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Prospective validation of first-trimester combined screening for trisomy 21.
Kagan KO, Etchegaray A, Zhou Y, Wright D, Nicolaides KH.
Ultrasound Obstet Gynecol 2009;34:14-8. -
One-stop clinic for assessment of risk for trisomy 21 at 11-14 weeks: a prospective study of 15 030 pregnancies.
Bindra R, Heath V, Liao A, Spencer K, Nicolaides KH.
Ultrasound Obstet Gynecol 2002;20:219-25.