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Sonographic screening for trisomy 13 at 11 to 13(+6) weeks of gestation.
Papageorghiou AT, Avgidou K, Spencer K, Nix B, Nicolaides KH.
Am J Obstet Gynecol 2006;194:397-401. -
Fetal heart rate at 10-14 weeks and birthweight.
Sebire NJ, Nayar R, Carvalho M, Soares W, Nicolaides KH.
BJOG 1997;104:1207-9.