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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. -
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.