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Key words: ANEMIA IN PREGNANCY: … - acog anemia in pregnancy treatment


Key words: ANEMIA IN PREGNANCY: …-acog anemia in pregnancy treatment

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Abstract
Screening recommendations for anemia during pregnancy, etiologies of inherited and noninherited forms of anemia,
their impact on maternal-fetal outcomes, and the clinical management of pregnant patients presenting with these
conditions are reviewed. Anemia during pregnancy can cause adverse perinatal outcomes including preterm labor,
premature rupture of membranes, and increased maternal and fetal mortality. Physiologic (dilutional) anemia and iron
deficiency anemia are the two most common noninherited forms of anemia, and some cases may be the result of an
underlying comorbidity such as diabetes or lupus. Aplastic anemia and autoimmune hemolytic anemia are uncom-
mon forms of noninherited anemias that also merit discussion. Inherited forms of anemia include sickle cell disease,
alpha-thalassemia, and beta-thalassemia. Timely diagnosis and treatment of anemia during pregnancy, whether
inherited or noninherited, is imperative to protect mother and baby from potential adverse outcomes associated with
these conditions.
Key words: Anemia; Iron deficiency; Pregnancy; Sickle cell anemia; Thalassemia.
ANEMIA IN PREGNANCY:
SCREENING AND CLINICAL
MANAGEMENT STRATEGIES
Angela Y. Stanley, DNP, MA, FNP-BC, PHCNS-BC, NEA-BC, RNC-OB, C-EFM,
Jerrol B. Wallace, DNP, MSN, CRNA, FAANA, Andrea M. Hernandez, CNM, WHNP, and Jenna L. Spell, PharmD
1
ccording to the World Health Organization (WHO), approximately 40% of pregnancies
worldwide are complicated by anemia (WHO, 2021). Data on anemia for pregnant women
in the United States are limited. Adebisi and Strayhorn (2005) estimated a prevalence of
21.55 per 1,000 women when using a classification of hemoglobin concentration less than
A0 grams per deciliter. Prevalence of anemia among pregnant women has steadily increased from
9.1% (2004) to 11.5% (2019; World Bank Group, 2021).
The oxygen carrying protein hemoglobin (Hgb) is vital to the sustainment of life and is a neces-
sity for the pregnant patient. To manufacture the vital hemoglobin protein, the body must pull
iron molecules from stores in the body. Maternal and fetal outcomes vary according to the moth-
er's hemoglobin and trimester in which anemia is identified. Inherited anemias such as sickle cell
disease and thalassemia inhibit normal production of the hemoglobin protein and may require
complex clinical management. Noninherited anemias in pregnancy are most commonly classified
as physiologic (dilutional) or iron deficiency anemia (IDA) but also include aplastic anemia and
autoimmune hemolytic anemia. The purpose of this article is to provide a review of screening
recommendations, causes of anemia, and clinical management of these conditions.
Screening Recommendations
The American College of Obstetricians and Gynecologists (ACOG, 2021a) recommends that all
pregnant women be screened for anemia in their first trimester using a complete blood cell count
(CBC). Based on result of initial screening, further testing may be needed to provide appropriate
clinical management of subsequent conditions. A second screening should be conducted between 24
and 28 weeks of pregnancy (ACOG). The primary screening tests consist of serum hemoglobin
concentration or hematocrit (ACOG). If IDA is ruled out, the clinician should explore other etiolo-
gies (ACOG). Table 1 reflects the diagnostic values of laboratory tests by trimester for anemia
(ACOG).
A maternal hemoglobin level indicative of anemia requires additional testing for likely etiologies.
Evaluation should include a clinical history as well as laboratory assessment of a CBC and red blood
January/February 2022 MCN 25
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cell (RBC) indices. An RBC and morphology can aid in cat- Noninherited Anemias
egorization of anemia. Mean corpuscular volume (MCV) is Physiologic Anemia
the average volume measurement of erythrocytes. The MCV The most common form of anemia in pregnancy is physi-
is often decreased in microcytic anemias such as iron defi- ologic (dilutional) anemia. Normal physiology of preg-
ciency or thalassemias and increased in macrocytic anemias nancy creates a dilutional anemia secondary to the in-
caused by folate and vitamin B12 deficiency. Mean corpus- creased blood volume and increased RBC mass (Blackburn,
cular hemoglobin is the hemoglobin concentration per RBC 2021). Although RBC production increases during preg-
count, whereas the mean corpuscular hemoglobin concen- nancy, there is a decrease in both hemoglobin and hemato-
tration (MCHC) is the hematocrit divided by hemoglobin. crit values during pregnancy because plasma volume in-
These values will typically be decreased in microcytic ane- creases faster and more than RBC mass (ACOG, 2021a;
mias and increased in macrocytic anemia (Williamson et al., Blackburn, 2021; Horowitz et al., 2013). As an expected
2011). Ferritin is a protein that stores and releases iron, physiologic adaptation, during singleton pregnancy, ma-
therefore, serum ferritin levels reflect amount of iron stored ternal blood volume increases approximately 40% to
in the body for use in the production of hemoglobin. Serum 50%, whereas total RBC mass increases approximately
ferritin is the recommended laboratory test to confirm iron 15% to 20% (ACOG). This blood volume expansion sup-
deficiency in pregnancy due to the high sensitivity and high ports normal fetal growth and development and antici-
specificity of the test (Achebe & Gafter-Gvili, 2017). WHO pated blood loss at birth (ACOG; Vricella, 2017). Despite
(2011) recommends monitoring of ferritin concentration as being a part of normal pregnancy physiology, it's impor-
a way of monitoring the impact of interventions on iron tant to distinguish between physiologic anemia and other
status. Iron deficiency is the only known etiology of low fer- causes.
ritin levels, thus highlighting the utility of this test (Auerbach
& Landy, 2021). Typically, ferritin levels between 30 and 40
ng/mL are associated with chronic disease processes such as
diabetes mellitus and systemic lupus erythematosus. If ferri- The two most common causes of anemia
tin levels are borderline, iron studies including serum iron, in pregnancy are iron deficiency and acute
total iron binding capacity, and transferrin saturation should
be evaluated (Auerbach & Landy). blood loss.
26 volume 47 | number 1 January/February 2022
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Iron Deficiency Anemia causes of iron malabsorption include the following con-
In the United States, overall iron deficiency prevalence in ditions--celiac disease, gastrectomy, gastric bypass sur-
pregnancy is near 18%, with anemia affecting 5% of preg- gery, and Helicobacter pylori (Lopez et al., 2016). Other
nant women (Cantor et al., 2015). Iron deficiency during malabsorptive causes include inflammatory bowel dis-
pregnancy is associated with low birthweight, preterm birth, eases such as ulcerative colitis or Crohn's disease or pica
perinatal mortality, and postpartum depressions (ACOG, syndrome (Camaschella). Nurses should be aware of
2021a). Hemoglobin levels less than six grams per deciliter chronic blood loss disorders that could also lead to IDA.
(g/dL) have been associated with poor fetal outcomes, in- Digestive tract disorders such as esophagitis, gastritis,
cluding death (ACOG). peptic ulcers, diverticulitis, tumors, hemorrhoids, or par-
Iron is a component of hemoglobin in RBCs and is nec- asitic infestation (especially in children) can all cause
essary for the functioning of cellular mechanisms includ- chronic blood loss. Other causes of chronic blood loss
ing DNA synthesis. On average, 20 to 25 mg of iron is include heavy menses, hematuria, hemodialysis, or causes
needed daily for these processes (Lopez et al., 2016). of intravascular hemolysis, that is, damaged heart valves,
There are two forms of dietary iron. Heme iron is found malaria. Chronic diseases such as chronic heart failure,
in animal foods such as meat, poultry, and seafood. Non- cancer, kidney disease, obesity, and rheumatoid arthritis
heme iron is found in plant and dairy foods and makes up can also be risks for IDA. Environmental causes include
the bulk of consumed iron. However, nonheme iron is not poverty, malnutrition, or insufficient dietary intake of
as readily absorbed as heme iron and requires acid diges- iron. Phylates found in cereals can inhibit iron absorp-
tion for bioavailability (Killip et al., 2007). Dietary intake tion; however, ascorbic acid (Vitamin C) and muscle tis-
averages 1 to 2 mg per day. As daily loss (via perspiration, sue improve absorption of iron (Lopez et al.). Many drugs
urinary excretion, and other processes) equals the average can be factorial in IDA including nonsteroidal anti-
daily dietary intake, the body relies upon iron stores and inflammatory drugs, glucocorticoids and salicylates (in-
its iron-recycling mechanisms for homeostasis. Most of crease blood loss risks), and proton-pump inhibitors (de-
the iron needed for new hemoglobin synthesis comes crease iron absorption).
from recycling of heme from the breakdown of old RBCs. Iron deficiency anemia is never a final diagnosis;
This process is usually efficient, with only small losses, identifying and treating the cause is paramount to pre-
which are replenished by dietary intake. A peptide hor- venting further iron loss and worsening anemia. Aware-
mone, hepcidin, regulates iron homeostasis by binding ness of risk factors and a thorough health history can
with the iron-exporting protein, FPN1 (Lopez et al.). help screen at-risk patients. WHO (2017) recommen-
High expression of hepcidin causes increased binding of dations for the treatment of IDA include increasing
this protein and an inability to export iron from cells, low iron intake by dietary food fortification and iron sup-
expression decreases this protein binding and increases plementation, controlling immunization and infection
plasma iron concentration (Lopez et al.). Hepcidin's ex- control for malaria and parasites (primarily hook-
pression is affected by tissue levels of iron (Lopez et al.). worm), and improving nutritional B12, folate, and vi-
Iron deficiency results when the body's demands for tamin A deficiencies.
iron aren't met by dietary absorption. Camaschella For the treatment of pregnant women with anemia, the
(2015) defines IDA as "depressed levels of total body United States Preventive Services Task Force (2015) report-
iron in the presence of anemia" (p. 1833). It is a hypo- ed that supplementation may improve maternal hemato-
chromic, microcytic anemia characterized by low hemo- logic indices; however, evidence for routine screening and
globin and low MCV, low ferritin, low serum iron, and iron supplementation in prenatal care improving maternal
raised total iron-binding capacity. There are many risk or infant health outcomes is unclear (Cantor et al., 2015).
factors that can lead to IDA. Physiologic, pathologic, ACOG (2021a) recommends screening all pregnant wom-
chronic disease, environmental, genetic, and drug-related en for anemia and that all women diagnosed with IDA to
factors can all influence risk. Physiologic risk factors in- be treated with supplemental iron. Daily iron supplementa-
clude conditions that consume iron stores or require an tion is positively correlated with decreased risk of anemia
increased demand such as rapid growth in infancy or at term gestation (Lopez et al., 2016). As a result, mothers
adolescence, pregnancy, heavy menstrual blood loss, elite who breastfeed are at decreased risk of iron deficiency
athletes, or in persons who regularly donate blood (Cam- compared with pregnant women due to iron concentration
aschella). Pathologic causes include disorders, which lead in breast milk (Lopez et al.). The iron concentration in ma-
to decreased absorption or chronic blood loss. Common ture breast milk is 0.20 to 0.80 mg/L, and most mothers
who breastfeed are amenorrhoeic (Lopez et al.).
Given the worldwide prevalence, nurses will encounter
TABLE 1. CLASSIFICATION OF ANEMIA this disorder in clinical practice. Nurses should be aware
Trimester Hgb Hct that IDA disproportionally affects those of low socioeco-
First

What can you do to prevent anemia in pregnancy?Breastfeed your baby as long as possible. Once upon a time it was believed that breastfed babies needed iron supplements because human milk was low in iron.Use an iron-fortified formula. ...Delay cow’s milk feeding for infants; limit it for toddlers. ...Combine foods wisely. ...Try prune juice as a regular beverage. ...