Non-invasive prenatal testing (NIPT) is a screening test based on a blood sample taken from the mother that can be performed from about the 10th week of pregnancy. Part of the cell-free DNA circulating in the mother's blood comes from the placenta; NIPT analyzes this DNA to assess the likelihood of the most common chromosome number abnormalities in the fetus.
What does it screen for?
- Trisomy 21 (Down syndrome)
- Trisomy 18 (Edwards syndrome)
- Trisomy 13 (Patau syndrome)
- Sex chromosome abnormalities (depending on the scope of the test)
A screening test, not a diagnostic test
NIPT is a highly sensitive screening test; it does not give a definitive diagnosis. When a high-risk result is obtained, confirmation with an invasive diagnostic test such as chorionic villus sampling (CVS) or amniocentesis is recommended. A low-risk result markedly reduces the likelihood of the relevant abnormalities but does not rule them out entirely.
Who is it suitable for?
NIPT can be performed in singleton and twin pregnancies. It is particularly valuable in cases of advanced maternal age, increased risk on first-trimester screening, or a family history of chromosomal abnormality. Genetic counseling before and after the test is important for interpreting the result correctly.
