Anemia is perhaps the most common complication in pregnancy seen in developing countries. The severe forms of anemia are as common as toxemia and they contribute to a major percentage of maternal deaths. Incidence of anemia varies from 40-90% in India. Anemia contributes to 10-15% of direct maternal deaths in India.
DEFINITION
Anemia is defined as low hemoglobin concentration resulting in a decrease in oxygen carrying capacity of blood. According to WHO, a Hb level of 11 g% is considered as anemia during pregnancy. In India, Hb level less than 10 g% is considered as anemia as defined by Federation of Obstetrics and Gynecological Societies of India.
Hematological Changes during Pregnancy
Plasma volume: During pregnancy, the plasma volume increases by 40-45%. This increase begins at the 6th week and the maximum increase occurs before the 32nd week.
Red cell mass: The red cell mass increases by 15-20%. The red cell mass rises more rapidly after the first trimester of pregnancy.
The disproportionate increase between plasma volume and red cell mass results in physiological anemia of pregnancy. In this condition, the Hb level is 10 g%. RBC count is 3.2 million/mm³, PCV is 30% and the peripheral smear shows normal morphology of RBC.
CAUSES OF ANEMIA IN PREGNANCY
The causes of anemia in pregnancy are nutritional (50%), parasitic infestation (25-30%), chronic blood loss (5-7%), hemoglobinopathies (1-2%) and other causes such as leukemia and hemolytic anemia
Nutritional Causes
The materials essential for erythropoiesis, the deficiencies of which are mainly responsible for anemia in pregnancy are iron, folic acid and vitamin B12. The deficiencies of these substances are common, though mixed deficiencies are also met with. As a result, it is common to find in pregnancy not only iron deficiency anemia but also anemia due to deficiency of folic acid or vitamin B-12 in addition.
Iron Deficiency Anemia
Iron deficiency anemia is very common in pregnancy. The iron deficiency may exist prior to pregnancy, in which case pregnancy makes it worse, or it may originate during pregnancy.
CAUSES
The various causes of iron deficiency anemia during pregnancy are:
Poor intake of dietary iron: The average Indian diet would appear adequate in iron content (20-22 mg) for a non-pregnant adult woman. The content in the diet of women in the lower socioeconomic group is very low. These women exist on a diet which gives them little opportunity to store iron.
Poor absorption/bioavailability: Only 3-5% of dietary iron is absorbed in normal, apparently healthy individuals. In pregnancy, it is felt that a minimum of 4-6 mg of iron should be absorbed daily to maintain an iron balance which can be had only from 40-60 mg of dietary iron.
Increased demand during pregnancy: In a typical gestation with a single fetus, the maternal need for iron induced by pregnancy changes may be around 1000 mg. The fetus and the placenta require around 300 mg and 500 mg for maternal Hb mass expansion. Approximately 200mg is shed through the gut, urine and the skin. In addition to this provision has to be made for the loss at delivery (150-200 mg) and lactation (150-200 mg). Unless the difference between the amount of stored iron available to the mother and the iron requirement of normal pregnancy is compensated, iron deficiency anemia develops.
Continuous loss of blood: Iron deficiency anemia may also arise from certain associated illnesses such as ankylostomiasis, bleeding piles, dysenteries etc.
CLINICAL FEATURES
In the mild forms, there may be few symptoms and the anemia is detected in routine antenatal screening. Severe forms give rise to symptoms. The following are some of the features noted in these women:
Parity: Iron deficiency anemia is more common in multigravidas or when the interval between pregnancies is less
Multiple pregnancy: In multiple pregnancy the demand for iron is more and hence there is increased likelihood of developing iron deficiency anemia.
History of chronic illnesses: Repeated urinary tract infection, worm infestation and history of menorrhagia prior to pregnancy may be elicited. Lethargy ,palpitation and breathlessness on exertion may be the complaints in severe forms of anemia.
Examination findings: These include pallol, presence of edema of feet and face. In very severe forms patient may have features of cardiac failure.
INVESTIGATIONS
The following investigations are done to confirm the diagnosis of iron deficiency anemia.
1) Hemoglobin estimation to determine the severity of anemia.
2) Peripheral blood smear in iron deficiency anemia is characterstic with microcytosis, anisocytosis, poikilocytosis and pale-staining (hypochromic) vacuolated red cells in abundance.
3) Mean cell volume is below 80 cubic microns and the MCHC is less than 30%. Levels of serum ferritin will be low and total iron binding capacity is raised indicating deficiency of iron.
4) Bone marrow is not done routinely to diagnose but when it is done to differentiate from other types of anemia, it will be normoblastic with depleted iron.
5) Stool examination done may reveal coexisting ankylostomiasis. of
MANAGEMENT
This is the most common type anemia encountered in pregnancy and hence certain preventive measures need to be considered apart from treatment when the diagnosis is made.
Preventive Measures:
1. Proper counselling to avoid frequent childbirth. At least 2-3 years gap is necessary between pregnancies.
2. Prophylactic iron therapy during pregnancy. In India it is recommended that at least 100 tablets of 100 mg of iron and 500 hg of folic acid must be given to all pregnant women in second and third trimester of pregnancy. Under the Child Survival Safe Motherhood (CSSM) programme, administration of mebendezole (for deworming) has also been recommended along with iron and folic acid.
TREATMENT
Treatment will depend on the degree of anemia and the period of gestation at diagnosis.
If the pregnant woman is severely anemic (Hb <6.5 g%) and the period of gestation is near term or if the patient is in labour, then she may require blood transfusion. However, if the anemia is not severe, iron therapy may be initiated.
ORAL TREATMENT: The trend is to give ferrous salts as they are found to be better absorbed and more effective: Ferrous sulphate, carbonate, fumarate and gluconates are all used in the dose of 200 mg three times a day. With oral iron therapy, there may be gastrointestinal side effects, which are decreased if iron tablets are taken with food.
Response to treatment is observed by increase in reticulocytes within a week of starting iron therapy and the Hb level begins to rise. If there is no response in spite of treatment, then further investigations are required to rule out other causes of anemia.
Parenteral therapy. This is usually indicated when the pregnant mother is unable to take oral therapy due to side effects or is non-compliant. This can be given either intramuscularly or intravenously.
Intramuscular therapy: Iron-dextran complex is reported to be the least toxic and to give good results when injected intramuscularly. The dosage administered depends upon the severity of the fanemia. Oral iron is stopped at least 24 hours priory to injection to minimise reaction. The injection has to be given in a zigzag manner (Z technique). Iron-sorbitol-citric acid complex is another preparation of iron for intramuscular therapy.
Intravenous therapy: A total dose of iron is given in the form of an intravenous infusion. The deficit is first calculated using the following formula:
2.4 x weight (Kg) x (15 - Hb of patient) + 1000g
The total deficit calculated in the form of iron dextran is diluted in 500 ml of 5% glucose as a slow intravenous infusion. During infusion, careful watch is kept for any untoward reactions. Occasionally, Rigors, chest pain and palpitation may be observed. When reactions are observed, the drip should be stopped immediately. Facilities for immediate resuscitation should be kept ready before starting the infusion. Administration of an anti-histaminic minimises the reaction.
FOLIC ACID AND VITAMIN B12
Apart from iron, the materials essential for erythropoiesis are folic acid and vitamin B₁₂. These are consumed in food in the conjugated form, and the active principles are liberated in the gastrointestinal tract and absorbed. The recommended daily allowance of folic acid during pregnancy is 300-400 m. The iron tablets distributed during pregnancy by the government contain folic acid as well.
Deficiencies of folic acid and vitamin B₁₂ give rise to macrocytic anemia with or without megaloblastic bone marrow. If in combination, iron deficiency is also present, then macrocytic hypochromic anemia results.
The characteristic hematological features of this anemia are a mean cell volume greater than 90 cubic microns. A stained peripheral smear shows macrocytes in abundance with anisocytosis and poikilocytosis. In severe cases, normoblasts and at times megaloblasts, are seen in the peripheral smear.
EFFECT OF ANEMIA ON PREGNANCY
1) In the antenatal period, an anemic pregnant mother is at a greater risk of having associated urinary or other infection.
2) There is increased risk of preterm labour.
3) At the time of delivery, an anemic mother cannot withstand even normal blood loss, and the woman may go into cardiac failure immediately after delivery depending on the severity of anemia.
4) During puerperium, there is an increased risk of infection, developing venous thrombosis and delayed wound healing if there is an operative delivery.
5) An anemic mother has an increased risk of having a low birth weight baby due to prematurity or intrauterine growth restriction.
MANAGEMENT OF ANEMIA
1) Preventing the development of any severe degree of anemia should be the primary aim. Spotting the anemia early by efficient antenatal care is the only effective way.
2) Once the anemia develops and its type is recognised, appropriate hematinics should be prescribed to obtain the optimum hemoglobin level before term/labour.
3) If the anemia is detected early and is not severe, iron and folate supplements may suffice. If the patient is not able to tolerate oral iron, then iron may have to be given parenterally.
4) If anemia persists in spite of adequate treatment, then detailed investigations should be done to exclude other forms of anemia such as hemoglobinopathies etc.
5) Blood transfusion: This is indicated when severe anemia is detected in late pregnancy. Blood transfusion in anemic patients is associated with a an increased risk of congestive cardiac failure and preferm labour. To avoid an overload to the circulation, it is better to transfuse packed cel slowly under cover of a diuretic.
6) Exchange transfusion. If the patient is severely anemic and is in cardiac failure, blood transfusion may worsen the situation. In this situation if packed cells could be administered in large quantities, sufficient to produce rapid improvement without increasing the blood volume and the load on the heart, it would be safer. For this purpose, exchange transfusion is exceedingly useful. About 1500 ml of blood is withdrawn from one vein, while through an opposite vein 1300 ml of compatible packed cell blood is given simultaneously. The results of this treatment have been most gratifying.
It is pointed out that exchange transfusion is not to be employed as a routine in all the cases. It is only a treatment of extreme urgency and utmost necessity Its main value is to obtain an immediate responsex to tide over a crisis.
MANAGEMENT IN LABOUR
In moderate and severe anemia, labour is an anxious and worrying problem. In the first stage of labour the patient is kept in bed, sedated and oxygen is kept ready in case of need. The second stage of labour is cut short by outlet forceps under pudendal block analgesics. An injection of lasix is given to prevent cardiac failure in severely anemic women or if the woman is already in failure. Proper oxytocics should be kept available in case of postpartum hemorrhage since these patients cannot afford to lose even the normal amount of blood loss. In puerperium, there is a risk of puerperal sepsis and thrombophlebitis occurs more commonly in these women. Hence they require a course of antibiotics
Anemia in pregnancy should be detected early and managed, and is preventable. Women with severe anemia in late pregnancy should be referred to a tertiary care centre.