Noninvasive prenatal testing (NIPT), also known as noninvasive prenatal screening (NIPS) or cell-free DNA screening (cfDNA), is a blood test that can help determine the risk of a fetus being born with certain chromosomal abnormalities. NIPT analyzes small fragments of DNA, called cell-free DNA (cfDNA), that circulate in a pregnant woman's blood. These fragments are different from most DNA because they are free-floating and not within cells. During pregnancy, the placenta releases some of its DNA into the bloodstream, so the blood contains both the mother's DNA and some from the placenta.

 

NIPT measures this DNA to identify factors that may increase the risk of the fetus having a chromosomal difference. For example, if NIPT finds more DNA than expected for chromosomes 21, 18, or 13, it could mean that the baby has Down's syndrome, Edward's syndrome, or Patau's syndrome. NIPT can also reveal if the baby is Rh positive or negative, which may help determine if the mother will need a RhoGAM shot during pregnancy. 

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NIPT is highly accurate, but it's not 100% accurate. The detection rate is usually between 90–99% for high-risk pregnancies with only one baby, and false positive rates are less than 1%. An abnormal NIPT result doesn't necessarily mean there's a problem with the pregnancy, but a doctor may recommend diagnostic testing to confirm the result. These tests include chorionic villus sampling (CVS) or amniocentesis. ​

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