Understanding Prenatal Screening and Genetic Testing

Prenatal testing can provide vital information about your baby's health. Learn the difference between screening and diagnostic tests, and understand your options in the first trimester.

first-trimester 11 min read
DNA strand representing genetic screening and inherited conditions during pregnancy

TL;DR

Prenatal screenings, such as NIPT and nuchal translucency scans, assess the risk of chromosomal conditions like Down syndrome. Unlike diagnostic tests (CVS or amniocentesis), screenings are non-invasive and provide a probability rather than a definitive diagnosis, helping you and your partner make informed decisions about your care.

Book Your First Visit
Important

Prenatal screening tests do not provide a definitive diagnosis. If a screening shows an increased risk, your doctor will discuss diagnostic options like CVS or amniocentesis to confirm the results.

In This Article

What Is the Difference Between Screening and Diagnostic Testing?

A screening test calculates the statistical probability that a baby may have a specific condition, whereas a diagnostic test provides a definitive 'yes' or 'no' answer by directly analyzing fetal cells.

Understanding this distinction is the first step in navigating prenatal care. Screenings are generally non-invasive—meaning they involve a simple blood draw or ultrasound—and carry no risk of miscarriage. They are designed to identify who might need further testing. If a screening comes back as 'high risk' or 'screen positive,' it does not mean your baby has a condition; it simply means the chance is higher than average. Diagnostic tests, on the other hand, are more involved. These procedures, such as chorionic villus sampling (CVS) or amniocentesis, involve collecting a small sample of tissue or fluid from around the baby. Because they look directly at the baby's DNA, they are 99.9% accurate. At Viva Eve, we guide you through these choices, ensuring you understand the clinical implications and the emotional weight of each path.

What Is NIPT (Cell-Free DNA) Screening?

Non-invasive prenatal testing (NIPT), also called cell-free DNA (cfDNA) screening, is a highly accurate blood test that screens for common chromosomal conditions like Down syndrome (Trisomy 21) as early as 10 weeks.

NIPT works by analyzing small fragments of DNA from the placenta that circulate in your bloodstream. It is incredibly effective at identifying Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). It can also identify the baby's biological sex and look for issues with the sex chromosomes. One of the biggest advantages of NIPT is that it can be done with a simple blood draw starting at 10 weeks of pregnancy. While it is not a diagnosis, it has a very low 'false positive' rate compared to older screening methods. For many couples, a 'low risk' NIPT result provides significant peace of mind early in the first trimester. We offer this screening to all our patients at our Midtown East and Forest Hills offices.

How Does the Nuchal Translucency (NT) Scan Work?

The nuchal translucency (NT) scan is a specialized ultrasound performed between weeks 11 and 13 that measures the clear space at the back of the baby's neck to screen for chromosomal issues and heart defects.

Babies with certain chromosomal conditions often have an increased amount of fluid in this specific neck area during the first trimester. By combining the NT measurement with a blood test (called a first-trimester screen), we can calculate a risk score for conditions like Down syndrome. Unlike NIPT, the NT scan is also a vital tool for checking the baby's physical development, including the heart and other major organs. At Viva Eve, our board-certified sonographers are experts in performing these delicate measurements. An increased NT measurement doesn't automatically mean there is a problem, but it does signal that we should look more closely. It is part of our comprehensive approach to monitoring your baby's health from every possible angle.

What Are the Diagnostic Testing Options: CVS and Amniocentesis?

Chorionic villus sampling (CVS) is performed between weeks 10 and 13, while amniocentesis is usually done after 15 weeks. Both provide a definitive genetic diagnosis but carry a very small risk of pregnancy loss.

If you choose to move forward with diagnostic testing, the timing often determines the procedure. CVS involves taking a tiny sample of the placenta, either through the cervix or through a needle in the abdomen. It can be done earlier than amniocentesis, which involves taking a sample of the amniotic fluid. Both procedures are guided by continuous ultrasound to ensure the baby is safe. The risk of miscarriage from these procedures is very low—typically cited as less than 0.5% (1 in 200 to 1 in 500) in experienced hands. For some families, the benefit of having a definitive answer outweighs this small risk. We discuss these options with deep compassion, recognizing that the decision to have a diagnostic test is deeply personal.
1. Women who will be 35 or older at the time of delivery. 2. Couples with a family history of genetic disorders. 3. Those who received an abnormal result on a screening test. 4. Couples who are known carriers of specific genetic conditions. 5. Anyone who wants the most information possible about their baby's health.

What Is Carrier Screening?

Carrier screening is a blood or saliva test that checks if you or your partner carry a gene for a recessive disorder, such as cystic fibrosis, spinal muscular atrophy, or sickle cell disease.

Being a 'carrier' means you have one copy of a mutated gene but do not have the condition yourself. If both parents are carriers of the same condition, there is a 25% (one in four) chance the baby will have the disorder. Many people are carriers without any family history of the disease, which is why we offer this to all couples planning a family. Ideally, this is done before you get pregnant (preconception), but it is very common to do it during the first trimester. If you are found to be a carrier, we then test your partner. This information allows us to prepare and, if necessary, offer further diagnostic testing during the pregnancy to see if the baby is affected.

Navigating the Emotional Impact of Testing

Deciding which tests to have—and waiting for the results—can be an emotionally taxing experience. There is no 'right' or 'wrong' choice, only what is best for your family and your peace of mind.

At Viva Eve, we often tell our patients: 'Tests provide information, but you provide the values.' Some couples want to know everything as soon as possible to prepare for a child with special needs or to make difficult decisions about the pregnancy. Others prefer to decline testing altogether to avoid unnecessary anxiety. Both are valid choices. Waiting for results can feel like an eternity. We are committed to getting you answers as quickly as possible and providing a 'warm friend' to talk to if the results are confusing. If a test comes back with unexpected news, we don't just hand you a report. We sit with you, explain the findings, and connect you with genetic counselors who can help you navigate the next steps. You are never alone in this process.
Common Questions

Frequently Asked Questions

No, all prenatal testing is optional. You have the right to accept or decline any screening or diagnostic test. Our role is to provide you with the information you need to make the decision that feels right for you and your partner.

NIPT results typically take about seven to 10 business days to return from the lab. We will call you as soon as the results are available to review the findings and answer any questions.

Most insurance plans cover NIPT for women over 35, but coverage for younger women and for carrier screening varies. Our billing team at Viva Eve can help you understand your specific coverage and any potential out-of-pocket costs.

Yes, NIPT can identify the presence of Y chromosomes to determine if the baby is biologically male or female with over 99% accuracy. This is often the earliest way to find out the gender, usually around 10 to 11 weeks.

A 'high risk' result is not a diagnosis. It simply means the chance of a condition is higher. If this happens, we will discuss the results in detail and offer diagnostic testing (like CVS or amniocentesis) to get a definitive answer.

Questions Before You Book? We’re Here to Help.

Finding the right provider is a big deal. Let's start with a conversation: your symptoms, your history, your options — whenever you're ready to talk.

Provide your contact info below and we'll give you a call within one business day to talk about your healthcare & next steps.