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The first test of your pregnancy may have involved peeing on a stick, but that's only the beginning of the tests you'll take during the next nine months. In fact, most of the major prenatal testing starts during your first prenatal visit. Whether you're seeing your regular doctor or a new OB or nurse-midwife, you can expect the same standard of care and the same prenatal lab tests. Just so you're prepared and know what's normal, here's a preview of standard first trimester testing.
First Trimester Testing
Urine Analysis and Culture
Collection of a clean catch of urine is always taken for analysis and culture during the initial prenatal visit. This helps identify any bacteria, such as E. coli, that may increase your risk of kidney infection or that may predispose a mother to preterm birth. High levels of bacteria are usually treated with oral antibiotics.
Complete Blood Count (CBC)
The CBC test panel includes hemoglobin/hematocrit, analysis of red blood cells, white blood cell count and platelet count.
Hemoglobin or hematocrit testing measures the iron stores a mom-to-be has built up. Your iron level can be affected by nutrition and absorption disorders such as anemia or bleeding of any kind. In the first trimester of pregnancy, anemia is defined by the Centers for Disease Control as a hemoglobin concentration less than 11 g/dL (hematocrit 33%). True iron deficiency anemia, which occurs in up to 25 percent of pregnant women, is the most common medical complication of pregnancy.
This type of testing is more for mom than for baby. In fact, an anemic mom does not usually lead to an anemic baby, because the fetus extracts the hemoglobin it needs from the mother, regardless of her iron level. Health care providers still treat low maternal iron levels, though, because they want to ensure that the expectant mom's hemoglobin concentration is sufficient to compensate for the blood she'll likely loose during delivery.
Women of color or of certain ethnic groups may be at higher risk for hemoglobin chain abnormalities '- blood cell defects that make it difficult for red blood cells to carry oxygen. Black women are at risk for sickle cell disease, Southeast Asian women for alpha thalassemia and Italian, Greek and or Corsican descendants for beta thalassemia. The CBC with red cell indices screens for these blood defects. Black women may also be screened with a hemoglobin electrophoresis. This test should also be considered for women of Greek, Corsican or Italian descent or Hispanic women of Caribbean origin.
Platelet count is another component of the CBC. Platelets allow blood to clot, and should be at a level that isn't too high or too low. During pregnancy, this level falls slightly but should never dip below 100,000. At your initial visit, your platelet count is taken as a baseline that will be used as a reference point to help your doctor identify later complications, such as preeclampsia, which negatively affect blood clotting.
If there's any reason to suspect an infection, white blood cell count and differential will also be part of the CBC. At the very beginning of pregnancy, it's normal for your white count to be slightly elevated, but this initial count still provides a baseline to which later tests will be compared. The differential separates out the types of white blood cells, which can help differentiate between viral and bacterial infections.