1. Northern Region Health Authority. A regionalfetal abnormality survey. First progress report. Newcastle upon Tyne: Northern Region Health Authority,1988
2. Report ofthe RCOG working party on routine ultrasound examination in pregnancy;of Obstericians, Royal College; Gynaecologists;London: The Royal College of Obstetricians and Gynaecologists,1984
3. Maternal serum screening for Down's syndrome in early pregnancy;Wald, N.J.; Cuckle, H.S.; Densem, J.W.;Br Med J,1988
4. representing;Campbell, A.G.M.; Hospital, Royal Aberdeen Children's; Foresterhill
5. representing;Cohen, S.J.; Hospital, Booth Hall Children's; Manchester