Prenatal Screening & Diagnostic Testing Decision Tool

A project by the Genetic Support Foundation

There are many prenatal genetic screening and testing options available that can provide information about the possibility of certain birth defects and genetic conditions in a baby. It can be difficult to know whether or not to undergo any of these options during a pregnancy, and if so, which one to choose.

At the Genetic Support Foundation, we believe that these decisions are a personal choice, and they depend on your values, beliefs, and family planning goals. This tool will walk you through some important things to think about as you are considering the various screening and diagnostic testing options available to you during pregnancy. Upon completing the questions, you will be provided with a summary sheet that may offer a helpful starting point for talking through next steps with your healthcare provider.

While this decision tool was created with currently expecting parents in mind, this tool may also be useful to you if you are considering becoming pregnant in the future.

Click the "NEXT" button to begin...

Most babies are born healthy. However, with every pregnancy, there is a background chance of at least 3% to have a baby with some type of underlying health condition or birth defect. A birth defect is described as a medical condition or physical change that is present in a baby at the time they are born. Some familiar examples of a birth defect include an opening in the baby’s spine (spina bifida) or a heart defect. Conditions that may affect the health of the baby include genetic conditions, such as trisomy 21 (Down syndrome).

There are many reasons why birth defects happen, but most of the time, the cause remains unknown. Over time, we have learned that the chance to have a baby with a specific birth defect is dependent on many factors, including but not limited to:

Age of the biological parents
Family history
Maternal medical conditions (e.g., diabetes)
Exposures during the pregnancy (e.g., medication)

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Most of the prenatal screens and diagnostic tests available to you during a pregnancy are designed to either assess the chance for a chromosome condition in the pregnancy or confirm a chromosome condition in the pregnancy.

Chromosomes are the structures within our cells that store our genetic information also known as our DNA. You might recall that individuals typically have 46 chromosomes in each of their cells and that these chromosomes come in pairs: one copy of each chromosome is inherited from the egg cell (or the mother) and the other copy is inherited from the sperm cell (or the father) at time of conception.

In some instances, an extra or missing chromosome will be passed on through the egg or the sperm. This can happen as a random (or sporadic) event due to the chromosomes not separating in the typical manner during the development of the egg or sperm cell.

Extra or missing genetic information can lead to certain developmental and/or health concerns in a baby, largely dependent on the chromosome that is extra (“trisomy”) or missing (“monosomy”). Most pregnancies with extra or missing amounts of genetic information tend to result in a miscarriage, oftentimes before a woman might even know she is pregnant. However, there are some chromosome conditions that can be present in babies at the time of birth.

Depending on the screen or diagnostic test elected, the chromosome conditions evaluated in a pregnancy can include:

We know that babies with sporadic chromosome conditions can be born to parents of any age. However, the main factor that influences the chance for a chromosome condition in any given pregnancy is the age of the mother (or egg) at time of delivery. As maternal age increases, the chance for a new chromosome condition in a pregnancy (such as Down syndrome, trisomy 18, trisomy 13, and certain sex chromosome variations) also gradually increases. Use the calculator below to see how this chance is revised depending on age of the mother (or yourself, if applicable) at the time of delivery.

In order to understand your prenatal screening and testing options, it is important to make sure we clarify the differences between a screening test and a diagnostic test.

Click NEXT to learn more.

In order to understand your prenatal screening and testing options, it is important to make sure we clarify the differences between a screening test and a diagnostic test.

Screening tests:These options include prenatal ultrasounds (e.g., nuchal translucency, second-trimester anatomy ultrasound) as well as maternal blood draws (e.g., maternal serum screening, cell-free DNA screening). Results from a screen can tell you if there is a higher or lower chance for certain chromosome conditions (and sometimes other birth defects).

Click NEXT to learn more.

In order to understand your prenatal screening and testing options, it is important to make sure we clarify the differences between a screening test and a diagnostic test.

Screening tests: These options include prenatal ultrasounds (e.g., nuchal translucency, second-trimester anatomy ultrasound) as well as maternal blood draws (e.g., maternal serum screening, cell-free DNA screening). Results from a screen can tell you if there is a higher or lower chance for certain chromosome conditions (and sometimes other birth defects).

Diagnostic tests: These options can provide more definitive information rather than just a probability or chance of a chromosome condition/birth defect in the pregnancy. During a pregnancy, these options include the chorionic villus sampling (CVS) procedure or the amniocentesis procedure. Unlike screening options which do not cause any harm or risk to the pregnancy, diagnostic testing options are associated with a small risk of a pregnancy complication following the procedure, including miscarriage.

The following are the main prenatal screening tests available during a pregnancy and the general timeframe in which they are offered (click on the videos to learn more):

The following are the main diagnostic tests available during a pregnancy and the general timeframe in which they are offered (click on the videos to learn more):

After learning more about the specifics when it comes to your screening and diagnostic testing options, you might have a gut reaction for how you would proceed. You might also still be undecided. There is no one right path for everyone. General questions to ask yourself as you decide on whether to pursue any of these options include 1) what type of information are you are seeking? 2) how will that information be useful to you in your family planning?

There are generally four paths that people will consider moving forward. Click on the path below to learn more about each one or click “NEXT” to proceed to the survey.

Some people feel that prenatal screening and diagnostic testing is not right for them.

They may prefer not to face the decision of whether or not to have a diagnostic test if a screening test came back with a result showing a higher chance of having a genetic condition.
They may feel confident that, even if the developing baby did have a genetic condition, they would not do anything differently in their pregnancy.

Some people feel that it would be best for them to start with a screening test, which does not present any risk to the pregnancy (such as miscarriage), and then decide whether or not to undergo any further diagnostic testing based on the results of the screening test. If the screen indicates that the chance of a genetic condition or birth defect is low, many people decide that it is not worth the risk to undergo a diagnostic test such as amniocentesis. On the other hand, if the chance of a genetic condition is increased based on a screening test, they may wish to consider further diagnostic testing such as the amniocentesis in order to confirm the screening test results.

Some people feel that they need to know as much as they can about the health of the developing baby and are willing to accept the risk associated with diagnostic testing to get that information. These tests can tell you about many possible genetic conditions in the pregnancy with a high degree of certainty. However, no test checks for every genetic or health condition, and no test can guarantee the birth of a healthy baby.

Some people feel that they would not consider any screening or diagnostic testing unless a difference was revealed by ultrasound. If the ultrasound unexpectedly showed a soft marker or structural difference, only then would they revisit their screening and diagnostic testing options with their healthcare provider. Here are some things to keep in mind: Babies with normal ultrasounds can have genetic conditions (and babies with markers or structural differences can be otherwise healthy). Ultrasound is not a perfect test, but in some cases, it can indicate if there is a higher chance for an underlying health concern, such as a birth defect.

This survey is designed to walk you through some questions to help identify what is most important to you in considering prenatal testing options. Upon completing the questions, you will be provided with a summary sheet that may offer a helpful starting point for talking through next steps with your healthcare provider.

How concerned are you about the possibility of a genetic condition in the baby?

I am extremely anxious about the possibility of a genetic condition in my baby.
I am a little concerned about the possibility of a genetic condition with the baby.
I am not worried. I feel that everything is likely fine.

Are you willing to accept some risk of miscarriage (typically less than 1% chance) to learn with as much accuracy as possible if the baby has a diagnosable genetic condition?

Yes - I would want to know if my pregnancy is affected with a diagnosable genetic condition and I would accept a small risk to learn this.
It depends - I would only elect a test that is associated with risk of miscarriage if I knew that the chance of a genetic condition in my pregnancy was increased.
No - it would be very unlikely for me to consider any test that could cause me to miscarry my pregnancy under any circumstance.

Would you consider ending a pregnancy if a genetic condition was diagnosed during the pregnancy?

Yes - information would be important because I would likely consider ending the pregnancy if a genetic condition was diagnosed.
No - I would not consider ending the pregnancy regardless of results of a genetic test.
Not sure - not having faced this decision, it is hard to know what I would do. Depends on what the condition is (for example, severity, how it affects life expectancy, etc.).

A screening result may indicate an increased chance for a genetic condition. In many cases, when screening results return saying there is a higher chance of a condition, the baby does not actually have the condition. How do you feel about the possibility of uncertainty?

Very uncomfortable - I don’t like probabilities or results that indicate, for example, a 20% chance of my baby having a condition. Tell me only what you know for sure.
It depends on the situation - I just would like to be prepared for the possibility of uncertain results ahead of time.
I am quite comfortable with uncertainty - I understand this means I do not have “yes” or “no” answers, but that’s OK with me.

I would consider a diagnostic test, such as a CVS or amniocentesis, if a screen told me that the chance of a genetic condition in the pregnancy was increased.

Yes - I would want to know for sure if the baby was affected with a genetic condition if there was an increased likelihood of the condition based on a screen.
No - I do not think I would undergo a diagnostic test that could cause me a risk of miscarriage, even if the risk of miscarriage was small; I would be OK waiting until the baby was born to know for sure about whether or not the genetic condition was present.
Depends on how high the chance of a condition is, the specific condition, and the level of risk that comes with diagnostic testing.

Would a result from a screening test that indicated a low chance of a genetic condition in the baby be reassuring to me even though I know this does not mean that there is zero chance?

Yes - I think I would find some peace of mind with a normal screening result, but know that there is still a residual chance of the genetic condition in my pregnancy.
No - I really feel I need to know for sure; I would rather have a test that can give me “yes” or “no” answers.
No - I already feel that the chance is low, so I don’t feel like I need any testing to give me more reassurance.

Knowing about a genetic condition before the baby arrives would help me feel prepared.

Agree - I am a planner and I would want to know ahead of time to be able to learn more about the condition, connect with others who have children with the same condition, prepare mentally, etc.
Disagree - Whatever will be will be and I will take it as it comes; I don’t think that knowing before the baby arrives would necessarily be of benefit to me personally.
Depends - One reason I may want to know is if there is something we would do differently to improve the outcome for the baby.

Your Answers:

We are hopeful that this decision tool has provided you with helpful information and that you feel more equipped to take part in the conversation as you navigate your prenatal screening and diagnostic testing options with your healthcare provider. We wish you well in your family planning!

For additional resources, please visit our patient library at www.geneticsupport.org

You can also click here if you would to schedule a visit with one of our certified genetic counselors to further review the options introduced in our decision tool as well as to review your baseline reproductive risks