BishopJDunstanFDJNixBReynoldsTM. The effects of gestational dating on the calculation of patient specific risks in Down's syndrome screening. Ann Clin Biochem1995; 32: 464–77
2.
WaldNCuckleHDensemJNanchahalKRoystonPChardT. Maternal serum screening in Down's syndrome in early pregnancy. BMJ1988; 297: 883–7
3.
WaldNJCuckleHSDensemJWKennardASmithD. Maternal serum screening for Down's syndrome: The effect of routine ultrasound scan determination of gestational age and adjustment for maternal weight. Br J Obstet Gynaecol1992; 99: 144–9