The past quarter century has been witness to a series of remarkable advances in the screening of pregnancies for aneuploidy, particularly in the identification of those with Down syndrome. During the 1970s and early 1980s, advanced maternal age, defined as over 35 years, was the only means by which the general population was assessed as to risk of a fetal chromosomal abnormality. In the late 1990s and early 2000s, aneuploidy screening shifted to the first trimester with the ‘combined’ test, which uses ultrasound measurement of nuchal translucency thickness (NT) together with maternal serum concentration of placental proteins human chorionic gonadotropin (hCG) (free β, intact or total) and pregnancyassociated plasma protein-A (PAPP-A). The clinical use of NIPT to screen high-risk patients for fetal aneuploidy is becoming increasingly common.