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Cell-free DNA analysis for trisomy risk assessment in first-trimester twin pregnancies.
Gil MM, Quezada MS, Bregant B, Syngelaki A, Nicolaides KH.
Fetal Diagn Ther 2014;35:204-11. pdf -
Ductus venosus in the first trimester: contribution to screening of chromosomal, cardiac defects and monochorionic twin complications.
Maiz N, Nicolaides KH.
Fetal Diagn Ther 2010;28:65-71.