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The purpose of screening is early diagnosis and treatment of an infection. Screening tests are given to people without current symptoms, but who may be at high risk for certain diseases or conditions.

Screening Tests

You will get several screening tests as part of your routine prenatal care. Screening tests can help your doctor know if you are at risk for certain infections during pregnancy. Tests may include:

  • Blood test—Your blood is checked for the presence of antibodies to chickenpox and rubella (German measles). Antibodies are proteins that your body has made to fight an infection.
  • Culture—The doctor will gently swab your anus, rectum, and/or vagina, and cervix to see if group B strep or a sexually transmitted disease is present. The culture will either be looked at under a microscope in the office or sent to a lab for testing.
  • Ultrasound —A technician will hold a device over the abdomen that bounces sound waves off the uterus and your developing baby. The sound waves make electrical impulses that create a picture of the baby on a video monitor. This helps the doctor check for any fetal abnormalities that might indicate an infection (usually viral) in the mother.
  • Urinalysis—This is a test to check for bacteria in the urine. After you urinate into a cup, your healthcare provider will use a specially treated paper strip to check for signs of a bacterial infection in the urine.
  • If you are at high risk you may be screened for toxoplasmosis, cytomegalovirus, parvovirus or zika virus.

Screening Guidelines

The Centers for Disease Control and Prevention (CDC) recommends that pregnant women are screened for sexually transmitted diseases (STDs) on their first prenatal visit. Screening will look for the following STDs:

In some cases, your doctor will also screen you for Hepatitis C and bacterial vaginosis.

The CDC also recommends that you are screened for Group B streptococcal disease (GBS) at 35-37 weeks. If the test is positive, you will be given antibiotics to treat this infection during labor.

Pre-pregnancy Checkup

A pre-pregnancy checkup can help you avoid infection in pregnancy and improve the chances of having a healthy baby. At a pre-pregnancy visit, your healthcare provider will ask about your medical history, past pregnancies, and lifestyle. You can ask questions and discuss concerns, such as whether work or hobbies expose you to potential hazards.

Blood tests measure immunity to certain infections. If you have immunity, you cannot get the infection again. If you do not have immunity, you may be able to get a vaccine to protect you from the infection. During a pre-pregnancy visit, you can be checked for:

  • Chickenpox—Women not immune can be vaccinated before pregnancy. Conception should be postponed for three months.
  • Hepatitis B—The Centers for Disease Control and Prevention recommends that all pregnant women be screened for hepatitis B. Untreated infants of infected mothers have about a 50% risk of getting the virus. Prompt immunization and treatment after birth usually can prevent infection in the baby. However, high-risk women, such as healthcare workers, should consider vaccination prior to pregnancy.
  • Rubella—If you are not immune, you can be vaccinated before pregnancy. Conception should be postponed for 3 months after the vaccination .
  • Toxoplasmosis—Some healthcare providers screen for immunity to this infection. Unless a woman knows she is immune, she should not eat undercooked or raw meat, or handle cat litter.
  • Cytomegalovirus (CMV)—Healthcare and childcare workers may want to be tested for CMV before pregnancy to see if they have had CMV in the past. Routine screening for low-risk women is not recommended. If you already have had CMV, you have little cause for concern during pregnancy.
  • Tuberculosis (TB)—If you are from a country that has high rates of TB, you should be screened for this disease.


Apgar BS, Greenberg G, Yen G. Prevention of group B streptococcal disease in the newborn. Am Fam Physician. 2005;71(5):903-910.

Bacterial vaginosis—CDC fact sheet. Centers for Disease Control and Prevention website. Available at: Updated February 2, 2016. Accessed May 17, 2016.

Chickenpox. EBSCO DynaMed Plus website. Available at: Updated September 8, 2015. Accessed October 6, 2016.

Cytomegalovirus (CMV) and congenital CMV infection. Centers for Disease Control and Prevention website. Available at: Updated July 28, 2010. Accessed May 17, 2016.

Group B Strep (GBS). Centers for Disease Control and Prevention website. Available at: Updated May 23, 2016. Accessed May 17, 2016.

Pregnancy and fifth disease. Centers for Disease Control and Prevention website. Available at: Updated November 2, 2015. Accessed May 17, 2016.

Routine prenatal care. EBSCO DynaMed Plus website. Available at: Updated June 22, 2016. Accessed October 6, 2016.

Schrag SJ, Arnold KE, Mohle-Boetani JC, et al. Prenatal screening for infectious diseases and opportunities for prevention. Obstet Gynecol. 2003;102(4):753-760.

STDs and pregnancy. Centers for Disease Control and Prevention website. Available at: Updated May 20, 2016. Accessed May 17, 2016.

Urinary tract infection during pregnancy. American Pregnancy Association website. Available at: Updated August 2015. Accessed May 17, 2016.

Last reviewed May 2016 by Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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