Anemia During Pregnancy

What causes anemia in pregnancy and who's at risk?

Anemia during pregnancy is caused by a decline in the concentration of hemoglobin in the blood. Hemoglobin plays a crucial role in the transport of oxygen to body tissues.

The reason hemoglobin concentrations tend to decrease during pregnancy is due to an increase in blood volume.

The demands of your growing fetus during pregnancy create a need for increased stores of iron in your own body.

Iron is a mineral that plays an important role in the production of red blood cells. Before you were pregnant, you needed about 15 milligrams (mg) of iron a day. Now you need twice this amount, or 30 mg.

If you're like most women, you won't have enough iron stores to provide this amount of iron each day throughout your pregnancy.

And it's difficult to get this much from your diet, even if you overeat, which is not good for you or your baby. Because up to 20 percent of all pregnant women are iron-deficient, iron supplements are often prescribed during the second half of pregnancy.

The volume of blood in your body expands dramatically during pregnancy — by about 45 percent. Most of this increase is due to an increase in blood plasma, the fluid portion of blood (as distinct from the part made up of red and white blood cells).

During the first half of pregnancy, the volume of plasma increases more rapidly than the volume of red blood cells. As a result, the concentration of red blood cells decreases during this time, until they have a chance to catch up with the increase in blood plasma.

Anemia during pregnancy can develop when there's not enough iron to fuel the increased production of red blood cells. The result is a decrease in hemoglobin concentrations in the blood.

Besides iron deficiency, other causes of anemia may include excessive blood loss (hemorrhage) from injury or surgery, chronic illness (such as serious infections or kidney disease) or a deficiency in folic acid (a vitamin needed for the production of red blood cells). In pregnant women, though, iron deficiency is the most common cause of anemia.

In the United States, many women of childbearing age don't get enough iron, even when they're not pregnant. Women lose iron along with the blood and tissue shed during their periods, which is one reason why they are more prone to anemia. Inadequate diet is another common reason.

During pregnancy, the increased need for iron to fuel the fetus's growth compounds the problems many women already have in getting enough iron.

Women who receive prenatal care and take iron supplements during pregnancy generally avoid the problems associated with iron-deficiency anemia. Among women who don't receive prenatal care, especially women who have little or no access to health care, iron-deficiency anemia is much more common.

Anemia in a pregnant woman can cause excessive fatigue and stress and make her more susceptible to illness, but it is unlikely to harm the fetus. Even when a woman is iron-deficient, the required amount of iron continues to be provided to the placenta and fetus.

What are the symptoms of anemia during pregnancy?

If your pregnancy anemia is mild, you may not notice symptoms. In moderate to severe anemia, you may experience some of the following:

* Excessive fatigue and weakness
* Pale complexion
* Shortness of breath
* Heart palpitations
* Dizziness, light-headedness, or fainting spells

How is pregnancy anemia diagnosed?

Your blood will be checked early in pregnancy, probably at the first visit to your doctor, to make sure that your hemoglobin levels are normal.

But even if you're not anemic at that point, your pregnancy may cause you to become at least mildly anemic later on, as your blood volume expands and more and more nutrients need to be delivered to the growing fetus.

In fact, iron-deficiency pregnancy anemia develops most often after 20 weeks of pregnancy. Many doctors prescribe an iron supplement to all their pregnant patients as a safeguard against the development of anemia.

What's the treatment for pregnancy anemia?

Treatment for anemia during pregnancy consists of taking in enough iron, prescribed in capsule or tablet form, and making sure you are getting enough foods high in iron, to increase your hemoglobin concentrations to normal levels.

Most likely you will already be taking extra iron by the second trimester, but if anemia develops despite this treatment, your dosage may need to be increased.

Taking iron supplements may sometimes make nausea and vomiting worse. You may want to take your iron supplements near bedtime if they tend to give you an upset stomach. You may find it helpful to keep them near your toothbrush as a reminder to take them every day. Like any medication, keep iron capsules or tablets away from children.

Very rarely, blood transfusions may be required in a pregnant woman who is severely anemic and has had significant blood loss. Transfusions may also be needed in a severely anemic woman who needs surgery.