Iron metabolosm and anemia in pregnancy

Total iron content in the body is 38mg/kg and 70% of them are found in the hemoglobin and 30% in tissues.Iron loss from the body is not under regulation. Usual losses are in the form of menstrual loss and epithelial desquamation from the gut and skin. These losses amount to about 2mg/day. The iron balance is maintained by the iron absorption. Iron absorption is regulated by the amount of iron stores and the rate of erythropoiesis.

Iron absorption takes place at duodenum. Organic heme iron is well absorbed where as inorganic non-heme iron is poorly absorbed. Phytates, phosphates and tannin inhibit iron absorption. This factor has to be born in mind when dietary advice is given to the patient.

In pregnancy placental lactogen stimulates the erythropoietin secretion and produces bone marrow hyperplasia. This results in linear gradual increase in red cell mass, which reaches the peak of about 25% increase by 32-34 weeks of POA. This increase in red cell mass is enhanced by iron and folate supplementation.

Plasma volume too increases by about 40% and the net result is dilution of blood and dilutional (relative/physiological) anemia despite of increase in red cell mass. This factor has to be in mind when interpreting the Hb levels (normal is about 10-11g/dl) and hematocrit levels (normal is about 35%) in pregnancy.

Iron loss via menstrual blood (about 360mg) is saved during pregnancy. But the fetus totally depends on maternal circulation for its iron need (about 500mg). Also the need of iron is increased during pregnancy due to the increased red cell production (by about 500mg) and storage for future lactation (by about 180mg). Additional loss (of about 180mg) will occur at the time of partus. Hence, maternal intake has to be adequate to meet the net iron loss of 1000mg during pregnancy. Therefore in pregnancy iron requirement increase by about 3.6mg/day. Iron absorption is increased in pregnancy and iron supplementation in pregnancy will show good response.

Anemia in pregnancy

Anemia is a common medical disorder in pregnancy. The situation is worse in developing countries due to the poor nutritional status. Though anemia is associated with maternal mortality and morbidity, effective management can prevent most of them.

Inadequate erythropoiesis due to iron, folate and vitamin B12 deficiency and chronic blood loss are the commonest causes for anemia in pregnancy. Leukemia, sickle cell disease, thalassemia, myelodysplasias and hemolytic anemia are rare conditions but need to be born in mind while assessing the patients.

Effects of anemia in pregnancy

•     Increased risk of abortion
•     Increased risk of premature labour
•     Increased risk of intra uterine growth restriction (IUGR)
•     Lethargy
•     Ill health
•     Dyspepsia
•     Heart failure
•     Worsening of heart diseases
•     Bad prognosis following post partum hemorrhage (PPH)  and maternal death
•     Increased risk of puerperal sepsis