Understanding Carrier Screening, NIPT, and the New Option of sgNIPT
Prenatal genetic screening has advanced rapidly over the past decade. What once involved limited testing for only a few disorders has evolved into safe, highly accurate blood-based screening that can identify genetic conditions before a baby is born. Today, two of the most common tools are carrier screening and non-invasive prenatal testing (NIPT) — and now a newer option, single-gene NIPT (sgNIPT), is becoming available in specific situations.
This article explains what these tests are, how they work, and when they may be recommended.
What Is Carrier Screening?
Carrier screening is a blood test performed before or during pregnancy to learn whether a person carries a genetic variant that could cause an inherited genetic disorder in a child. A carrier usually has no symptoms. But if both parents carry the same condition, there is typically a 25% chance the baby will be affected. You can also read more from the Cleveland Clinic.
Conditions commonly included in screening panels include:
- Cystic fibrosis
- Spinal muscular atrophy (SMA)
- Fragile X syndrome
- Hemoglobin disorders such as sickle cell disease and thalassemia
Modern expanded carrier screening can evaluate hundreds of genes at once, regardless of ancestry. Many medical organizations now recommend offering it to all patients.
What Is NIPT?
Non-invasive prenatal testing (NIPT) — also called cell-free DNA screening — is a blood test done during pregnancy. It analyzes tiny fragments of placental DNA floating in the mother’s bloodstream. Learn more from Stanford Medicine and Harvard Health.
NIPT primarily screens for chromosomal conditions, including:
NIPT has very high accuracy, and has become routine prenatal care worldwide. However, it is important to know that NIPT is a screening test — not a diagnostic test. If a result is abnormal, doctors may recommend amniocentesis or chorionic villus sampling (CVS) to confirm the diagnosis.
The American College of Obstetricians and Gynecologists (ACOG) recommends that NIPT be offered to all pregnant patients.
How Did These Tests Become the Standard of Care?
In the past, genetic screening was offered mainly to people with known risk factors. But research showed that many babies with genetic conditions are born into families with no history of disease. Combined with advances in DNA technology, this led medical organizations to recommend:
- Carrier screening for all prospective parents
- NIPT during pregnancy
These tools allow earlier detection and preparation, and often reduce the need for invasive testing.
What Is sgNIPT?
Single-gene non-invasive prenatal testing (sgNIPT) is a newer blood-based screening test during pregnancy. Instead of focusing on chromosomes, sgNIPT looks for specific single-gene disorders, many of which are autosomal recessive conditions (meaning both parents carry the same gene variant).
Examples of conditions sgNIPT may screen for include:
- Cystic fibrosis
- Spinal muscular atrophy (SMA)
- Sickle cell disease and other hemoglobin disorders
- Certain inherited metabolic disorders
Like NIPT, sgNIPT analyzes fragments of fetal and placental DNA in the mother’s bloodstream using advanced sequencing and statistical modeling.
A key reminder
sgNIPT is a screening test. Any high-risk result should be confirmed with diagnostic testing such as amniocentesis or CVS.
Because sgNIPT is newer, professional guidelines are still evolving, and accuracy continues to be studied in real-world practice.
ECWMG Recommendations
At ECWMG, we follow an evidence-based approach to genetic screening that supports patient choice and clear medical information.
⭐ Our preferred pathway is:
Before pregnancy
- Comprehensive carrier screening for the patient and partner
This gives the most accurate risk assessment and allows families to make decisions before pregnancy when time and options are broader.
During pregnancy
- Standard NIPT for chromosome conditions
This remains the gold-standard screening recommended by organizations such as ACOG and the Society for Maternal-Fetal Medicine.
When Might sgNIPT Be Considered?
Sometimes, patients are already pregnant, and/or partner testing is not available — for example, due to cost, limited access, travel, time constraints, or personal circumstances.
In these situations, sgNIPT may be a helpful additional screening option to estimate the baby’s risk of certain genetic disorders. It does not replace carrier screening, but it can provide information when traditional testing cannot be completed.
We discuss benefits, limitations, and next steps with every patient considering this option.
Screening vs Diagnosis — Why It Matters
Carrier screening, NIPT, and sgNIPT estimate risk — they do not confirm a diagnosis. If a screening test suggests a possible condition, your provider may recommend:
- Genetic counseling
- Targeted ultrasound
- Diagnostic testing (CVS or Amnio)
Learn more here:
Supporting You With Knowledge and Compassion
Genetic screening is ultimately about information and empowerment. For many families, results are reassuring. For others, screening allows time to prepare medically and emotionally, connect with specialists, or plan delivery at a hospital equipped for special care.
At ECWMG, we are committed to:
✔ offering medically sound options
✔ respecting your values and preferences
✔ explaining results clearly
✔ walking beside you every step of the way
If you have questions about carrier screening, NIPT, or sgNIPT, please speak with your ECWMG provider. Together, we’ll choose the testing strategy that works best for you and your family.
El Camino Women’s Medical Group offers the latest Minimally Invasive Solutions for gynecologic problems. Drs. Amy Teng, Erika Balassiano, Pooja Gupta, and Vivian Wan, all members of AAGL (American Association of Gynecologic Laparoscopy), are highly trained and experienced in the field of Minimally Invasive Gynecologic Surgery. Dr. Erika Balassiano has also completed a Minimally Invasive Gynecologic Surgery Fellowship under the supervision of world-renowned Dr. Camran Nezhat. Angel Wong, PA-C, is a physician assistant who sees patients for routine and lower-acuity care.
All of our physicians are El Camino Hospital doctors and operate and deliver at the Mountain View campus.
As part of El Camino Women’s Medical Group’s commitment to comprehensive care for women, we offer in-network mental health services with world-renowned psychiatrist Dr. Rania Awaad and experienced therapist Daniya Ahmed, LMFT. For women seeking to improve their health through a healthier diet, Mariam AlAgha, MS, is an excellent nutritionist with over a decade of success helping women achieve their health goals. Her services are also in network.
Serving Mountain View, Los Altos, Los Altos Hills, Atherton, Palo Alto, Redwood City, Burlingame, Saratoga, Cupertino, Sunnyvale, Los Gatos, Campbell, San Jose, Santa Clara, Silicon Valley, Milpitas, Fremont, South Bay, East Bay, and North Bay.