Prenatal Tests in the 1st Trimester

Your first prenatal appointments are full of new information and testing. It can be exciting and overwhelming. You want to be sure your baby is growing and developing normally and that you are doing all the right things for a healthy pregnancy.

Routine tests help keep close tabs on all of this -- that’s why keeping all your prenatal appointments is so important. Other screening tests can spot potential problems early.

Routine Tests

When you find out you’re pregnant, your doctor will want to quickly get an idea of your overall health.

History and physical exam. During your first or second prenatal visit, you’ll answer a lot of questions about your health and family histories. This information helps the doctor know whether you have any specific risks to address, such as an inherited genetic disorder. You will also have a physical exam. Your doctor will calculate your due date based on the date of your last menstrual period.

Pelvic exam and Pap smear. Prenatal testing during the first trimester begins with a pelvic exam and Pap smear to assess the health of your cervical cells. This testing screens for cervical cancer and for certain sexually transmitted diseases.

Blood tests. During this initial visit, you will also have a panel of blood tests. These tests help identify:

  • Illness or infections, such as hepatitis or syphilis (An HIV test is optional but recommended)
  • Risks for German measles and chickenpox, both of which can be very serious during pregnancy
  • Your blood type and Rh factor to see if your baby's and your blood are compatible
  • Your blood count, which can tell if you are anemic
  • Inherited diseases (Testing for inherited diseases - like cystic fibrosis - can also be done through testing saliva.)

Urine tests. At every prenatal visit, urine tests give a quick and easy snapshot of your health. They can reveal:

 

Optional Screening for Birth Defects

Late in your first trimester, your doctor may offer you screening for birth defects. Know that your doctor may instead offer you this screening in the second trimester. Or he or she may offer it in both trimesters.

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This optional screening involves a blood test and a nuchal translucency ultrasound or “first trimester screen.” If results from these tests show an increased risk for birth defects, you may need other tests as well.

Blood test. The blood test measures two proteins in your blood, which can be signs of certain birth defects such as Down syndrome.

Nuchal translucency ultrasound. This involves measurement of the back of the baby’s neck (called the nuchal fold). If this fold of skin is thicker than normal, it may be a sign of a birth defect. You may have a more detailed ultrasound if results from the nuchal ultrasound indicate a possible problem.

Chorionic villus sampling (CVS). If you are over age 35 or if screening shows an increased risk for birth defects, your doctor may recommend this test. It requires removing a sample of cells from the placenta. You can have this test between weeks 10 and 12. (Doctors can perform a similar test, amniocentesis, in the second trimester. You and your doctor will decide which option is better for you.)

Now what? If you find you are at risk for having a baby with a birth defect, or if test results indicate one is present, you may want to consult a genetic counselor. This person can help you understand the test results and risks, and can help you understand your options.

WebMD Medical Reference Reviewed by Trina Pagano, MD on January 16, 2019

Sources

SOURCES:

Lucile Packard Children’s Hospital at Stanford: "Common Tests During Pregnancy."

U.S. Department of Health and Human Services Office on Women’s Health: "Prenatal care and tests."

March of Dimes: "Routine prenatal tests" and "Carrier screening for cystic fibrosis."

American College of Nurse Midwives. "First Trimester Tests."

American College of Obstetricians and Gynecologists. "Screening for Birth Defects" and Your  Pregnancy and Childbirth, Month to Month, 5th edition, 2010. 

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