The numbers of live births, numbers of live births with Down's syndrome and prevalences of Down's syndrome per 104 live births, during 1961–80 and 1971–80 by maternal age group for County Louth and Newry and Mourne District (reference incidences of Down's syndrome from Cuckle et al13)
| Maternal age group (y) | Reference incidence of live births with Down's syndrome (×10−4) | 1961–70 | 1971–80 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Live births (n) | Live births with Down's syndrome (n) | Prevalence of live births with Down's syndrome (×10−4) (n) | Live births (n) | Live births with Down's syndrome (n) | Prevalence of live births with Down's syndrome (×10−4) (n) | ||||
| County Louth: | |||||||||
| <20 | 6.2 | 502 | 0 | 0 | 994 | 2 | 20.1 | ||
| 20–24 | 6.7 | 3567 | 2 | 5.6 | 5090 | 3 | 5.9 | ||
| 25–29 | 8.8 | 4792 | 5 | 10.4 | 6327 | 4 | 6.3 | ||
| 30–34 | 13.8 | 3935 | 6 | 15.2 | 4165 | 6 | 14.4 | ||
| 35–39 | 39.3 | 2861 | 15 | 52.4 | 2163 | 12 | 55.5 | ||
| 40–44 | 138.2 | 1229 | 13 | 105.8 | 667 | 9 | 134.9 | ||
| ⩾45 | 404.2 | 102 | 7 | 686.3 | 53 | 1 | 188.7 | ||
| N/A4-150 | — | 24 | 0 | — | 30 | 0 | — | ||
| Newry and Mourne District:4-151 | |||||||||
| <20 | 6.2 | 737 | 0 | 0 | 985 | 0 | 0 | ||
| 20–24 | 6.7 | 4052 | 0 | 0 | 4533 | 1 | 2.2 | ||
| 25–29 | 8.8 | 4926 | 4 | 8.1 | 5117 | 5 | 9.8 | ||
| 30–34 | 13.8 | 3905 | 6 | 15.4 | 3438 | 7 | 20.4 | ||
| 35–39 | 39.3 | 2454 | 11 | 44.8 | 1697 | 8 | 47.1 | ||
| 40–44 | 138.2 | 954 | 12 | 125.8 | 556 | 11 | 197.8 | ||
| ⩾45 | 404.2 | 96 | 4 | 416.7 | 48 | 1 | 208.3 | ||