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Prenatal tests

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Your prenatal care will include several laboratory tests to help your doctor​​ evaluate your health and the well-being of your baby. 

Some of these tests are routinely performed on all pregnant women, and some of them are performed only if there are specific indications for the test. ​

Blood tests

Blood tests are usually performed on your first prenatal visit. These include:

  • A blood count, or hemoglobin, to check for anemia
  • A determination of your blood type and Rh factor
  • A test for abnormal antibodies in your blood that may indicate infection (syphilis, rubella or German measles, and hepatitis)

Pap smear and culture​​

Pap smear and culture: of the cervix and vagina are performed during the first prenatal exam, if indicated.


Urine is tested for infection during the first visit and will be checked at each subsequent visit for protein and sugar if ordered by your provider.

Diabetes Screening

Diabetes screening is usually performed between the 24th to the 28th week of pregnancy, but may be necessary earlier in your pregnancy.

Group B Streptococcus

A lab test to detect GBS bacteria is performed between 36 and 37 weeks of pregnancy. A positive culture requires treatment during labor. A mother with GBS can pass the bacteria on to her baby during delivery. As a result, some infants may become ill shortly after birth.

Babies who have GBS can develop pneumonia, sepsis (a blood infection), or meningitis. These infections are rare, but antibiotics given during labor further reduce the risk of infection.

AIDS/HIV testing

The American College of Obstetricians and Gynecologists and your provider strongly recommend that all pregnant women be tested for AIDS/HIV. Pregnant women known to be HIV positive can be treated with medication to minimize the risk of transmission to their baby.


Many women have ultrasounds performed during their pregnancies. Ultrasound uses sound waves to form a picture of your baby. There is no radiation (x-rays) involved in ultrasound and there is no known risk to the baby from the procedure. Your provider may request an ultrasound to help:

  • Decide how far along you are in the pregnancy
  • Determine how well the baby is growing
  • Look for certain birth defects (not all birth defects can be seen on ultrasound)
  • Determine the position of the baby

Ultrasounds are usually not performed in order to tell the sex of the baby. ​