-
Dose dependency between cigarette consumption and reduced maternal serum PAPP-A levels at 11-13(+6) weeks of gestation.
Kagan KO, Frisova V, Nicolaides KH, Spencer K.
Prenat Diagn 2007;27:849-53. -
First-trimester screening for trisomy 21 in singleton pregnancies achieved by assisted reproduction.
Liao AW, Heath V, Kametas N, Spencer K, Nicolaides KH.
Hum Reprod 2001;16:1501-4.