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Screening for fetal trisomy 21 in the first trimester of pregnancy: maternal serum free beta-hCG and fetal nuchal translucency thickness.
Noble PL, Abraha HD, Snijders RJ, Sherwood R, Nicolaides KH.
Ultrasound Obstet Gynecol 1995;6:390-5. -
Placental expression of alpha and beta subunits of human chorionic gonadotrophin in early pregnancies with Down's syndrome.
Brizot ML, Jauniaux E, Mckie AT, Farzaneh F, Nicolaides KH.
Hum Reprod 1995;10:2506-9.