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First-trimester screening for neural tube defects using alpha-fetoprotein.
Bredaki FE, Poon LC, Birdir C, Escalante D, Nicolaides KH.
Fetal Diagn Ther 2012;31:109-14. -
First trimester maternal serum AFP and total hCG in aneuploidies other than trisomy 21.
Spencer K, Heath V, Flack N, Ong C, Nicolaides KH.
Prenat Diagn 2000;20:635-9.