Comparison of the National Congenital Anomaly system (NCAS) with the National Down Syndrome Cytogenetic Register (NDSCR)
| Years of reporting | Information source | Percentage of anomalies on the NCAS compared with the NDSCR |
|---|---|---|
| 1974–87 | National estimates | 67 |
| 1990–93 | NDSCR | 48 |
| 1995–98 | NDSCR | 39–49 |