Non-Invasive Prenatal Test
What is NIPT
NIPT is a prenatal screening test that can be performed as early as 10 weeks of pregnancy using a single blood draw. Prenatal diagnostic tests such as amniocentesis and CVS diagnose the presence of chromosomal conditions. They are typically performed later in pregnancy and are associated with a small risk of pregnancy loss.
What does NIPT test for?
NIPT or NIPS (non-invasive prenatal screening) looks at fragments of DNA (cell-free DNA or cfDNA) in your blood during pregnancy to provide accurate information about the likelihood of chromosomal conditions that can impact your baby’s health. NIPT can be performed as early as 10 weeks of pregnancy and screens for the most common chromosomal conditions such as trisomy 21 (Down syndrome), trisomy 18, trisomy 13, sex chromosome aneuploidies (SCA) and 22q11.2 microdeletion. Some NIPTs such as the Harmony prenatal test also provide the option of reporting the sex of your baby.
Who should consider NIPT?
Previously, NIPT was offered only to women with pregnancies at high risk for chromosomal conditions, such as women over 35 or with a family history of chromosomal conditions. However, professional societies such as The American College of Medical Genetics and Genomics (ACMG) now recommend that doctors inform all pregnant women regardless of age or risk about the fact that cfDNA-based NIPT is the most sensitive screening option for trisomy 21, trisomy 18 and trisomy 13.1 The International Society for Prenatal Diagnosis (ISPD) considers NIPT as appropriate to be offered to all pregnant women as a primary screening test.2
How safe is NIPT?
NIPT is performed with a simple blood draw from the mother, so it is considered very safe.
How accurate is NIPT?
cfDNA-based NIPT is recognized as the most sensitive screening option for trisomy 21 (Down syndrome), trisomy 18, and trisomy 13.1 The Harmony prenatal test has been shown to have superior accuracy in a direct comparison to traditional first trimester screening in over 15,000 women.3 However, not all NIPTs perform with the same accuracy. NIPT for very rare conditions, such as those offered in microdeletion panels, have unclear accuracy.
What are the differences between NIPT and diagnostic tests?
NIPT is a blood test that provides you an opportunity to obtain accurate information about the likelihood for the most common chromosomal conditions. It can be performed as early as 10 weeks of pregnancy without posing a risk to the baby. Because NIPT is a prenatal screening test it cannot rule out the possibility of chromosomal conditions. In the case of a high probability result, your care provider may offer follow up testing to confirm a diagnosis.
Prenatal diagnostic tests such as amniocentesis or chorionic villus sampling (CVS) require collection of the baby’s cells in the amniotic fluid or the placenta with a needle and are therefore considered invasive. Diagnostic tests provide a definitive answer; however, they pose a slight chance of loss of pregnancy due to the procedure itself.4
How can I get an NIPT?
Talk to your healthcare provider about your prenatal testing options. Some NIPTs such as the Harmony test are available to women of any age, in singleton, twin and egg donor pregnancies. Your doctor will be able to order the test for you.
- Gregg et al. Genetics in Medicine 2016 Oct; 18(10):1056-65.
- Benn et al. Prenat Diagn. 2015; 35: 725–734.
- Norton et al. New England J of Medicine. 2015; 372(17):1589-1597.
- Akolekar et al. Ultrasound Obstet Gynecol 2015; 45:16-26.