Early Anemia of Prematurity: Clinical Guidelines

List of Abbreviations

BP – blood pressure

IMV – invasive mechanical ventilation

ABDS – acid-base balance status

HC – healthcare organization

NSG – neurosonography

NEC – necrotizing enterocolitis

HMF – human milk fortifier

VLBW – very low birth weight

NPUDI – neonatal and premature infant pathology department

NICU – neonatal intensive care unit

CBV – circulating blood volume

EAP – early anemia of prematurity

ICU – intensive care unit

US – ultrasound examination

RR – respiratory rate

HR – heart rate

RBCC – red blood cell components

ELBW – extremely low birth weight

EPO – erythropoietin

Hb – hemoglobin

HbA – adult-type hemoglobin

HbF – fetal hemoglobin

Hct, Ht – hematocrit

MCV – mean corpuscular volume

MCH – mean corpuscular hemoglobin

MCHC – mean corpuscular hemoglobin concentration

RBC – red blood cell count

RET-HE – reticulocyte hemoglobin equivalent

SD – standard deviation

Terms and Definitions

Anemia is a hematological syndrome characterized by a decrease in hemoglobin concentration and/or hematocrit by more than 2 standard deviations from the mean hemoglobin and/or hematocrit values for a given postnatal age.

Early anemia of prematurity is an anemia that develops in premature infants at 3–10 weeks of life.

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Early anemia of prematurity is a hematological syndrome characterized by a decrease in hemoglobin and/or hematocrit by more than 2 standard deviations from the mean hemoglobin and/or hematocrit values for a given postnatal age in premature infants, developing at 3–10 weeks of life [1–3].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

Early anemia of prematurity (EAP) has a polyetiological character and is associated with physiological factors caused by prematurity, as well as non-physiological factors, which include post-natal cardiorespiratory disorders, infectious diseases, and iatrogenic factors [4].

Physiological factors associated with prematurity include:

1. Inadequate erythropoietin (EPO) production and low plasma erythropoietin levels [5–8].

In premature infants in the postnatal period, EPO levels are significantly lower than in full-term infants and do not change significantly during the first two months of life [9]. A low response to tissue hypoxia is characteristic of fetuses and premature infants, which is the result of a switch in EPO synthesis from the liver, which is less sensitive to hypoxia, to the kidneys, which are more sensitive to hypoxia [4].

2. Shorter erythrocyte lifespan (30–60 days).

3. Leftward shift of the oxygen dissociation curve as a result of the switch in hemoglobin synthesis from fetal hemoglobin (HbF), which has a high oxygen affinity, to adult hemoglobin (HbA), which has a lower oxygen affinity.

4. Postnatal increase in 2,3-diphosphoglycerate concentration in erythrocytes, facilitating oxygen release from hemoglobin.

5. Adaptive cardiovascular mechanisms compensating for the reduced oxygen transport capacity in anemia.

6. Increase in circulating blood volume due to rapid child growth and weight gain [4].

Postnatal and iatrogenic factors include:

1. Severe respiratory and cardiovascular failure

2. Infectious diseases (early and late neonatal sepsis)

3. Phlebotomy losses.

Phlebotomy blood losses due to the high necessity of laboratory monitoring in premature infants can also contribute to the development of EAP. In premature newborns, especially those with very low birth weight (VLBW) and extremely low birth weight (ELBW), one of the main causes of anemia in the first weeks of life is phlebotomy losses during blood sampling for tests. In the first month of life, in premature infants with a birth weight of less than 1500 grams, phlebotomy losses range from 3.8 to 22 ml/kg/week [10,11].

4. Blood losses due to hemorrhages and bleeding.

5. Inadequate nutrient intake (protein, vitamins, minerals, calories) [4,12].

Iron and vitamin deficiencies in the premature infant's body exacerbate the course of early anemia [13].

1.3 Epidemiology of the Disease or Condition

The highest incidence of clinically significant anemia is observed in neonatal intensive care units, reaching 62–68%.

Anemia most frequently develops in premature infants (70% of the total number of newborns with anemia), especially at a gestational age of 32 weeks and less, as well as in children who underwent surgery for congenital malformations of the gastrointestinal tract and heart, and in patients with generalized congenital infection and neonatal sepsis [1,10].

1.4 Features of Coding the Disease or Condition

P61.2 Anemia of prematurity

1.5 Classification of the disease or condition

There is no separate classification for early anemia of prematurity.

1.6 Clinical presentation of the disease or condition

Clinical symptoms of anemia are non-specific: examination reveals lethargy, poor suckling, skin and mucosal marbling and pallor, combined with various disorders of other organs and systems depending on the cause of the anemia; tachypnea/bradypnea, apnea, need for oxygen therapy, decreased efficacy of ongoing respiratory therapy, leading, among other things, to an increase in mechanical ventilation (MV) parameters; drowsiness or neurological status changes; tachycardia > 180 bpm, heart auscultation may reveal muffled heart sounds and a systolic murmur.

2. Diagnostics, medical indications and contraindications for diagnostic methods

Criteria for diagnosing early anemia of prematurity

The diagnosis of early anemia of prematurity can be confirmed if laboratory diagnostic signs of anemia are detected [14].

The main criteria for diagnosing early anemia of prematurity:

A decrease in red blood cell count, hemoglobin concentration, and/or hematocrit by more than 2 standard deviations from the mean values of red blood cells, hemoglobin, and/or hematocrit for a given postnatal age [1].

Hemoglobin and hematocrit values depending on the postnatal age of the child are presented in Table 1 [15].

Table 1. Hemoglobin, hematocrit, and venous blood erythrocyte values in newborns and infants of the first 6 months of life [14,15] (modified from Dallman P.R. et al., 1977, Girelli G. et al., 2015).

Auxiliary diagnostic criteria for neonatal anemia

Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and reticulocyte counts (normal reticulocyte values in newborns are 0.15–1.5%) [15].

Table 2. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) in newborns and infants of the first 6 months of life (venous blood) [14,15] (modified from Dallman P.R. et al., 1977, Girelli G. et al., 2015).

Early anemia of prematurity is normocytic, normochromic, and hyporegenerative.

Early anemia of prematurity is characterized by a decreased serum erythropoietin concentration with normal levels of ferritin, transferrin, and iron. Reference values for these parameters depend on the type of analyzer used and may slightly vary across different medical organizations.

2.1 Complaints and Anamnesis

Comments: Maternal risk factors for early anemia of prematurity include:

• maternal history of anemia of varying severity before and during pregnancy;

• acute maternal infection during pregnancy or exacerbation of a chronic infection;

• multiple monochorionic pregnancy;

• preeclampsia;

• intrauterine interventions during pregnancy;

Neonatal factors include:

• prematurity;

• low birth weight;

• course of the infectious process;

• phlebotomy losses;

• hemorrhagic syndrome.

2.2 Physical Examination

• A visual therapeutic examination is recommended for a premature infant with suspected anemia [1,16].

GCR CLEL 5Grade of Recommendation C (Level of Evidence - 5)

Comments: See section 1.6 "Clinical presentation"

2.3 Laboratory Diagnostics

• A complete (clinical) blood count with determination of red blood cell count, hemoglobin, and hematocrit evaluation is recommended for a premature infant with suspected anemia to determine further management [15,18–20].

GCR BLEL 3Recommendation Grade B (Level of Evidence — 3).

Comments: It is optimal to use venous blood parameters for a reliable determination of hemoglobin and hematocrit levels, as capillary blood values may be distorted in edema or polycythemia syndrome. The hemoglobin level in capillary blood can be 10 g/L higher than in venous blood.

• To assess gas exchange disorders, signs of tissue hypoxia, metabolic disorders, and to determine further management of symptomatic therapy in a premature newborn with signs of anemia accompanied by respiratory and/or hemodynamic disorders, the following tests are recommended [19–28]:

- acid-base balance (ABB)

BIP CLEL 4Level of evidence C (level of data reliability - 4).

- blood gases

BIP BLEL 3Level of evidence B (level of data reliability - 3).

- blood lactic acid level

LoR CGoE 4Level of Recommendation C (Grade of Evidence - 4).

Comments: determination of blood lactic acid (lactate) level depends on the laboratory capabilities of the medical organization (MO).

• When the development and progression of anemia are suspected in premature newborns for differential diagnosis, it is recommended to perform a reticulocyte count, a general biochemical blood test with determination of iron, ferritin, and transferrin levels [16,29–32].

LeveL of Recommendation BGrade of Evidence 2LeveL of Recommendation B (Grade of Evidence - 2).

Comments: Reference values of these parameters depend on the type of analyzer used and may slightly differ across various medical organizations. It should be kept in mind that serum ferritin is an acute-phase protein; therefore, if the infant has an infectious and inflammatory process, this parameter may show normal or elevated values despite existing body iron deficiency. Conversely, serum transferrin levels may be decreased in the presence of an infectious and inflammatory process in the infant.

A decrease in reticulocyte hemoglobin equivalent indicates latent iron deficiency. The reference values for reticulocyte hemoglobin (RET-HE) in premature infants are 27-34 pg [33,34]. If laboratory diagnostics are available at a specific medical organization, testing for blood erythropoietin levels may be used to diagnose early anemia of prematurity.

• In case of clinical deterioration during and after a blood transfusion, a premature newborn is recommended to undergo evaluation of acid-base balance and blood gases, blood potassium and calcium levels to detect transfusion reactions and transfusion complications [28,35,36].

BIP CLEL 4Level of evidence C (level of data reliability - 4).

Comments: Hyperkalemia is a consequence of erythrocyte hemolysis. If hyperkalemia (6.5-7.0 mmol/L) is detected, the transfusion should be discontinued. Hypocalcemia, metabolic acidosis, or alkalosis are usually associated with citrate intoxication and require timely correction [36].

• Following a blood transfusion in a premature newborn, it is recommended to perform a complete (clinical) blood count and urinalysis no earlier than 2 hours and no later than 24 hours post-transfusion to assess efficacy and detect complications [37].

BIP CLEL 5Level of evidence C (level of data reliability - 5).

Comments: The criterion for transfusion efficacy is the achievement of target hematocrit and/or hemoglobin values in venous blood.

2.4 Instrumental Diagnostics

• To rule out internal organ hemorrhage, a premature newborn showing signs of anemia is advised to undergo ultrasound examinations, including neurosonography (NSG), a comprehensive abdominal ultrasound, as well as an ultrasound of the kidneys and adrenal glands [38–46].

GCR CLEL 4Grade of Recommendation C (Level of Evidence - 4)

2.5 Other Procedures

• During a blood transfusion and for at least 2 hours afterwards, a premature newborn is recommended to undergo monitoring of heart rate, blood pressure, respiratory rate, oxygen saturation, diuresis, urine color, and body temperature to enable the detection of transfusion reactions and complications [47,48].

BIP CLEL 5Level of evidence C (level of data reliability - 5).

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

3.1. Conservative management

Etiotropic and pathogenetic therapy

• A premature newborn with symptoms of anemia and/or a decrease in blood hemoglobin levels to values requiring correction, in order to achieve the target hemoglobin level, is recommended to receive a transfusion of leukoreduced red blood cell components (RBCCs), taking into account the need for respiratory support [49–53].

BIP ALEL 1Level of evidence A (level of data reliability - 1).

Comments: Indications for replacement blood transfusion with leukoreduced red blood cell components in premature newborns are presented in Table 3 [53].

Table 3. Blood hemoglobin levels (g/L) at which RBCC transfusion is recommended in premature infants, depending on their respiratory status and postnatal age (modified from Whyte R., Kirpalani H., 2011) [53].

^★includes all types of respiratory therapy and support for adequate spontaneous breathing, including mask or diffuse oxygen delivery

The recommended hemoglobin levels as criteria for transfusion cannot be applied in cases of major surgical interventions, sepsis, shock, hemorrhage, or symptoms inherent to anemia (tachycardia, tachypnea) [15,54].

A special group consists of newborns with severe cardiorespiratory diseases (congenital heart defects, bronchopulmonary dysplasia, etc.) and infants on extracorporeal membrane oxygenation. For this category of patients, it is advisable to maintain hematocrit at 40% and Hb at 120 g/L in the presence of signs of hemic hypoxia [15,53,55].

The decision to perform elective transfusion should be made taking into account the risk-benefit assessment in comorbid diseases and conditions (e.g., progressive retinopathy, volume overload, active necrotizing enterocolitis, acute kidney injury, etc.).

Potential risks and complications of blood transfusion[56]:

- Transfusion of an incorrect RBCC component (by blood group, Rh factor, etc.);

- Acute / delayed transfusion reaction;

- Transmission of bacterial and viral infections;

- Transfusion-associated graft-versus-host disease – a rare but frequently fatal condition prevented by gamma-irradiation of blood products;

- Immune and non-immune hemolysis;

- Transfusion-related acute lung injury ("TRALI") with the development of respiratory failure;

- TANEC – transfusion-associated necrotizing enterocolitis – enterocolitis developing within 48–72 hours after blood RBCC transfusion;

- Post-transfusion purpura, in which the platelet count drops catastrophically 5–9 days after transfusion;

- Allergic reactions;

- Metabolic disorders (hyperkalemia, hypocalcemia) and blood acid-base imbalance;

- Volume overload;

- Iron overload;

- Apnea;

- Cardiac arrhythmias;

- Seizures;

- Embolism (air / thrombus);

- Hemodynamic disorders;

- Infection;

- Body temperature instability;

- Thrombocytopenia;

- Intraventricular hemorrhage.

• For the correction of anemia in preterm neonates, blood transfusion with leukoreduced red blood cell components is recommended in a volume of 10–20 mL/kg [10,14,57,58].

Level of Evidence BLevel of Confidence 2Level of recommendation B (level of evidence – 2).

Comments: In a preterm neonate without bleeding, the volume of transfused leukoreduced RBCs in standard clinical situations is 15 mL/kg [10,15]. Calculation of the transfused leukoreduced RBCs can also be performed using a formula, in which case the RBC volume may exceed 20 mL/kg [15]:

target Ht – patient's Ht

Blood volume (mL) = ––––––––––––––––––––––– × neonate's blood volume

RBC component Ht

Blood volume of a preterm neonate is 100 mL/kg. Target Ht > 0.35.

To avoid complications of massive blood transfusion, the total RBC volume should not exceed 60% of the circulating blood volume.

The recommended transfusion duration is no more than 4 hours [48,59–61]. Blood transfusion in extremely low birth weight (ELBW) preterm neonates can be performed in 2 doses with a 4-hour interval to reduce circulatory overload and renal dysfunction.

Transfusion should be discontinued if the following adverse reactions occur [59]:

- tachycardia, bradycardia, or arrhythmia;

- tachypnea;

- increase in systolic blood pressure (BP) by more than 15 mm Hg, unless this is a desired effect;

- temperature rise above 38^°C and/or temperature increase ≥ 1^°C;

- cyanosis;

- skin rash, urticaria, hyperemia;

- hematuria/hemoglobinuria;

• For the treatment of early anemia of prematurity, routine administration of other antianemic drugs (ATC code B03XA) is not recommended [62].

GR BLEL 1Grade of Recommendation B (Level of Evidence - 1).

Comments: The group of "other antianemic drugs" (ATC code B03XA) includes the following drugs used in newborns: epoetin alfa** and epoetin beta**. There are also studies on the use of #darbepoetin alfa**(ATC code B03XA) in newborns [62–65]. Treatment regimens with Epoetin alfa** (ATC code B03XA) at a dose of 200 IU/kg three times a week intravenously or subcutaneously until target hemoglobin and hematocrit levels are reached, but for no longer than 6 weeks. The treatment regimen with Epoetin beta** (ATC code B03XA) is at a dose of 250 IU/kg three times a week intravenously or subcutaneously until target hemoglobin and hematocrit levels are reached, but for no longer than 6 weeks. The dosing regimen for #darbepoetin alfa**(ATC code B03XA) is 10 mcg/kg intravenously or subcutaneously once a week [63,66]. When prescribing drugs, one should follow the product labeling. Dosing regimens and routes of administration may differ across instructions from various manufacturers.

When hemoglobin and hematocrit levels normalize, the drug is discontinued.

3.2 Surgical Treatment

Not applicable

3.3 Other Treatment

The therapeutic and protective regimen involves creating optimal conditions for nursing premature newborns.

An important component in the treatment of anemia of prematurity is adequate intake of enteral protein (mother's milk fortified with a fortifier, or dry/ready-to-feed special formula for preterm and low-birth-weight infants) or, in cases of enteral feeding intolerance, parenteral protein of at least 3.5 g/kg/day [69].

4. Medical Rehabilitation and Sanatorium-Resort Treatment

There are no special requirements.

5. Prevention and Dispensary Observation

Prevention

• For prevention of anemia in the newborn, delayed clamping and cutting of the umbilical cord 60–120 sec after birth is recommended in the absence of the need for immediate care of the mother or child [70–72].

GCR ALEL 1Grade of Recommendations A (Level of Evidence – 1)

Comments: An alternative to delayed cord clamping may be umbilical cord milking. Routine use of umbilical cord milking is not recommended due to insufficient evidence of its safety in extremely premature newborns [70].

• To prevent anemia in a premature newborn, it is recommended to minimize phlebotomy blood loss and diagnostic venipunctures [73–76].

GCR ALOE 2Grade of Recommendation A (Level of Evidence – 2)

Comments: a rational approach to ordering additional laboratory blood tests should be followed, using micro-methods to determine the minimum necessary blood parameters and utilizing non-invasive monitoring of blood gas composition and bilirubin levels when feasible in a specific medical institution.

• To prevent anemia of prematurity, routine administration of other antianemic agents (ATC code B03XA) is not recommended for all preterm newborns [60,62].

Strength of Recommendation = BEvidence Level = 1Strength of recommendation B (level of evidence - 1).

Comments: The group of "other antianemic drugs" (ATC code B03XA) includes the following medications used in newborns: epoetin alfa** and epoetin beta**. There are also studies on the use of #darbepoetin alfa** in newborns [62–65]. Regimens for Epoetin alfa** (ATC code B03XA): early administration of #Epoetin alfa** (ATC code B03XA) starting from the 3rd day of life at a dose of 200 IU/kg three times a week intravenously or subcutaneously until target hemoglobin and hematocrit levels are reached, but for no more than 6 weeks. Regimen for Epoetin beta** (ATC code B03XA): starting from the 3rd day of life at a dose of 250 IU/kg three times a week intravenously or subcutaneously until target hemoglobin and hematocrit levels are reached, but for no more than 6 weeks. Dosage regimen for #darbepoetin alfa** is 10 mcg/kg once a week [63,66]. When prescribing medications, one should follow the product insert. Dosage regimens and administration routes may differ in the product inserts of various manufacturers.

When hemoglobin and hematocrit levels normalize, the medications are discontinued.

• For premature newborns with VLBW and ELBW, oral iron(III) preparations (ATC code B03AB) are recommended starting from two weeks of life for the prevention of iron deficiency [31,77–82].

GCR ALeE 1Grade of Recommendation A (Level of Evidence - 1).

Comments: The recommended dose of oral iron(III) preparations (ATC code B03AB) for premature newborns with VLBW and ELBW is 2–3 mg/kg/day. For newborns with a birth weight of 1500–2000 g, supplementation with oral iron(III) preparations (ATC code B03AB) - #iron(III) hydroxide polymaltose complex^** at a dose of 2 mg/kg/day may be recommended starting from 2–4 weeks of life; for newborns with a birth weight of 2000–2500 g, at a dose of 1–2 mg/kg/day starting from 2–6 weeks of life. Treatment may continue up to 6–12 months of life, depending on individual parameters [83].

Therapy with iron(III) preparations (ATC code B03AB) is carried out under the control of blood hemoglobin, erythrocyte, and ferritin levels [83].

The reference blood ferritin level in premature infants ranges from 35 to 300 mcg/L (Table 4).

Table 4. Recommended blood ferritin levels for the diagnosis of iron overload and iron deficiency in children under 2 years of age (modified from Domellöf, 2017) [83].

If blood ferritin levels drop below 35 mcg/L, the iron dose should be increased to 3–4 (maximum up to 6) mg/kg/day for a limited period. Long-term therapy with iron preparations at a dose > 3 mg/kg/day should be avoided due to potential adverse side effects. An increase in blood ferritin levels above 300 mcg/L may occur, inter alia, due to iron overload resulting from multiple blood transfusions. In such cases, iron therapy should be discontinued until blood ferritin levels fall below 300 mcg/L [83].

When administering blood transfusions, therapy with iron(III) preparations (ATC code B03AB) is recommended to be continued in premature infants, excluding cases of concomitant hemolytic conditions. If the infant has hemolytic disorders, it is recommended to withhold iron preparations for 2 weeks during blood transfusion [81].

During therapy with other antianemic agents (epoetin alfa^**, epoetin beta^**, #darbepoetin alfa^**) (ATC code B03XA), the need for iron increases; therefore, when prescribing epoetin alfa**, epoetin beta**, #darbepoetin alfa** (ATC code B03XA), the recommended dose of trivalent iron preparations (ATC code B03AB) is up to 6 mg/kg/day [83,84].

Iron deficiency during critical periods of early postnatal brain development can have adverse consequences for the neuropsychological development of a preterm infant. However, when prescribing oral trivalent iron preparations (ATC code B03AB), one should not forget about the side effects and the risk of iron overload. Side effects of oral trivalent iron preparations (ATC code B03AB) include vomiting, diarrhea, constipation, and other gastrointestinal disorders. Excess iron can have a negative impact on neuropsychological development; furthermore, free serum iron is a potentially strong oxidizing agent that contributes to oxidative lung and retinal damage in preterm neonates [77,80,81].

• For preterm infants, routine administration of vitamin E (ATC code A11HA03) for the prevention of early anemia of prematurity is not recommended [85–87].

LeveL of Recommendation BGrade of Evidence 2LeveL of Recommendation B (Grade of Evidence - 2).

Comments: Preterm infants, especially those with VLBW and ELBW, have a vitamin E deficiency at birth. However, adequate nutrition (parenteral/enteral) makes it possible to achieve threshold serum vitamin E levels within the first 6 weeks of life [85]. Literature data also indicate the effect of supplemental vitamin E on reducing hemolysis and increasing red blood cell counts and hemoglobin levels in preterm infants [86]. When using high doses of trivalent iron preparations (ATC code B03AB) (6 mg/kg/day), typically with epoetin alfa**, epoetin beta**, #darbepoetin alfa** (ATC code B03XA), there is a high risk of iron free-radical peroxidation, combined with depleted vitamin E stores in the first 2 weeks of life, thereby triggering a cascade of negative effects from iron-induced oxidative stress and hemolysis. Thus, supplemental administration of #vitamin E (ATC code A11HA03) at a dose of 5 IU/day during the period of high-dose iron therapy is justified [88].

Folic acid**.

The physiological requirement for folic acid and its derivatives (ATC code B03BB) in preterm infants receiving enteral nutrition is 35–100 mcg/kg [89].

It has now been established that preterm infants have an adequate supply of folic acid and its derivatives (ATC code B03BB) if their mothers received folic acid** supplements (ATC code B03BB) during pregnancy and the infants received optimal parenteral and enteral nutrition [90–93]. With modern feeding regimens, there is no risk of developing a deficiency of folic acid and its derivatives (ATC code B03BB) in preterm infants, whereas uncontrolled supplemental administration of folic acid** (ATC code B03BB) can lead to excessive intake and overly high blood concentrations in preterm infants [89].

Dispensary follow-up (Active surveillance)

All preterm infants, after discharge, should be monitored by a pediatrician during the first year of life as a risk group for the development of anemia. The frequency of examinations depends on the severity of anemia (Table 5).

Table 5. Frequency of hematological examination depending on blood hemoglobin levels in the outpatient setting.

It should be remembered that an important component of follow-up care for preterm infants with anemia is adequate nutrition in accordance with modern principles of feeding preterm infants [94].

• For extremely preterm neonates, the administration of oral trivalent iron preparations (ATC code B03AB) is recommended on an outpatient basis to prevent iron deficiency [31,82,94,95].

LeR ALoE 1Level of Evidence Recommendation A (Level of Evidence - 1).

Comments: The daily iron requirement for ELBW infants on enteral feeding is 2–3 mg/kg/day[96]. On an outpatient basis, breastfed infants who do not receive human milk fortifier (HMF) need iron supplementation with trivalent iron preparations (ATC code B03AB) at a dose of 2–3 mg/kg/day up to 6 corrected months of age or until the introduction of complementary foods or iron-fortified formulas. Formula-fed infants who do not receive iron-fortified formulas should receive supplementation until the introduction of complementary foods. Longer use of trivalent iron preparations (ATC code B03AB) is indicated for children with low serum iron and ferritin levels (Table 4). Infants receiving a specialized preterm formula or HMF who have normal blood iron and ferritin levels do not require additional prophylactic supplementation with trivalent iron preparations (ATC code B03AB). If iron deficiency anemia develops, the infant should receive trivalent iron preparations (ATC code B03AB) at a therapeutic dose of 4–6 mg/kg/day, depending on the severity of the anemia.

• For a preterm infant with a treatment-refractory hematological symptom complex of anemia or a clinical and hematological symptom complex of progressive anemia on an outpatient basis, an initial or follow-up primary care recommendation includes an evaluation (examination, consultation) by a pediatric hematologist [17].

GCP CLEL 5Level of Evidence C (Level of Likelihood of Evidence - 5).

6. Organization of Medical Care

Blood transfusion in neonates is performed in an inpatient setting.

Indications for discharging a patient from a medical organization:

1. Stable satisfactory condition of the child

2. Stabilization of laboratory parameters and absence of indications for blood transfusion

3. Absence of contraindications for discharge

7. Additional Information

The prognosis of the disease in the absence of comorbidities is generally favorable. Depending on the severity of the anemia, severe damage to internal organs is possible, in particular acute kidney injury. The prognosis depends on comorbidities.

Differential diagnosis should be performed with the following diseases and conditions:

• Anemias of other etiologies: congenital and acquired anemias resulting from reduced erythropoiesis; anemias resulting from increased destruction of erythroid cells; anemias resulting from blood loss.

Criteria for Evaluating the Quality of Medical Care

References

Appendix A1. Working Group Composition

1. Ekaterina N. Balashova – Candidate of Medical Sciences, Leading Researcher at the Prof. A.G. Antonov Department of Anesthesiology and Intensive Care, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Associate Professor at the Department of Neonatology, Member of the Council of the Russian Society of Neonatologists

2. Nikolay N. Volodin, Academician of the RAS, Professor, Doctor of Medical Sciences; President of the Association of Specialists in Perinatal Medicine, Healthcare Provision for Pregnant Women, Fetuses, Newborns, and Children under 3 Years of Age (ASPM+)

3. Dmitry N. Degtyarev – Doctor of Medical Sciences, Professor, Deputy Director for Research, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Head of the Department of Neonatology, Pediatric Faculty, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Council of the Russian Society of Neonatologists

4. Anna V. Degtyareva – Doctor of Medical Sciences, Professor, Head of the Pediatrics Department, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Council of the Russian Society of Neonatologists

5. Viktor V. Zubkov – Doctor of Medical Sciences, Director of the Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Council of the Russian Society of Neonatologists

6. Oleg V. Ionov – Doctor of Medical Sciences, Head of the Prof. A.G. Antonov Department of Anesthesiology and Intensive Care, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), President of the Russian Society of Neonatologists

7. Anna L. Karpova – Candidate of Medical Sciences, Head of Neonatal Inpatient Unit, City Clinical Hospital No. 67 named after L.A. Vorokhobov of the Moscow Healthcare Department, Associate Professor at the Professor V.V. Gavryushov Department of Neonatology, Russian Medical Academy of Continuous Professional Education of the Russian Ministry of Health, Assistant at the Department of Outpatient Therapy, Clinical Laboratory Diagnostics and Medical Biochemistry, Institute of Professional Education, Yaroslavl State Medical University of the Russian Ministry of Health, Member of the Council of the Russian Society of Neonatologists.

8. Anna R. Kirtbaya – Doctor of Medical Sciences, Head of Clinical Work at the Prof. A.G. Antonov Department of Anesthesiology and Intensive Care, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Russian Society of Neonatologists

9. Anna A. Puchkova – Candidate of Medical Sciences, Head of Clinical Work at the Consultation and Diagnostic Center, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Member of the Russian Society of Neonatologists

10. Andrey Yu. Ryndin – Candidate of Medical Sciences, Senior Researcher at the Prof. A.G. Antonov Department of Anesthesiology and Intensive Care, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Associate Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Council of the Russian Society of Neonatologists

11. Olga I. Sapun – Head of the Neonatal Intensive Care Unit No. 2, Children's Regional Clinical Hospital, Krasnodar, Chief Freelance Neonatologist of the Ministry of Health of Krasnodar Krai, Member of the Council of the Russian Society of Neonatologists

12. Olga A. Senkevich – Doctor of Medical Sciences, Professor, Head of the Department of Pediatrics, Neonatology and Perinatology with a Course of Emergency Medicine, Institute of Continuing Professional Education and Accreditation, Far Eastern State Medical University of the Russian Ministry of Health, Member of the Council of the Russian Society of Neonatologists

13. Marina V. Narogan – Doctor of Medical Sciences, Leading Researcher at the Department of Pathology of Newborns and Preterm Infants No. 1, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Professor at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Council of the Russian Society of Neonatologists

14. Diyana R. Sharafutdinova – Candidate of Medical Sciences, Anesthesiologist-Intensivist at the Prof. A.G. Antonov Department of Anesthesiology and Intensive Care, Institute of Neonatology and Pediatrics, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Russian Ministry of Health, Assistant at the Department of Neonatology, N.F. Filatov Clinical Institute of Child Health, I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University), Member of the Russian Society of Neonatologists

No conflict of interest.

Appendix A2. Methodology for Developing Clinical Guidelines

Methods used for collecting/selecting evidence: electronic database search.

Description of methods used for evidence collection/selection: the evidence base for the recommendations included publications from the Cochrane Library, PubMed, EMBASE and MEDLINE, Scopus, Web of Science, e-library, clinicaltrials.gov, electronic libraries, and clinical guidelines published by The National Institute for Health and Care Excellence, The European Association of Perinatal Medicine, The European Society for Pediatric Research, The European Foundation for the Care of Newborn Infants, and The European Society for Neonatology. The literature search depth was 48 years.

Methods used for assessing the quality and strength of evidence:

· expert consensus;

· significance assessment according to the rating scheme.

Scales for assessing levels of evidence (LE) (Tables 1, 2) for diagnostic, preventive, therapeutic, and rehabilitation methods (diagnostic, preventive, therapeutic, rehabilitation interventions) with definitions, and the scale for assessing grades of recommendation (GR) (Table 3) for preventive, diagnostic, therapeutic, and rehabilitation methods (preventive, diagnostic, therapeutic, rehabilitation interventions).

Methods used for analyzing evidence:

· reviews of published meta-analyses;

· systematic reviews with evidence tables.

Description of methods used for analysis of evidence.

When selecting publications as potential sources of evidence, the methodology used in each study was reviewed to ensure its validity. Methodological evaluation was based on questions focused on study design features that significantly affect the validity of the results and conclusions.

To minimize potential subjective errors, each study was evaluated independently by at least two members of the working group. Any discrepancies in assessments were discussed by the full working group. If consensus could not be reached, an independent expert was involved.

Economic analysis:

Cost analysis was not performed, and pharmacoeconomic publications were not evaluated.

Method of guidelines validation:

· external peer review;

· internal peer review.

Description of the guidelines validation method:

The preliminary version of these guidelines was reviewed by independent experts who were asked to comment primarily on whether the interpretation of the evidence underlying the recommendations was accessible and understandable.

Comments were received from primary care physicians and district pediatricians regarding the clarity of the recommendations and their assessment of importance as a working tool in daily practice.

The draft version was also sent to a non-medically trained reviewer to obtain comments from a patient perspective.

Comments received from experts were carefully systematized and discussed by the chair and members of the working group. Each point was discussed, and resulting modifications to the guidelines were recorded. If no changes were made, the reasons for declining the changes were recorded.

Consultation and peer review:

Recent changes to these recommendations are presented for discussion as a draft version. The updated version for wide discussion was posted on the websites of the Russian Society of Neonatologists (RSN) www.neonatology.pro, www.raspm.ru, and https://portalcr.minzdrav.gov.ru/ so that all interested parties have the opportunity to participate in the discussion and improvement of the recommendations.

The draft guidelines were reviewed by independent experts who were asked to comment primarily on the clarity and accuracy of the interpretation of the evidence base underlying the recommendations.

For the final revision and quality control, the recommendations were re-evaluated by the members of the working group, who concluded that all comments and feedback from the experts had been taken into account and the risk of bias in the development of the recommendations was minimized.

Target audience for these clinical guidelines:

1. Neonatologists

2. Anesthesiologists-intensivists

3. Pediatricians

4. Obstetricians-gynecologists

Table 1.Levels of Evidence (LoE) grading scale for diagnostic methods (diagnostic interventions)

Table 2.Levels of Evidence (LoE) grading scale for prevention, treatment and rehabilitation methods (preventive, therapeutic, and rehabilitative interventions)

Table 3. Scale for grading grades of recommendation (GR) for prevention, diagnostic, treatment, and rehabilitation methods (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines

The mechanism for updating clinical guidelines provides for their systematic revision—at least once every three years or upon the emergence of new information on patient management tactics for a given disease, but no more frequently than once every 6 months. The decision to update is made by the Russian Ministry of Health based on proposals submitted by professional medical non-profit organizations. The proposals formed must take into account the results of a comprehensive evaluation of drugs and medical devices, as well as the results of clinical approbation.

Appendix A3. Reference Materials

These clinical guidelines have been developed taking into account the following regulatory and legal documents:

1. Federal Law No. 323-FZ of November 21, 2011, "On the Fundamentals of Protecting the Health of Citizens in the Russian Federation."

2. Russian Ministry of Health, Order No. 203n dated May 10, 2017, "On Approval of Criteria for Assessing the Quality of Medical Care".

3. International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) (World Health Organization), 2019 version.

4. Nomenclature of Medical Services (Ministry of Health and Social Development of the Russian Federation), 2020.

5. Order of the Ministry of Health of the Russian Federation No. 1170n dated October 28, 2020, "On approval of the rules for providing medical care to the population in the profile 'transfusiology'"

(Registered on November 27, 2020, No. 61123)

6. Decree of the Government of the Russian Federation No. 797 dated June 22, 2019, "On approval of the Rules for procurement, storage, transportation, and clinical use of donor blood and its components and on invalidating certain acts of the Government of the Russian Federation"

7. Methodological letter "Resuscitation and stabilization of newborn infants in the delivery room". Ed. by Baybarina E.N. Moscow: Russian Ministry of Health; 2020.

8. Procedure for providing medical care in the profile "Neonatology" (Order of the Ministry of Health of the Russian Federation No. 921n dated November 15, 2012).

9. List of vital and essential medicines for 2020 (Order of the Government of the Russian Federation No. 2406-r dated October 12, 2019).

Appendix B. Physician Action Algorithms

Appendix C. Patient Information

Anemia is common in premature newborns. Anemia is characterized by a significant decrease in the amount of hemoglobin in the baby's blood, as well as the number of red blood cells—erythrocytes. At the same time, the primary function of red blood cells—transporting oxygen to tissues and organs—is impaired. In anemia, oxygen starvation of the baby's organs and systems occurs, which can lead to irreversible health consequences. The development of anemia in an infant is preceded by maternal anemia during pregnancy, poor nutrition, diseases, late gestosis, as well as premature birth, multiple pregnancy, and low birth weight. The frequent development of anemia can be explained by low iron stores, a shorter lifespan of erythrocytes, and immaturity of the hematopoietic organs in a premature infant, which are very sensitive to external and internal pathological factors and cannot rapidly restore blood hemoglobin and erythrocytes. In such cases, newborns develop so-called early anemia of prematurity. Anemia can accompany kidney, liver, and digestive tract diseases, immune disorders, blood loss, and infectious diseases. As can be seen, anemia can develop as a result of various diseases or pathological conditions in the infant. As a result of anemia, the child develops generalized hypoxia, i.e., insufficient supply of oxygen to organs and tissues, including the brain, which can lead to serious consequences for the baby's health. Anemia in children has the following signs: pale skin and mucous membranes, shortness of breath, tachycardia, and poor weight gain. Newborns with severe anemia may require treatment and monitoring in a neonatal intensive care unit, respiratory therapy, and cardiotonic therapy. To diagnose anemia in an infant and determine the causes that caused it, a detailed blood test and instrumental examination methods are performed. The treatment of anemia depends entirely on the form of the disease and the causes that triggered the anemia. Medications for treating anemia are recommended by a physician, depending on the severity and form of anemia in the child. Premature newborns born at a gestational age of less than 31 weeks may be prescribed recombinant human erythropoietin therapy—epoetin alfa** or epoetin beta** (ATX code B03XA), as well as trivalent iron preparations (ATX code B03AB). In severe anemia, children may need a transfusion of erythrocyte-containing blood components. Prenatal prevention of anemia involves monitoring the course of pregnancy and proper maternal nutrition. Therefore, an expectant mother should diversify her diet with foods rich in iron, vitamins, and minerals. Starting from the second half of pregnancy, it is worth discussing the possibility of taking iron supplements (ATX code B03A) with a physician, especially if the pregnancy is not the first or is a multiple pregnancy. To prevent anemia in a newborn immediately after birth, "milking" or delayed cord clamping is performed. Proper feeding of newborns and establishing a daily routine are also necessary. The most easily digestible iron is found in breast milk. Premature infants are at high risk for developing iron deficiency. Therefore, they are recommended to take trivalent iron preparations (ATX code B03AB) during the first year of life. After discharge, it is necessary to monitor the levels of hemoglobin, iron, ferritin, and transferrin in order to select the optimal dose of iron supplements, taking into account the physician's recommendations.

Premature infants require a lot of time for treatment and recovery. It is very important to maintain a positive attitude and support breastfeeding—these two factors are the key to success.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Not applicable.