When is NIPT (non-invasive prenatal testing) done?

NIPT is typically performed from 9 weeks of pregnancy onward. A simple blood draw analyzes cell-free DNA from the placenta to screen for trisomy 21, 18, and 13, as well as sex chromosome conditions. Results are usually available within 5 to 10 days.

When is carrier screening done?

Carrier screening can be done before pregnancy or at any point in the first trimester. It tests for recessive conditions like cystic fibrosis, spinal muscular atrophy, and fragile X syndrome. Many US providers now offer expanded carrier screening panels that cover over 100 disorders.

When is the quad screen performed?

The quad screen is a maternal blood test done between 15 and 20 weeks of pregnancy, ideally at 16 to 18 weeks. It measures four substances to assess the risk of neural tube defects, Down syndrome, and trisomy 18.

When is chorionic villus sampling (CVS) done?

CVS is a diagnostic test performed between 10 and 13 weeks of pregnancy. A small sample of placental tissue is taken for chromosomal analysis. It is typically offered when first-trimester screening or NIPT shows an increased risk.

When is amniocentesis done?

Amniocentesis is usually performed between 15 and 20 weeks of pregnancy. A sample of amniotic fluid is collected to diagnose chromosomal conditions and neural tube defects. It is considered the gold standard for diagnostic confirmation.

When is NIPT (non-invasive prenatal testing) done?

NIPT is typically performed from 9 weeks of pregnancy onward. A simple blood draw analyzes cell-free DNA from the placenta to screen for trisomy 21, 18, and 13, as well as sex chromosome conditions. Results are usually available within 5 to 10 days.

When is carrier screening done?

Carrier screening can be done before pregnancy or at any point in the first trimester. It tests for recessive conditions like cystic fibrosis, spinal muscular atrophy, and fragile X syndrome. Many US providers now offer expanded carrier screening panels that cover over 100 disorders.

When is the quad screen performed?

The quad screen is a maternal blood test done between 15 and 20 weeks of pregnancy, ideally at 16 to 18 weeks. It measures four substances to assess the risk of neural tube defects, Down syndrome, and trisomy 18.

When is chorionic villus sampling (CVS) done?

CVS is a diagnostic test performed between 10 and 13 weeks of pregnancy. A small sample of placental tissue is taken for chromosomal analysis. It is typically offered when first-trimester screening or NIPT shows an increased risk.

When is amniocentesis done?

Amniocentesis is usually performed between 15 and 20 weeks of pregnancy. A sample of amniotic fluid is collected to diagnose chromosomal conditions and neural tube defects. It is considered the gold standard for diagnostic confirmation.

When Are Genetic Tests Done During Pregnancy?

Learn when genetic tests like NIPT, carrier screening & amniocentesis are offered in US pregnancy. Understand timing & options to order a prenatal screening panel.

Genetic tests during pregnancy are performed at specific windows to screen for or diagnose chromosomal conditions and inherited disorders. In the United States, routine genetic screening typically begins between 9 and 12 weeks of gestation with non-invasive prenatal testing (NIPT), also called cell-free DNA screening. The exact timing depends on the type of test, your provider's protocol, and whether you choose a comprehensive prenatal screening panel. This guide explains when each major test is offered, what it checks, and how to order an all-in-one panel online in 2026.

First-Trimester Screening (Weeks 9–13)

The first trimester offers the earliest window for genetic screening. Two main approaches are available:

Non-Invasive Prenatal Testing (NIPT)

NIPT analyzes cell-free DNA (cfDNA) fragments circulating in the mother's blood. It is the most sensitive screening test for trisomy 21 (Down syndrome), trisomy 18, and trisomy 13, and can also detect sex chromosome aneuploidies. NIPT can be performed as early as 9 weeks, though some labs recommend waiting until 10 weeks to ensure a sufficient fetal fraction (the proportion of fetal cfDNA in the sample). Results typically return within 5–10 calendar days.

First-Trimester Combined Screening

This includes a blood test (measuring PAPP-A and free beta-hCG) plus a nuchal translucency ultrasound. It is done between 11 weeks 0 days and 13 weeks 6 days. The combined screen estimates the risk for Down syndrome and trisomy 18. It is often used alongside NIPT for integrated screening protocols.

Carrier Screening (Any Time, Preferably Early)

Carrier screening tests for recessive genetic conditions that a parent may carry without showing symptoms. In the US, the American College of Obstetricians and Gynecologists (ACOG) recommends offering carrier screening for cystic fibrosis, spinal muscular atrophy, and fragile X syndrome, as well as hemoglobinopathies based on ethnicity. Expanded panels can screen for dozens of disorders. This test can be done before pregnancy or during the first trimester. Many women choose to include carrier screening as part of a comprehensive prenatal screening panel ordered online.

NIPT (cell-free DNA) – from 9 weeks
Carrier screening – before pregnancy or first trimester
First-trimester combined screen – 11–13 weeks
Quad screen – 15–20 weeks
Chorionic villus sampling (CVS) – 10–13 weeks (diagnostic)
Amniocentesis – 15–20 weeks (diagnostic)

Second-Trimester Screening (Weeks 15–20)

Quad Screen (Maternal Serum Screening)

The quad screen measures four markers: alpha-fetoprotein (AFP), hCG, estriol, and inhibin A. It screens for open neural tube defects (such as spina bifida), Down syndrome, and trisomy 18. The test is performed between 15 and 20 weeks, with optimal timing at 16–18 weeks. For women who did not have first-trimester screening, the quad screen is often used alone. It can also be part of integrated screening that combines first- and second-trimester results.

Amniocentesis (Diagnostic)

Amniocentesis is the gold standard for diagnosing chromosomal abnormalities. A needle is guided by ultrasound to collect amniotic fluid containing fetal cells. It is typically offered when NIPT, first-trimester screening, or the quad screen indicates increased risk. The procedure carries a small risk of miscarriage (roughly 1 in 900 in experienced centers). Results for common trisomies are available in a few days; full karyotype may take 1–2 weeks.

When Is Integrated Screening Used?

Integrated screening combines results from first-trimester blood tests and ultrasound with second-trimester quad screen markers. This approach provides a single, highly accurate risk estimate. The first blood draw occurs at 11–13 weeks, and the second at 15–20 weeks. A genetic counselor may help interpret the final risk score.

Summary Table: Timing of Common Genetic Tests

Test Type	Gestational Window	Purpose
NIPT (cell-free DNA)	From 9 weeks	Screen for trisomies 21, 18, 13; sex chromosome conditions
Carrier screening	Pre-pregnancy or first trimester	Identify recessive condition carriers (e.g., CF, SMA, fragile X)
First-trimester combined screen	11–13 weeks	Screen for Down syndrome and trisomy 18
Quad screen	15–20 weeks	Screen for neural tube defects, Down syndrome, trisomy 18
Chorionic villus sampling (CVS)	10–13 weeks	Diagnose chromosomal conditions (diagnostic)
Amniocentesis	15–20 weeks	Diagnose chromosomal conditions and neural tube defects (diagnostic)

Choosing the Right Test for You

Your decision depends on your age, family history, and personal preference. A genetic counselor can help you weigh the benefits of early NIPT versus integrated screening, or whether diagnostic testing like CVS or amniocentesis is right for you. Many US expectant parents now opt for a comprehensive prenatal screening panel that combines NIPT, carrier screening, and early anatomy assessment in a single order.

You can order a prenatal screening panel online and receive your results quickly, often within 5–10 business days. All tests are reviewed by board-certified genetic counselors and are available to US residents without needing a prior clinic visit.