A screen negative result means that the risk of the baby being affected by Down syndrome or trisomy 18 is less than the cut-off. For example, the screen cut-off for Down syndrome with enhanced First Trimester Screening is 1 in 350 Therefore, any result lower than 1 in 350 is considered screen negative. The screen cut-off varies between screens and conditions.
A screen negative test can be reassuring but it is not diagnostic. Therefore, it is important to communicate that a screen negative test does not rule out the chance for the baby to have one of these conditions; a screen negative test can reduce the risk but does not eliminate it.
ALL pregnancies have a 2-3% risk for any birth defect wich may or may not be detected by prenatal screening.