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First-trimester markers of aneuploidy in women positive for HIV.
Savvidou M, Samuel I, Syngelaki A, Poulton M, Nicolaides K.
BJOG 2011;118:844-8. -
Maternal serum free beta-hCG at 10 to 14 weeks of gestation in trisomic twin pregnancies.
Noble PL, Snijders RJ, Abraha HD, Sherwood RA, Nicolaides KH.
BJOG 1997;104:741-3.