Anemia Defisiensi Besi pada Kehamilan

01Pathophysiology

Pregnancy induces a state of physiologic hemodilution. Plasma volume expands by approximately 40 to 50 percent, while red blood cell mass increases by only about 20 to 30 percent. This disproportionate expansion causes a relative drop in hemoglobin concentration, even in well-nourished women. The nadir of this physiologic dilution typically occurs around 28 to 34 weeks of gestation. This is why a mildly low Hb in the second trimester does not always indicate pathology, but values falling below 11 g/dL at any point during pregnancy are classified as anemia per WHO and Kemenkes criteria.

Buku Saku Pencegahan Anemia Kemenkes 2023 notes that during pregnancy, the body undergoes enlargement of several organs including the breasts, uterus, and placenta, along with an increase in total blood volume. Combined with fetal growth that accelerates over time, these changes markedly increase the demand for iron, folate, and other nutrients. If dietary intake cannot keep pace, the mother develops a true nutrient-deficit anemia on top of the physiologic dilution.

Iron deficiency is by far the most common cause, accounting for roughly 50 percent of anemia in pregnancy globally and an even higher proportion in developing countries. Iron is needed to synthesize hemoglobin, and during pregnancy the total iron requirement rises to approximately 1,000 mg over the entire gestational period (300 mg for the fetus and placenta, 500 mg for the expanded maternal red cell mass, and 200 mg for basal losses). Because most women begin pregnancy with suboptimal iron stores, supplementation is given as a blanket approach without checking anemia status first, as the Buku Saku Pencegahan Anemia Kemenkes 2023 explicitly recommends. The rationale cited is that with a 48.9% prevalence of anemia in Indonesian pregnant women, and an even larger proportion having depleted iron stores without overt anemia, universal supplementation is both safe and cost-effective.

At the cellular level, iron deficiency impairs hemoglobin production in developing erythroblasts, yielding smaller, paler red blood cells (microcytic, hypochromic). With fewer oxygen-carrying molecules per cell, oxygen delivery to tissues falls. The body compensates through increased cardiac output (hence palpitations and tachycardia), redistribution of blood flow (hence pallor in less critical vascular beds), and upregulation of 2,3-DPG to shift the oxygen-hemoglobin dissociation curve rightward. When these compensatory mechanisms are overwhelmed, symptoms of tissue hypoxia emerge: fatigue in muscles, poor concentration in the brain, and dyspnea reflecting increased ventilatory drive.

Buku Saku Pencegahan Anemia Kemenkes 2023 emphasizes that anemia develops gradually, allowing the body to adapt so that symptoms are often not noticed until the condition is already moderate or severe. This insidious onset is the reason screening is built into routine antenatal care rather than relying on symptomatic presentation.

Folate deficiency produces a different picture: impaired DNA synthesis leads to megaloblastic erythropoiesis with large, oval macrocytes and hypersegmented neutrophils. Neural tube defects in the fetus are the feared consequence, which is why folic acid (400 mcg) is combined with iron in the standard TTD formulation.

02Classification and Clinical Manifestation

By Severity (WHO)

By Morphology (MCV-Based)

Maternal and Fetal Complications

03Diagnostic Workup

Buku Saku Pencegahan Anemia Kemenkes 2023 stipulates that hemoglobin should be checked at least twice during pregnancy: once in the first trimester and once in the third trimester, integrated into standard ANC visits. This dual-timepoint strategy captures women who enter pregnancy already anemic as well as those who develop anemia as fetal demands peak in the third trimester.

The best initial test is a CBC. In a licensing exam vignette, you will be given a pregnant woman with fatigue and pallor, and the first thing to confirm is the hemoglobin level. A value below 11 g/dL establishes the diagnosis of anemia in pregnancy.

Once anemia is identified, the next step is to characterize it by MCV. A low MCV points toward iron deficiency or thalassemia trait. To distinguish between these two, order a serum ferritin: if ferritin is low, the diagnosis is iron deficiency. If ferritin is normal or high despite a low MCV, consider thalassemia and order hemoglobin electrophoresis. A practical discriminator often tested: in iron deficiency the RDW is elevated (anisocytosis) whereas in thalassemia trait the RDW is typically normal.

If the MCV is high (macrocytic), check folate and B12 levels. The peripheral smear showing hypersegmented neutrophils (five or more lobes) is the classic finding of megaloblastic anemia.

Buku Saku Pencegahan Anemia Kemenkes 2023 adopts a blanket supplementation policy and does not mandate Hb testing before starting TTD, because prevalence is high enough that the population-level benefit outweighs the cost of universal screening. However, for clinical management and exam purposes, Hb measurement remains the cornerstone of diagnosis and monitoring.

04Management and Treatment

All pregnant women in Indonesia receive TTD containing 60 mg of elemental iron and 400 mcg folic acid, one tablet daily, starting as early as possible in pregnancy. Buku Saku Pencegahan Anemia Kemenkes 2023 stresses that this is equivalent to 300 mg of ferrous sulfate heptahydrate, or 180 mg of ferrous fumarate, or 500 mg of ferrous gluconate. This distinction matters because many commercial multivitamins list iron in salt weight rather than elemental weight, leading to underdosing. For example, a tablet containing "60 mg ferrous fumarate" provides only about 10 mg of elemental iron, far below the recommended 60 mg.

Patients should be counseled to take TTD after meals (not on an empty stomach) or at bedtime to minimize gastrointestinal side effects such as nausea, epigastric discomfort, constipation, or diarrhea. Buku Saku Pencegahan Anemia Kemenkes 2023 also recommends taking TTD with plain water and consuming vitamin C-rich foods to enhance absorption. Within two hours before or after taking TTD, patients should avoid tea, coffee, milk, calcium tablets, and antacids, all of which impair iron absorption through chelation or mucosal coating.

Black stools are a normal and expected effect of oral iron supplementation and should not be mistaken for melena. Patients should be reassured about this.

If oral iron is not tolerated or if Hb fails to rise by at least 1 g/dL after 4 weeks of adequate oral therapy, consider parenteral iron. IV iron formulations such as ferric carboxymaltose allow large single-dose infusions and are safe in the second and third trimesters. Parenteral iron is also preferred when there is documented malabsorption or when delivery is imminent and time for oral correction is insufficient.

Blood transfusion is reserved for severe symptomatic anemia or hemodynamic compromise. The threshold is generally Hb < 5 g/dL or clinical instability regardless of Hb level.

Buku Saku Pencegahan Anemia Kemenkes 2023 explicitly addresses several myths that can undermine adherence: that TTD is a "medicine" only for sick people (it is also a supplement for prevention), that TTD raises blood pressure (it does not; iron and folic acid do not affect sodium balance), that TTD causes heavier menstruation (menstrual volume is governed by hormones, not iron), and that TTD makes the baby too large (macrosomia is related to gestational diabetes, not iron supplementation).

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common trap with anemia in pregnancy is confusing physiologic hemodilution with pathologic anemia. A vignette describing a healthy-appearing woman at 28 weeks with an Hb of 10.5 g/dL, normal MCV, and normal ferritin does not require iron therapy beyond routine supplementation. The test-writer is checking whether you know that a modest Hb drop in the second trimester can be physiologic. Conversely, if that same patient has an Hb of 9.5 g/dL with a low MCV and low ferritin, the answer is iron deficiency anemia requiring therapeutic-dose iron.

Another frequent mistake is failing to distinguish iron deficiency from thalassemia trait when both present with microcytosis. The vignette clue is the Mentzer index or, more commonly on exams, the ferritin: low ferritin means iron deficiency, normal or high ferritin with microcytosis means thalassemia. Treating a thalassemia carrier with aggressive iron supplementation is ineffective and can lead to iron overload.

Watch for questions that test timing of supplementation and compliance barriers. Buku Saku Pencegahan Anemia Kemenkes 2023 dedicates an entire section to debunking myths (TTD raises blood pressure, TTD is only needed if you feel sick, TTD causes heavy periods). These appear as patient counseling questions where the correct answer involves reassuring the patient and emphasizing continued use.

Finally, remember the iron absorption interactions. A vignette describing a compliant patient whose Hb fails to improve despite daily iron should prompt you to ask about concurrent intake of tea, coffee, calcium supplements, or antacids, all of which inhibit absorption when taken close to the iron dose. The correct next step is counseling on proper timing (separate by at least 2 hours), not switching to parenteral iron.

The core competency being tested across all anemia-in-pregnancy questions is your ability to integrate epidemiologic context (who is at risk), laboratory interpretation (MCV, ferritin, and smear findings), and stepwise management (prevention, oral therapy, parenteral rescue, transfusion) into a coherent clinical decision.