Prenatal Blood Testing - Which Tests Are Performed

Prenatal Testing

The purpose of these tests is to diagnose existing problems that may affect the mother’s or baby’s health, identify and address problems as they arise, and to assess the risk of a baby having a chromosomal or genetic abnormality.

Most of the routine tests are associated with infections or conditions that should be resolved prior to a woman getting pregnant or, if she is already pregnant, should be resolved and/or monitored during her pregnancy.

The following pages contain information on many of these routine and some of the less routine tests. There may be, however, other tests that your doctor will recommend based on your personal medical history.

Pre-Conception (Pre-Pregnancy)
When a couple is considering having a child, they should consult with their doctor(s). Based on their family and medical histories, the health care professional(s) may recommend some or all of the following key routine laboratory tests:
Immunity to Rubella (German Measles)
HIV
Gonorrhea, chlamydia, and syphilis
Blood Type and Antibody screen
Hepatitis B screening
Hemoglobin
CBC (complete Blood count)

Rubella is caused by a virus that is passed from person-to-person by coughs or sneezes. Any contact with the nasal or throat secretions of an infected person can spread the virus. Women who have either had a Rubella infection or have received the vaccination will have an antibody in their blood that will usually prevent them from getting the infection a second time. This antibody also protects the unborn baby against the virus; this protection is called immunity.

HIV is the virus that causes AIDS (Acquired Immunodeficiency Syndrome). At least 90-95% of individuals who are infected with the HIV virus will, within three months of exposure, develop enough antibodies to have a positive HIV test; over 99% of HIV infected individuals will have a positive test within six months. A new HIV test, called the HIV Proviral DNA test, has been shown to be 99% accurate at detecting HIV at 28 days after infection. If a pregnant woman is infected with the HIV virus, it can be passed to and infect her baby.

Gonorrhea, Chlamydia, and Syphilis are three common sexually transmitted diseases (STDs). These diseases are caused by bacterial infections and can lead to a miscarriage or can infect the baby prior to or during delivery.

Blood types are either A, B, AB, or O, and Rh positive or negative. Both the mother and baby may experience problems if their blood types are different, or if the mother has antibodies (antiglobulins) that will react with antigens (proteins or factors) on the baby’s red blood cells.

The Hepatitis B screening test is called a Hepatitis B Surface Antigen. It detects a protein produced by the virus and can detect a Hepatitis B infection even before it is causing symptoms. If a woman who is considering getting pregnant tests positive for Hepatitis B, she should talk to her doctor about how long she should wait for the infection to resolve before becoming pregnant.

Hemoglobin is the protein in red blood cells (RBCs) that gives blood its red color. It binds to oxygen in your lungs, transports it throughout the body, and releases it to the cells and tissues. During pregnancy, a woman’s hemoglobin must transport enough oxygen to meet both her and her baby’s needs. If a woman has insufficient hemoglobin, she is said to be anemic. Many pregnant women will experience some degree of anemia. Anemia can be caused by decreased RBC production, increased RBC destruction, or by increased RBC (blood) loss.

Other less routine testing:
Varicella zoster viral testing for immunity to chicken pox
TORCH panel if herpes, CMV, or toxoplasmosis is suspected
Bacterial vaginosis

Testing that may be offered to both the woman and her partner to evaluate the risk of inherited diseases:
Genetic testing for inherited diseases
Genetic hemoglobin disorders

The American College of Obstetricians and Gynecologists has stated, “All pregnant women should do prenatal screening”.

For more information on these tests, visit www.LabSafe.com