1. Antenatal screening for Down syndrome;Wald;Lancet,1988
2. Antenatal screening for Down syndrome;Wald;Prog Clin Biol Res,1995
3. Efficacy of screening for fetal Down syndrome in the United States from 1974 to 1997;Egan;Obstet Gynecol,2000
4. Estimating a woman’s risk of having a pregnancy associated with Down’s syndrome using her age and serum alpha-fetoprotein level;Cuckle;Br J Obstet Gynaecol,1987
5. Chromosome abnormalities investigated by non-invasive prenatal testing account for approximately 50% of fetal unbalances associated with relevant clinical phenotypes;Grati;Am J Med Genet A,2010