Tests Performed During Pregnancy
First Trimester

Experts agree that a woman should begin to undergo routine screening tests either before conception or at her first prenatal visit. These tests alert doctors to potential problems and provide a basis for comparison as the pregnancy progresses. Here are some straightforward answers to questions about the most common tests during pregnancy, their risks and why they are necessary.

The Tests:

• Tests for glucose, protein and blood in the urine to detect problems such as impaired kidney function and diabetes

• A cervical culture for gonorrhea and chlamydia

• Blood tests to determine blood type and Rh type (to test for Rh incompatibility) and to check for anemia

• Tests for rubella and toxoplasmosis (a parasitic infection) and hepatitis B

• Chorionic Villus Sampling (CVS) detect defects in the fetus as early as the ninth week of pregnancy. The problem: The possible risk the test poses. Studies conducted in 1992 yielded conflicting results concerning the safety of CVS. Researchers at Michael Reese-Humana Hospital in Chicago found a higher incidence of limb defects in babies born to women who had undergone CVS. However, most other studies, including a later one conducted by researchers at Jefferson Medical College in Philadelphia, found CVS to be safe. Before having CVS, discuss the benefits and risks of the procedure with your doctor, and don't be afraid to request a second opinion.

• Blood tests–to determine your blood type, whether you are Rh negative or positive, and whether you have antibodies in your blood that might increase the likelihood of your baby being anemic or jaundiced as a newborn.

The Importance of Rh Factor
You may have lived your entire life without knowing whether your blood has the so-called Rh factor and not think anything of it. However, during pregnancy it’s important information. Your genes determine whether or not your red blood cells have this type of protein. Rh factor has no importance to your health before you become pregnant.

When you are pregnant, if you do not have the Rh factor (that is if you are "Rh negative") and if your baby’s does (if he’s "Rh positive"), problems can arise. Your immune system may recognize your baby’s blood as a foreign substance and produce antibodies that can result in fetal damage or death. This occurs most often during the second and later pregnancies of Rh-negative moms. Your first child will usually not be affected by it. By testing your blood, your doctor can discover if your blood is making antibodies. If this is the case your doctor can give you an injection to prevent antibodies from forming and prevent fetal damage or death.

• Pap smear–to test for the risk of developing cervical cancer.

• Urinalysis–to ensure that you don’t have a bladder or kidney infection or diabetes.