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ACOG PRACTICE BULLETIN - MedElement - acog anemia in pregnancy treatment


ACOG PRACTICE BULLETIN - MedElement-acog anemia in pregnancy treatment

INTERIM UPDATE
ACOG PRACTICE BULLETIN
Clinical Management Guidelines for Obstetrician-Gynecologists
NUMBER 233 (Replaces Practice Bulletin Number 95, July 2008)
Committee on Practice Bulletins--Obstetrics. This Practice Bulletin was developed by the ACOG Committee on Practice Bulletins
--Obstetrics with the assistance of Maureen Malee, PhD, MD.
INTERIM UPDATE: The content in this Practice Bulletin has been updated as highlighted (or removed as necessary) to reflect
limited, focused changes to provide additional information regarding screening for anemia, intravenous iron supplemen-
tation, and the use of cell salvage.
Anemia in Pregnancy
Anemia, the most common hematologic abnormality, is a reduction in the concentration of erythrocytes or hemoglobin
in blood. The two most common causes of anemia in pregnancy and the puerperium are iron deficiency and acute
blood loss. Iron requirements increase during pregnancy, and a failure to maintain sufficient levels of iron may result
in adverse maternal-fetal consequences. The purpose of this document is to provide a brief overview of the causes of
anemia in pregnancy, review iron requirements, and provide recommendations for screening and clinical management
of anemia during pregnancy.
Background suppression, hormone deficiencies, and chronic disease
or infection also may lead to decreased production.
Classification Hemolytic anemias are associated with increased
The definition of anemia recommended by the Centers destruction.
for Disease Control and Prevention (CDC) is a hemoglo- Anemias also may be classified by cell size. In
bin or hematocrit value less than the fifth percentile of the contemporary practice, this typically is done by an
distribution of hemoglobin or hematocrit in a healthy automated cell counter. Macrocytic anemias are associ-
reference population based on the stage of pregnancy. ated with a mean corpuscular volume (MCV) greater
Classification derived from an iron-supplemented popu- than 100 fL. Reticulocytosis also may cause an increased
lation lists the following levels as anemic: hemoglobin MCV. A common cause of macrocytic anemia is folate
(g/dL) and hematocrit (percentage) levels below 11 g/dL deficiency. Microcytic anemias are associated with an
and 33%, respectively, in the first trimester; 10.5 g/dL MCV less than 80 fL. The most common cause of
and 32%, respectively, in the second trimester; and 11 microcytic anemia is iron deficiency. Another common
g/dL and 33%, respectively, in the third trimester (1). cause of microcytic anemia in certain ethnic groups is
Anemias may be categorized by whether they are hemoglobinopathy (2).
inherited or acquired, underlying causative mechanism,
or red blood cell morphology (Boxes 1-3). A mechanis- Anemia in Pregnancy
tic approach categorizes anemias caused by decreased red Pregnancy is associated with physiologic changes that
blood cell production, increased red blood cell destruc- may complicate the diagnosis of hematologic disorders.
tion, and blood loss. Decreased production may result There is an increased iron requirement during pregnancy
from a lack of nutrients, such as iron, vitamin B12, or because plasma volume expands by 40-50%, and eryth-
folate. This lack may be a result of dietary deficiency, rocyte mass expands by 15-25% during a singleton ges-
malabsorption, or bleeding. Bone marrow disorders or tation (3). The greater expansion in plasma typically is
VOL. 138, NO. 2, AUGUST 2021 OBSTETRICS & GYNECOLOGY e55
? 2021 by the American College of Obstetricians
and Gynecologists. Published by Wolters Kluwer Health, Inc.
Unauthorized reproduction of this article is prohibited.
remainder as storage iron. Of the functional iron, more
Box 1. Anemia Classification than 80% is found in the red blood cell mass as hemo-
globin, with the remainder in myoglobin and in respira-
Acquired tory enzymes.
c Deficiency anemia (eg, iron, vitamin B12, folate)
c Hemorrhagic anemia Iron Deficiency Anemia
c Anemia of chronic disease Iron deficiency can be defined as abnormal values on
c Acquired hemolytic anemia biochemical test results, increases in hemoglobin concen-
c Aplastic anemia trations of more than 1 g/dL after iron treatment, or
Inherited absent bone marrow iron stores as determined by a bone
marrow iron smear (1). The spectrum of iron deficiency
c Thalassemias ranges from iron depletion, when stored iron is low, to
c Sickle cell anemia
c Hemoglobinopathies (other than sickle cell anemia) iron deficient erythropoiesis, when both stored and trans-
c Inherited hemolytic anemias port iron are low, to iron deficiency anemia, when stored,
transport, and functional iron are low (1).
reflected by decreases in hemoglobin and hematocrit
Measurements of serum hemoglobin concentration or
hematocrit are the primary screening tests for identifying
levels.
anemia but are nonspecific for identifying iron deficiency.
The total amount of iron in the body is determined
Normal iron indices are listed in Table 1. Laboratory test
by intake, loss, and storage (4). There are approximately
results characteristic of iron deficiency anemia are a
2.3 g of total body iron in women. Additional iron stores
microcytic, hypochromic anemia with evidence of
during pregnancy (approximately 1 g) support this
depleted iron stores, low plasma iron levels, high total
increased red blood cell mass, the fetus and placenta,
iron-binding capacity, low serum ferritin levels, and
and the anticipated blood loss accompanying a vaginal
increased levels of free erythrocyte protoporphyrin.
Measurement of serum ferritin levels has the highest
delivery. When there is adequate iron to meet needs, sensitivity and specificity for diagnosing iron deficiency
more than 70% is classified as functional iron, and the in anemic patients (5, 6). Levels of less than 30 micro-
grams/L confirm iron deficiency anemia (6). The CDC
recommends screening for iron deficiency anemia in
pregnant women and implementing universal iron sup-
Box 2. Anemias Characterized by plementation to meet the iron requirements of pregnancy
Mechanism except in the presence of certain genetic disorders, such
Decreased red blood cell production as hemochromatosis (1, 7). The rationale is that treatment
c Iron deficiency anemia maintains maternal iron stores and may be beneficial for
c Anemia associated with vitamin B12 deficiency neonatal iron stores. The typical diet confers 15 mg of
c Folic acid deficiency anemia elemental iron per day. The recommended daily dietary
c Anemia associated with bone marrow disorders allowance of ferrous iron during pregnancy is 27 mg and
c Anemia associated with bone marrow suppression in lactation it is 9 mg, which is present in most prenatal
c Anemia associated with low levels of erythropoietin vitamins (7). Available iron supplements are listed in
c Anemia associated with hypothyroidism Table 2. Perinatal iron supplementation is important
Increased red blood cell destruction because the typical American diet and endogenous stores
c Inherited hemolytic anemias
are insufficient sources for the increased iron require-
B Sickle cell anemia ments during pregnancy. Sustained-release or enteric-
B Thalassemia major coated preparations dissolve poorly and may be less
B Hereditary spherocytosis effective.
c Acquired hemolytic anemias
B Autoimmune hemolytic anemia Prevalence, Etiologies, and Risk Factors
B Hemolytic anemia associated with thrombotic Limited data are available to estimate the current preva-
thrombocytopenic purpura lence of iron deficiency anemia in pregnant individuals in
B Hemolytic anemia associated with hemolytic
uremic syndrome the United States (8). A national study of anemia in
B Hemolytic anemia associated with malaria pregnancy in the United States found a prevalence of
c Hemorrhagic anemia 21.55 per 1,000 women when anemia was defined as a
hemoglobin concentration less than 10 g/dL (9). The
e56 Practice Bulletin Anemia in Pregnancy OBSTETRICS & GYNECOLOGY
? 2021 by the American College of Obstetricians
and Gynecologists. Published by Wolters Kluwer Health, Inc.
Unauthorized reproduction of this article is prohibited.
prevalence of anemia in pregnancy in non-Hispanic In reproductive-aged women, risk factors for iron
Black women (35.38 per 1,000 women) was two times deficiency anemia include a diet poor in iron-rich foods,
higher than that of non-Hispanic White women (18.02 such as clams, oysters, liver, beef, shrimp, turkey,
per 1,000 women) (9). Teenaged mothers had the highest enriched breakfast cereals, beans, and lentils; a diet poor
prevalence of anemia in pregnancy of all races (9). An in iron absorption enhancers, such as orange juice,
assessment of iron status in pregnant individuals in the grapefruit, strawberries, broccoli, and peppers; a diet
United States using data from the National Health and Nutri- rich in foods that diminish iron absorption, such as dairy
tion Examination Survey (known as NHANES) from 1999 products, soy products, spinach, coffee, and tea; pica
to 2006 found that iron deficiency prevalence increased (eating nonfood substances such as clay or laundry
significantly with each trimester (mean 6 standard error, starch); gastrointestinal disease affecting absorption;
6.9% 6 2.2%, 14.3% 6 2.1%, and 29.5% 6 2.7% in the heavy menses; short interpregnancy interval; and blood
first, second, and third trimesters, respectively) and was loss at delivery exceeding that of an uncomplicated
higher in Mexican American pregnant women, non- vaginal delivery.
Hispanic Black pregnant women, and women with parity Iron deficiency anemia during pregnancy has been
greater than 2 (10). associated with an increased risk of low birth weight,
preterm delivery, and perinatal mortality and should be
treated with iron supplementation in addition to prenatal
vitamins (11, 12). In addition, there may be an associa-
tion between maternal iron deficiency anemia and post-
Box 3. Anemias Classified by Mean partum depression, with poor results in mental and
Corpuscular Volume psychomotor performance testing in offspring (13- 16).
Microcytic (MCV less than 80 fL)
c Iron deficiency anemia Macrocytic Anemia
c Thalassemias Macrocytic anemia may be megaloblastic or nonmegalo-
c Anemia of chronic disease blastic. Causes of megaloblastic anemia include folate
c Sideroblastic anemia and vitamin B12 deficiency and pernicious anemia.
c Anemia associated with copper deficiency
c Anemia associated with lead poisoning Causes of nonmegaloblastic anemia include alcoholism,
liver disease, myelodysplasia, aplastic anemia, hypothy-
Normocytic (MCV 80-100 fL) roidism, and an increased reticulocyte count. Macrocytic
c Hemorrhagic anemia anemia is characterized by an MCV greater than 100 fL.
c Early iron deficiency anemia Levels greater than 115 fL are almost exclusively seen in
c Anemia of chronic disease patients with folic acid or vitamin B12 deficiencies. The
c Anemia associated with bone marrow suppression diagnosis may be confirmed by measurement of serum
c Anemia associated with chronic renal insufficiency folic acid or vitamin B12 levels. Measurement of red cell
c Anemia associated with endocrine dysfunction folate also has been proposed (17). In the United States,
c Autoimmune hemolytic anemia
c Anemia associated with hypothyroidism or macrocytic anemia beginning during pregnancy is over-
hypopituitarism whelmingly caused by folic acid deficiency. It is associ-
c Hereditary spherocytosis ated with diets lacking fresh leafy vegetables, legumes,
c Hemolytic anemia associated with paroxysmal or animal proteins. During pregnancy, folic acid require-
nocturnal hemoglobinuria ments increase from 50 micrograms to 400 micrograms
Macrocytic (MCV greater than 100 fL) per day. Treatment of pregnancy-induced folic acid defi-
ciency should include a nutritious diet and folic acid and
c Folic acid deficiency anemia iron supplementation. Treatment with 1 mg of folic acid,
c Anemia associated with vitamin B12 deficiency administered orally, each day typically produces an
c Drug-induced hemolytic anemia (eg, zidovudine)
c Anemia associated with reticulocytosis appropriate response. Macrocytic anemia in pregnancy
c Anemia associated with liver disease caused by vitamin B12 (cyanocobalamin) deficiency
c Anemia associated with ethanol abuse may be encountered in women who have had a partial
c Anemia associated with acute myelodysplastic or total gastric resection or in women with Crohn disease.
syndrome Women who have had a total gastrectomy require
Abbreviation: MCV, mean corpuscular volume. 1,000 micrograms of vitamin B12, intramuscularly, at
monthly intervals.
VOL. 138, NO. 2, AUGUST 2021 Practice Bulletin Anemia in Pregnancy e57
? 2021 by the American College of Obstetricians
and Gynecologists. Published by Wolters Kluwer Health, Inc.
Unauthorized reproduction of this article is prohibited.

How to prevent anaemia in pregnancy?Encourage breast feeding of infants.Encourage exclusive breast feeding of infants (without supplementary liquid, formula, or food) for 4-6 months after birth.When exclusive breast feeding is stopped, encourage use of an additional source of iron (approximately 1 mg/kg per day of iron), preferably from supplementary foods.More items...