Figure 1. When prenatal testing for T21 began some 20 years ago, it was usually limited to women 35 years or older. Amniocentesis and karyotyping provided diagnostic tests. Today, maternal serum ...

Some centres report the use of ‘early amniocentesis’ as a diagnostic procedure (⩽15 weeks gestation), with the laboratories performing the greatest number of early amniocenteses accounting ...

1 Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, UK Correspondence to Joan K Morris, ...