The Triple Test

Featured article: Wald NJ, Cuckle HS, Densem JW, Nanchahal K, Royston P, Chard T, et al. Maternal serum screening for Down's syndrome in early pregnancy. BMJ 1988;297:883–7.2The era of organized prenatal screening began in the mid-1970s with the discovery that maternal serum α-fetoprotein (AFP)3 could be used as a screening test for neural tube defects. This discovery led to work on how screening performance could be determined from AFP distributions in affected and unaffected pregnancies. To this end, the multiple of the median (MoM) was created (1) to allow for systematic interlaboratory AFP assay variation and factors such as gestational age. The multiple of the median was used in the 1977 UK Collaborative Study on Alpha-Fetoprotein in Relation to Neural-Tube Defects (2) and in a 1984 report on using low AFP concentrations in conjunction with maternal age in screening for Down syndrome (3). It was also used in our 1988 study described in the featured report. We combined AFP, unconjugated estriol, and human chorionic gonadotropin with maternal age to produce an estimate of the risk of having a Down syndrome pregnancy. This report …