Gestational anemia often results from the added requirements of a developing fetus. Nutritional anemias are the most common forms to develop. About 90% of the cases of anemia in pregnancy are of the iron-deficiency type. The remaining 10% are because of acquired or hereditary anemias, including folic acid deficiency, sickle cell disease, and thalassemia.
Anemia is the most common medical disorder of pregnancy, producing a higher incidence of infections and cardiac problems. Because the oxygen-carrying capacity of the blood is decreased, the heart tries to compensate by increasing its output. This effort increases the workload of the heart and stresses ventricular function.
Therefore, anemia that occurs with such other complications as pre-eclampsia may result in congestive heart failure. This type of anemia is treated with therapeutic doses of the required nutrient during gestation and is just one reason why it is vital for a woman to receive prenatal care.
Anemic effects are the same in the pregnant woman as in anyone else except that the anemia may develop more rapidly in pregnant women, making her vulnerable for the added effects of blood loss during delivery. Blood loss during delivery, even if minimal, is not well tolerated; and she is at risk for requiring blood transfusions.
Other anemias commonly found in pregnancy are:
Iron-deficiency anemia: Without additional iron, all pregnant women will conclude pregnancy with an iron deficit, even those who enjoy the most excellent nutrition. In most cases, an oral supplement will be enough; but, in all cases, adding vitamin C will dramatically increases the absorption of iron whether received from a supplement or from the diet. However, diet alone cannot replace gestational loss, and a supplement is almost always recommended. Foods that decrease iron absorption include bran, tea, coffee, milk, oxalates (in spinach and other greens) and egg yolk.
Sickle cell anemia is a recessive, hereditary, familial hemolytic anemia where abnormal hemoglobin types (SS or SC) produce recurrent attacks (crisis) of pain and fever. The anemia that occurs in normal pregnancies may trigger sickle cell disease and bring on more crisis. Pregnant women with sickle cell disease are prone to pyelonephritis (kidney inflammation), leg ulcers, bone infarction, cardiopathy, congestive heart failure, and preeclampsia. Urinary tract infections and hematuria (blood in the urine) are common. An aplastic crisis may follow serious infection. Often, blood transfusions are required to keep the hematocrit level at least 30%.
Thalassemia is another hereditary condition which can be aggravated by pregnancy. It results when an insufficient amount of hemoglobin is produced to fill the red blood cells (RBCs). The unbalanced synthesis of hemoglobin leads to premature RBC death and results in severe anemia. Thalassemia major may complicate pregnancy, and pre-eclampsia is more common in women with this disorder. It is also associated with low-birth-weight infants and increased fetal wastage. Placental weight often is increased, perhaps secondary to maternal anemia. The frequency of fetal distress from hypoxia is greater. Regular transfusions may be necessary and a folic acid supplement is highly recommended. Women with thalassemia major may die of chronic infection or progressive hepatic or cardiac failure – the result of excessive iron deposits in which much of the hemoglobin that is present is precipitated in the form of hard crystals. Thalassemia minor must be distinguished from iron deficiency anemia. Pregnancy will neither worsen thalassemia minor nor will it be compromised by the disease and, the anemia will not respond to iron therapy. In fact, prolonged parenteral iron can lead to harmful, excessive iron storage.
Hydatidiform mole, or molar pregnancy, is a condition in which an abnormal pregancy results in cells forming a mass of cysts resembling a bunch of grapes. In the beginning, the signs and symptoms cannot be distinguished from those of a normal pregnancy; but, later, vaginal bleeding occurs in almost every case. Early in the pregnancy, the uterus of about half the affected women is significantly larger than expected from the menstrual dates. Anemia from blood loss is just one of the problems resulting from this condition and results from intrauterine bleeding that happens when molar tissue separates from the uterine wall.
Hematocrit levels: An indirect index of the oxygen-carrying capacity is the packed red blood cell volume (hematocrit). The normal hematocrit range in pregnant women may be as low as 34% (normal for a non-pregnant woman is 37%-47%). This discrepancy has been explained by hydremia (dilution of the blood), or the physiologic anemia of pregnancy.
- In the first trimester, a pregnant woman at, or near, sea level, is anemic when her hemoglobin level is less than 11 g/dL or her hematocrit level falls below 37%.
- In the second trimester, she is anemic when the hemoglobin level is less than 10.5 g/dL or the hematocrit level falls below 35%.
- In the third trimester, she is anemic when the hemoglobin level is less than 10g/dL or the hematocrit level is less than 33%. In areas of high altitude, much higher values indicate anemia. For example, at 5000 feet, a hemoglobin level of less than 14 g/dL indicates anemia.
