Congenital anomalies studied in the National Congenital Anomaly System (NCAS) for England and Wales and four local congenital anomaly registers in England, 1991-9. Values are numbers of cases unless otherwise indicated

Anomaly group and subgroups NCAS Local registries (terminations excluded)* NCAS cases as % of local registry cases (terminations excluded)* All cases in registries (terminations included)* NCAS cases as % of all registry cases* All cases 2483 6240 40 9245 27 All chromosomal anomalies: 555 1641 34 2927 19 Down's syndrome 428 834 51 1496 29 All non-chromosomal anomalies 1928 4599 42 6273 31 Some specific non-chromosomal anomalies: All neural tube defects 119 176 68 1041 11 Spina bifida 84 112 75 457 18 Cardiac anomalies (excluding ventricular septal defects) 241 1800 13 2050 12 Hypoplastic left heart 19 98 19 181 11 Fallot's tetralogy 26 140 19 151 17 Cleft lip 452 547 83 601 75 Cleft palate 208 292 71 307 68 Digestive system (fistulas and atresias) 188 415 45 471 40 Gastroschisis 58 132 44 146 40 Exomphalos 28 58 48 106 26 Diaphragmatic hernia 29 85 34 123 24 Cystic kidneys 82 299 27 393 21 Limb reduction 217 246 88 296 73

^* One of the four local registers provided data for 1994-9 only.

Includes anomalies coded with the following ICD10 codes: Q90-94, Q96-99.

Includes anomalies coded with the following ICD10 codes: Q00-03, Q041-042, Q05, Q110-112, Q160, Q172, Q20, Q211-219, Q22-23, Q25-26, Q300-348, Q36-37, Q35, Q390-394, Q41, Q42, Q600-605, Q61, Q641-643, Q645, Q71-73, Q77, Q78, Q790-793.

Analysis limited to 1995-9 to achieve coding comparability between NCAS and local register data.