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First-trimester maternal serum PAPP-A, SP1 and M-CSF levels in normal and trisomic twin pregnancies.
Bersinger NA, Noble P, Nicolaides KH.
Prenat Diagn 2003;23:157-62. -
Distribution of fetal erythroblasts in maternal blood after chorionic villous sampling.
Al-Mufti R, Hambley H, Farzaneh F, Nicolaides KH.
BJOG 2003;110:33-8.