-
Evidence-based obstetric ethics and informed decision-making by pregnant women about invasive diagnosis after first-trimester assessment of risk for trisomy 21.
Nicolaides KH, Chervenak FA, McCullough LB, Avgidou K, Papageorghiou A.
Am J Obstet Gynecol 2005;193:322-6. -
First trimester urine free beta hCG, beta core, and total oestriol in pregnancies affected by Down's syndrome: implications for first-trimester screening with nuchal translucency and serum free beta hCG.
Spencer K, Noble P, Snijders RJ, Nicolaides KH.
Prenat Diagn 1997;17:525-38.