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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. -
First trimester prenatal diagnosis of trisomy 21 in discordant twins using fetal nuchal translucency thickness and maternal serum free beta-hCG and PAPP-A.
Spencer K, Nicolaides KH.
Prenat Diagn 2000;20:683-4. -
Maternal serum concentrations of pregnancy associated plasma protein A and pregnancy specific B-1 glycoprotein in multifetal pregnancies before and after fetal reduction.
Abbas A, Sebire NJ, Johnson M, Bersinger N, Nicolaides KH.
Hum Reprod 1996;11,900-2.