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Cervicovaginal fibronectin and cervical length at 23 weeks of gestation: relative risk of early preterm delivery.
Heath VC, Daskalakis G, Zagaliki A, Carvalho M, Nicolaides KH.
BJOG 2000;107:1276-81. -
Maternal serum inhibin-A and free beta-hCG concentrations in trisomy 21 pregnancies at 10-14 weeks of gestation.
Noble PL, Wallace EM, Snijders RJ, Groome NP, Nicolaides KH.
BJOG 1997;104:367-71.