Fetal fraction represents the proportion of cell-free fetal DNA circulating in a pregnant person’s blood. Non-Invasive Prenatal Testing (NIPT) analyzes this DNA to screen for certain chromosomal abnormalities in the developing fetus. For example, if a sample has a fetal fraction of 10%, it indicates that 10% of the cell-free DNA in the maternal blood sample originates from the placenta, which is generally representative of the fetal genome.
The quantity of fetal DNA present is critical for the accuracy and reliability of NIPT results. A sufficient amount ensures that the test has enough genetic material to analyze and minimizes the risk of false negative results. Historically, low amounts could lead to test failure, requiring a redraw and potentially delaying results. Understanding the proportion of this DNA helps clinicians assess the test’s validity and make informed decisions regarding patient care.
