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Prenatal Screenings

Authors:
  • Julie J. Martin, MS
Publication Type:

Lifestyle

Prenatal Screenings

Pregnancy can be an exciting time for parents. It can also be a time of worry over the baby's health. There are now many prenatal testing tools used to see if pregnant people and babies are at a higher risk for having a disease or condition.

Prenatal screening results may not give a “yes” or “no” about if there is a disease or if it will happen. It is also key to know that with any testing there could be:
  • False positive—The test is positive but the person does not have the issue or condition.
  • False negative—The test is negative but the person does have the issue or condition.

A test may also only be able to tell who is at high risk.

Birth Defects

Birth defects are health issues that may be caused by genes, genetic problems, or things in the world around us. They cause health issues that cannot always be treated or cured. Birth defects that are most often found by screenings are chromosome issues like Down syndrome and neural tube issues like spina bifida.

Screenings to Check the Pregnant Person's Health

A pregnant person’s health impacts their fetus' health. At the first prenatal care visit, the doctor will review their family and own health history. The doctor will offer routine tests so issues that could hurt the fetus can be checked and controlled.

Routine tests may include:

Some tests may be done to check:

Screenings to Check the Fetus' Health

Screenings also let the care team watch the fetus' health as it grows. If a screening has an odd result, more testing will be advised. Often 2 or more of these screenings will give the most reliable results. Some screenings are given to all pregnant people. Other tests are done because of a person's age or odd results of a routine screening.

Examples of screenings include:

Ultrasound

An ultrasound uses sound waves to make a picture of the baby on a screen. It can be used to figure out the fetal age. The test can also identify twins (or more), see how the fetus is growing, study breathing, and check the amount of amniotic fluid. An ultrasound may be done at anytime during the pregnancy. In the first 3 months it can be done to make sure the age of the fetus is known. It is often done again around 20 weeks of pregnancy to check how the fetus is growing.

Nuchal Translucency (NT)

This screening assesses a baby’s risk for Down or Turner syndrome in the first trimester. It uses ultrasound to measure the space in the tissue at the back of the fetus’ neck. Fluids can gather there if Down or Turner syndrome is present. The results of this test can show the need for more testing.

NT can also be used during this time to screen for heart problems in fetuses that do not have any chromosomal problems. More testing can be done later in the pregnancy with a fetal echocardiogram.

Triple Screen and Quad Screen

The triple screen looks for 3 things in the pregnant person's blood:

  • Alpha-fetoprotein, which is a protein the fetus makes
  • hCG (human chorionic gonadotropin), which is a hormone made in the placenta
  • Estriol, which is an estrogen made by the fetus and the placenta

Odd levels of these can mean possible Down syndrome or other chromosomal issues. It can also help find neural tube defects (spina bifida).

In addition to these three things, the quad screen also looks for Inhibin-A. This is a protein made by the placenta and ovaries. This test may be better able to identify Down syndrome. The false positive rate of the test is low.

Cell-Free Fetal DNA Testing

This is a blood test that can check the amount of the fetal DNA in the pregnant person's blood. This test can help see early in the pregnancy if a baby is at higher risk for some chromosomal issues like Down syndrome or Trisomy 18.

Non-stress Test (NST)/Biophysical Profile (BPP)

These tests are sometimes done with high-risk pregnancies to check:
  • The baby's heartbeat with fetal activity
  • How well the fetus is moving
  • How it is breathing
  • How much amniotic fluid is around the baby—too much or too little could cause problems
Non-stress tests are done late in the pregnancy if there is a high risk of problems or stillbirth.

Mental Aspects of Testing

These tests can be stressful for parents. If the results are not good the parents may have to make painful choices. The tests may help parents get ready to deal with the baby's health issue. But there may be no treatment that can be given before the fetus is born.

It is vital to know that some who test positive for a screening will test negative in follow-up tests.

Genetic counseling is key part of prenatal screenings. It can help parents see what the results mean, look at treatment choices, and think about the need for more testing.

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References

  • Category: prenatal testing. American Pregnancy Association website. Available at: http://www.americanpregnancy.org/catergory/prenatal-testing.
  • FAQ: Cell-free fetal DNA testing. UCSF Medical Center website. Available at: https://www.ucsfhealth.org/education/faq-cell-free-dna-screening.
  • Prenatal tests. March of Dimes website. Available at: https://www.marchofdimes.org/pregnancy/prenatal-tests.aspx.
  • Prenatal ultrasound screening. EBSCO DynaMed website. Available at: https://www.dynamed.com/evaluation/prenatal-ultrasound-screening.
  • Prenatal genetic screening tests. The American Congress of Obstetricians and Gynecologists website. Available at: https://www.acog.org/womens-health/faqs/prenatal-genetic-screening-tests.
  • Routine prenatal care. EBSCO DynaMed website. Available at: http://www.dynamed.com/management/routine-prenatal-care-36.
  • Special tests for monitoring fetal well-being. The American Congress of Obstetricians and Gynecologists website. Available at: http://www.acog.org/womens-health/faqs/special-tests-for-monitoring-fetal-well-being.
  • STDs during pregnancy. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/std/pregnancy/STDFact-Pregnancy.htm.
Last Updated:
2022-08-01

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This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.