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Maternal serum activin A and inhibin A in trisomy 18 pregnancies at 10-14 weeks.
Spencer K, Liao AW, Ong CY, Flack NJ, Nicolaides KH.
Prenat Diagn 2001;21:571-4. -
Cardiac defects in 1st-trimester fetuses with trisomy 18.
Hyett JA, Moscoso G, Nicolaides KH.
Fetal Diagn Ther 1995;10:381-6.