One of the first tests you'll need when you become pregnant is a complete blood count or CBC. This measures a variety of factors in your blood, such as the number of white and red blood cells that you have. When you are pregnant, there are three important indicators your doctor will look for in your CBC test results: hemoglobin, hematacrit and your platelet count.
Hemoglobin is a protein in the blood that delivers oxygen to your cells, and hematacrit is a measure of red blood cells in the body. If either of these counts are low, it may indicate anemia, and your doctor would recommend a course of treatment to address the condition.
The platelets in your body are the substances that help your blood clot. It is critical that the platelet count be in the normal range because a woman looses a half liter of blood on average during pregnancy, and the platelets see to it that you don't lose any more than that [source: Family Education]. If your count is unusually low, your doctor will conduct further tests to source the problem and administer treatment as appropriate.