the traditional indices of the iron status have limited usefulness in this population. The goal of the current work is to develop an experimental animal model system that addresses the clinical issue relating to quantitation of iron delivery to erythrocytes. We first determined normal hematological values for nontreated, dam-suckled Sprague-Dawley rats by measuring markers of erythropoiesis and iron status during the first 12 postnatal days (PND). The experimental group of rats were administered parenteral rhEpo (430 IU·kg^–1 · day^–1) for 8 days (from PND 4 until PND 12) in the absence (rhEpo^–Fe) or presence (rhEpo^+Fe) of oral iron supplementation (6 mg·kg^–1·day^–1). Rat pups receiving oral iron only (control^+Fe) and pups that were sham fed with the orogastric tube (control^–Fe) were included as controls. Hematological parameters were measured in blood and bone marrow. In a pattern similar to that seen in premature infants during the first 2 months of life, the levels of these hematopoietic markers were dynamic and changed during the first 12 PND. After challenging experimental animals with subcutaneous rhEpo, evidence of iron-deficient erythropoiesis was seen in the rhEpo^–Fe group. Red blood cell levels and absolute reticulocyte counts were higher in both groups receiving rhEpo as compared with the controls. However, the rhEpo^–Fe group experienced a lower hemoglobin level, a lower mean red cell volume, a greater red cell distribution width, and a higher zinc protoporphyrin/heme (ratio than the rhEpo^+Fe group. The neonatal rat is an excellent model of iron-deficient erythropoiesis and will be useful in designing future mechanistic studies examining the interplay between iron and erythropoiesis in the anemic, iron-challenged premature neonate.

La vitamina B12 no modifica la evolución de la anemia del prematuro

The effect of 100 mg IM of vitamin B12, monthly, during 4 months, over anemia in premature infants was evaluated. A controlled, randomized and blinded study in 55 less than 33 weeks of gestational age babies was conduced. There was no differences in hematologyc evolution neither growth in both studied groups. The number of transfusion was significatively lower in both groups than those reported in other studies.

Late-onset neutropenia in very low birth weight infants.

Neutropenia, defined as absolute neutrophil count (ANC) <1500/mm(3), affects 6% to 58% of premature infants in the first week of life. This early-onset neutropenia in premature infants has previously been correlated with sepsis, maternal hypertension, severe asphyxia, and periventricular hemorrhage. Late-onset neutropenia, defined as ANC <1500/mm(3) at a postnatal age of >/=3 weeks, has not been previously reported. The purposes of this study were to determine the prevalence of late-onset neutropenia in very low birth weight (VLBW) infants and to examine the factors that may be associated with this phenomenon. A weekly complete blood cell count (CBC) was performed routinely in all premature infants with birth weight </=1500 g (n = 225) admitted to the neonatal intensive care in a 3-year period who survived until discharge. CBC and differentials were recorded at day 1, day 3, and then weekly until discharge. The clinical data of the study infants were collected by reviewing the medical records retrospectively. Late-onset neutropenia was detected in 51 infants (22%). In both neutropenic (n = 51) and nonneutropenic infants (n = 174), ANC increased postnatally, remained above 5000/mm(3) for the first 3 weeks of life, and had a marked decrease at approximately 4 weeks of age. Thereafter, ANC decreased to a level of approximately 1400/mm(3) in the neutropenic infants and 4000/mm(3) in the nonneutropenic infants. The neutropenic infants had a significantly lower nadir ANC, lower hemoglobin, and higher reticulocyte count than did the nonneutropenic infants with similar platelet counts. None of the study infants received erythropoietin during their hospitalization. This late-onset neutropenia occurred at postnatal age of 6 +/- 2 weeks (range: 3-10 weeks). The duration of neutropenia was 1.7 +/-.7 weeks (range: 1-3 weeks). All of the neutropenic infants had anemia of prematurity with high reticulocyte count and normal platelet count. The neutropenic infants were stable, growing on full oral feedings, and had no signs or symptoms of sepsis. No adverse effects of late-onset neutropenia were apparent in these infants. Late-onset neutropenia is a common incidental finding in stable, growing VLBW infants that has not been previously reported. Late-onset neutropenia is a phenomenon that occurs in anemic premature infants who have marked reticulocytosis. Normal regulation of hematopoiesis is accompanied by a balance between colony-stimulating factors, such as erythropoietin and granulocyte colony-stimulating factor, which regulate erythropoiesis and granulopoiesis. We speculate that imbalance of these factors with increased reticulocytopoiesis in response to anemia of prematurity may explain this phenomenon. We recommend avoiding institution of aggressive, potentially harmful therapy for this phenomenon in healthy, growing VLBW infants.

Supplémentation en fer chez les enfants prématurés traités par érythropoïétine

Anemia in premature infants can be prevented by prophylactic treatment with recombinant human erythroprotein (r-huEPO). r-HuEPO as been used for a long time in patients with end-stage renal failure. The main factor which can limit r-HuEPO efficiency is limited iron bioavailability. Adapted iron supplementation is needed when preterm infants receive r-HuEPO in order to avoid the depletion of iron stores. Oral iron supplementation is simple but indigestibility is frequent. Furthermore, the intestinal absorption and utilization of oral iron is limited. Parenteral iron supplementation is possible in infants who are very pre-term as they are parenterally fed during the first weeks of life. There are various preparations of intravenous iron with different physicochemical properties. Toxicity and side-effects of parenteral iron preparations depend on these properties. Two parenteral iron preparations are available in France: iron-saccharate (Venofer) and iron-dextrin (Maltofer). Iron delivery and possible side-effects of these preparations are different and need to be considered before use in preterm infants.

Erythropoietin to prevent and treat the anemia of prematurity.

Human recombinant erythropoietin was first cloned in 1985, and is currently available for clinical use for a variety of anemias. Following successful clinical trials using erythropoietin to treat adults with the anemia of end-stage renal disease, the first clinical trial evaluating the use of erythropoietin in preterm infants to treat anemia was published in 1990. Since that initial report, numerous clinical trials have reported various levels of success in the treatment of this anemia. Most recently, erythropoietin has been used in the first weeks of life in an attempt to prevent the anemia of prematurity. This review describes mechanisms of erythropoiesis in the fetus and neonate, and focuses on recent clinical trials evaluating the use of erythropoietin to prevent and treat anemia in preterm infants.

Recombinant erythropoietin in treatment of the premature newborn

The many red blood cell transfusions administered to preterm infants as treatment for anaemia are expensive and place them at potential risk from blood-borne infections and other transfusion-related complications. Because plasma erythropoietin concentrations in anaemic preterm infants are reduced relative to anaemic adults, inadequate erythropoietin production has been suggested as an important mechanism for the anaemia these neonates inevitably develop. Despite this justification for the use of recombinant erythropoietin in treating anaemia in preterm infants, erythropoietin therapy is being administered to preterm infants without a clear consensus regarding to which infants, under what conditions, and in what manner it should be applied. This review focuses both on the pathophysiology of anaemia in preterm infants as it relates to the rationale for using erythropoietin to stimulate erythropoiesis for the purpose of reducing red blood cell transfusions and on a critical assessment of the clinical studies employing this therapy.

Iron Nutritional Status Is Improved in Brazilian Preterm Infants Fed Food Cooked in Iron Pots

To determine the efficacy of cooking food in iron pots to prevent anemia in premature infants, a longitudinal study on iron nutritional status was conducted in preterm, healthy infants from families of low socioeconomic level between mo 4 and 12 of life. The infants were divided randomly into two groups. The study group consisted of 22 infants whose food was cooked in iron pots; the control group consisted of 23 infants whose food was cooked in aluminum pots. Supplemental iron [2 mg/(kg⋅d)] was recommended from 15 d to 12 mo of age for both groups. At 12 mo of age, the group fed food cooked in iron pots had significantly better hematologic values than the group fed food cooked in aluminum pots. Differences included hemoglobin (116 ± 16 vs. 103 ± 20 g/L, P= 0.02), hematocrit (0.35 ± 0.04 vs. 0.31 ± 0.05, P= 0.005), mean corpuscular volume (72.1 ± 10.4 vs. 62.7 ± 11.1 fL, P= 0.005), free erythrocyte protoporphyrin (0.78 ± 0.60 vs. 1.46 ± 0.94 mol/L, P= 0.006) and serum ferritin (median 5 vs. 0 g/L, P= 0.001). No significant differences between groups were observed in serum iron concentration, total iron-binding capacity or transferrin saturation. Iron deficiency anemia (hemoglobin ≤ 110 g/L) was observed in 36.4% (8 of 22) of infants in the group fed food cooked in iron pots and in 73.9% (17 of 23) of the infants fed food cooked in aluminum pots (P= 0.03). These results indicate that the iron added to food cooked in iron pots is bioavailable. However, this increased iron availability was insufficient to satisfy the high iron requirements of this group of preterm infants.

Anemia in Preterm Infants

During fetal life, hemoglobin concentration increases from a level of 9 g/dL at l0 weeks' to 14 to 15 g/dL at 22 to 24 weeks' gestation. By the middle of the third trimester, concentrations close to those observed at birth (16 to 17 g/dL) are reached, and little additional change occurs. As a result, cord hemoglobin concentrations in term and preterm newborns are very similar, with the possible exception of the most extremely preterm infants. Immediately after birth, the hemoglobin concentration begins to rise from the combined effects of placental transfusion and the postnatal readjustment of plasma volume. At approximately 8 to 12 hours of life, the hemoglobin plateaus at levels 1 to 2 g/dL above those observed at birth (about 18 g/dL).