![]() ![]() 5 In subsequent years there was a gradual acceptance of the association, as well as an eventual understanding that the extent of AFP reduction differed according to the type of aneuploidy. confirmed that this holds for Down syndrome. published the association of low maternal serum α-fetoprotein (AFP) with an increased risk of aneuploidy in general, 4 and Cuckle et al. Much has been written over the years describing the state of the art at given times and extensive detail regarding previous eras is not repeated here. 1, 2, 3, 4 Incorporation of these approaches has been haphazard with huge variability around the world and even within countries. Over the past 25 years, there have been several generations of “best available” approaches which have increasingly improved the statistics of screening. 3, 4 Using a cut-off maternal age of 35, a 30–40% sensitivity and 90–95% specificity (or 5–10% false-positive rate) were the best available statistics throughout the 1970s and early 1980s. These have improved the sensitivity (proportion of aneuploidy pregnancies at high risk or detection rate) and specificity (proportion of unaffected pregnancies not at high risk). Over the past three decades, attempts have been made to refine the assessment of an individual woman’s risk using biochemical and ultrasound markers within pregnancy. 1, 2, 3 In all countries, women above a fixed cut-off age were regarded as at high enough risk of aneuploidy to warrant the costs and hazards of performing an invasive diagnostic procedure. The association of aneuploidy with advanced maternal age was the be all and end all of prenatal assessment for half a century. ![]()
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