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Screening for trisomy 18 by maternal age, fetal nuchal translucency, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A.
Kagan KO, Wright D, Maiz N, Pandeva I, Nicolaides KH.
Ultrasound Obstet Gynecol 2008;32:488-92. -
Maternal serum activin A and inhibin A in trisomy 18 pregnancies at 10-14 weeks.
Spencer K, Liao AW, Ong CY, Flack NJ, Nicolaides KH.
Prenat Diagn 2001;21:571-4.