Anemia in Pregnancy

Normal physiological hematological changes during pregnancy

• Blood volume- increases, ↑ starts at 6th week.
• Reaches maximum at 32-34 weeks.↑es by 40-50% above the none pregnant state and remains static till term.
• > in multi gravida.
• RBC and Hb – Total red cell mass increases by 20-30%.
• Red cell mass ↑ ses till term.

Classification of anemia during pregnancy

• Physiological anemia of pregnancy.

• Pathological anemia of pregnancy.

1. Deficiency anemia or nutritional anemia
   1. Iron deficiency- microcytic hypochromic anemia.
   2. Folic acid, vitB12 deficiency- megalomaniac anemia
2. Haemorrhagic anemia
   1. Due to acute blood loss eg. Bleeding in early pregnancy
   2. Due to APH
   3. Due to bleeding from GI tract.
   4. Hook worm infestation
3. Hereditary anemia.
   1. Thalassemia.
   2. Sickle cell haemoglobinopathies.
   3. Heamolytic anemia.
4. Bone marrow insufficiency
5. Anemia due to chronic disease eg. Renal or neoplasm.

• Iron deficiency anemia.
  • More than 90% of anemia encountered during pregnancy is due to iron deficiency.
  • Causes of Iron deficiency anemia:
  • Increased demands of iron
  • Diminished intake of iron
  • Repeated pregnancy at short intervals
  • Worm infestation
  • Poor iron store in women entering pregnancy
  • Chronic infection eg. UTI.

• Mild HB 9-10.9 gm%
• Moderate 7-8.9 gm%
• Severe less than 7 gm%

Iron metabolism

• Demand for iron ↑es:
  • To meet the needs of expanding red cell mass.
  • For developing fetus and placenta.
• Total iron required during pregnancy is 700-1400mg,
  • For placenta and fetus 300m
  • For maternal hemoglobin mass expansion 500 mg.
  • 200 mg more are shed through the gut, urine and skin.
  • Rest for blood loss during delivery & purperium.
• Daily requirement of iron is thus 4mg per day.
  • Normal mixed diet supplies about 40 mg of iron each day of which only 1-2mg (5-15%) is absorbed.
• During pregnancy
  • Iron absorption increases.
  • Erythroid hyperplasia.
  • ↑ in unsaturated transferrin concentration. In spite of these changes need of iron cannot be met on by dietary supply alone.

Iron Absorption

• Haem iron
• Proteins
• Meat
• Ascorbic acid
• Fermentation
• Ferrous Iron
• Gastric acidity
• Alcohol
• Low Iron Store
• Increased Erythropoietic activity

• Phytates
• Calcium
• Tannines
• Tea and Coffee
• Herbal Drink
• Fortified Iron Supplements

Erythropoises

• In adults, erythropoiesis in the bone marrow.
• Red blood cells are formed through stages of pronormoblasts – normoblasts – reticulocytes – to mature non-nucleated erythrocytes.
• Average life span of RBC is about 120 days .
• RBC degenerates into haemosiderin and bile pigment.
• Haemoglobin is a conjugated protein
• Contains a globin fraction bound to 4 haem moieties.
• 4 polypeptide changes within the globin fraction.
• Namely alpha, beta , gamma and delta.
• In adult, haemoglobin normally a pair of alpha and a pair of beta chains are present.

Clinical features

• Overt symptoms of iron deficiency are generally not prominent.
• impairment of the function of iron dependent tissue enzymes – impaired function of mitochondria – impaired mental function
• Lethargy and a feeling of weakness.
• Anorexia , indigestion , palpitation, giddiness
• On examination pallor , glossitis, stomatitis, edema of the legs, soft systolic murmur.

• Amount of iron transferred to the foetus is unaffected at birth.
• During first year of life, poor growth, susceptible to infectious diseases.
• Increased incidence of low birth wt.,IUD.
• Hyperplacentosis due to anoxia.

Investigations

• Hbgm%- reduction is a relatively late development.
• measurement of Hb is the simplest practical test at our hand on the basis of which further action is taken.
• Perpheral smear- microcytic hypochromic. anisocytosis and poikilocytosis reticulocytosis.
• Serum iron – normal 13-27 micromol/l. this shows marked diurnal variation – not good indicator.
• Total iron binding capacity normal 45-72 micromol/l level. Increases in iron deficiency anemia and decreases in chronic infection.
• Serum iron
  • Not a reliable indicator of iron stores .
  • Fluctuates widely.
  • Affected by recent ingestion of iron and other factors such as infection.
• Serum feritine
  • high molecular weight glycoprotein .
  • normal range is of 15-300 pg/l.
  • reflects iron store accurately and quantitatively.
  • assessed by a sensitive immuno raidometric assey.
  • first test to become abnormal in iron deficiency anemia
• Stool examination to rule out occult blood and parasites
• Urine examination to rule out UTI.

Treatment

• Treatment depends upon degree of anemia available facilities and compliance of the patient
• Mild to moderate degree of anemia can be treated on out patient basis with oral iron therapy and counseling for diet.
• Severe degree of anemia needs hospitalization

A. oral therapy

• Iron is best absorbed in ferrous form. Preparations available are:

• Oral therapy given twice to thrice daily with food.
• Should be continued till blood picture becomes normal.
• The haemoglobin concentration is expected to rise at the rate of about 0.7-1 gm% per week
• Side effects : –
  • Intolerance
  • Nausea
  • epigastric pain
  • constipation

B. Parenteral therapy

• Intravenous route

1. repeated injections
2. total dose infusion

• Intramuscular route
• Indications of parenteral therapy
  • Intolerance to oral therapy.
  • Poor patient compliance.
  • Anemia diagnosed at 30-36 weeks of pregnancy
• The expected rise in haemoglobin concentration after parenteral therapy is 0.7-1 gm/100ml per week
• TDI (total dose infusion) Formula

1. 3 × Wt (100-Hb%) mg of elemental iron. Wt=patients weight in pounds Hb%= observed Hb in percentage. Additional 50% added for partial replenishment of the body store iron.
2. Elemental iron needed (mg) = (Normal Hb – Patient’s Hb) x Weight (kg) x 2.21 + 1000
3. 250 mg elemental iron for each g of Hb below normal.

• Side effects of parenteral iron therapy:
  • Painful
  • injection site abscess formation
  • discoloration of skin
  • Pyrexia
  • lymph adenopathy
  • head ache
  • Nausea
  • vomiting
  • allergic reactions
• Role of blood transfusion – very much limited.
• Indications are :
  • Patient with severe anemia seen after 36 weeks of pregnancy
  • Refractory anemia
  • Anemia due to blood loss

Prevention:

• To educate school going girls about iron deficiency anemia
• Counseling for diet in early pregnancy
• Deworming in second trimester of pregnancy
• To encourage the women who have not attained the age of child bearing to have adequate body iron store
• Fortification of food like salt with iron at national level.