| Characteristic | No. of live births | Ankyloglossia | ||
|---|---|---|---|---|
| No. of cases | Rate per 1000 live births (95% CI) | Rate ratio (95% CI) | ||
| Maternal age, yr | ||||
| < 20 | 14 073 | 98 | 7.0 (5.7-8.5) | 1.01 (0.81-1.25) |
| 20-24 (ref) | 61 794 | 428 | 6.9 (6.3-7.6) | 1.00 (-) |
| 25-29 | 126 550 | 811 | 6.4 (6.0-6.9) | 0.93 (0.82-1.04) |
| 30-34 | 151 380 | 1 016 | 6.7 (6.3-7.1) | 0.97 (0.87-1.08) |
| 35-39 | 85 717 | 557 | 6.5 (6.0-7.1) | 0.94 (0.83-1.06) |
| ≥ 40 | 19 927 | 112 | 5.6 (4.6-6.8) | 0.81 (0.66-1.00) |
| Parity | ||||
| Nulliparous | 214 690 | 1 656 | 7.7 (7.3-8.1) | 1.38 (1.29-1.48) |
| Multiparous (ref) | 244 728 | 1 366 | 5.6 (5.3-5.9) | 1.00 (-) |
| Body mass index | ||||
| < 18 | 19 449 | 120 | 6.2 (5.1-7.4) | 0.94 (0.78-1.13) |
| 18-24 (ref) | 194 100 | 1 276 | 6.6 (6.2-6.9) | 1.00 (-) |
| 25-29 | 66 173 | 439 | 6.6 (6.0-7.3) | 1.01 (0.91-1.12) |
| ≥ 30 | 40 720 | 302 | 7.4 (6.6-8.3) | 1.13 (1.00-1.28) |
| Missing data | 139 003 | 885 | 6.4 (6.0-6.8) | 0.97 (0.89-1.05) |
| Plurality | ||||
| Singleton (ref) | 443 374 | 2 956 | 6.7 (6.4-6.9) | 1.00 (-) |
| Multiple | 16 071 | 66 | 4.1 (3.2-5.2) | 0.62 (0.49-0.79) |
| Gestational age,* wk | ||||
| 28-36 | 39 573 | 209 | 5.3 (4.6-6.0) | 0.75 (0.65-0.86) |
| 37-43 (ref) | 390 194 | 2 754 | 7.1 (6.8-7.3) | 1.00 (-) |
| Missing data | 27 832 | 55 | 1.9 (1.5-2.6) | 0.28 (0.21-0.37) |
| Infant sex | ||||
| Male | 237 230 | 1 957 | 8.2 (7.9-8.6) | 1.72 (1.60-1.85) |
| Female (ref) | 222 208 | 1 065 | 4.8 (4.5-5.1) | 1.00 (-) |
| Birth weight, g | ||||
| < 1500 | 4 711 | 10 | 2.1 (1.0-3.9) | 0.33 (0.18-0.62) |
| 1500-1999 | 7 003 | 17 | 2.4 (1.4-3.9) | 0.38 (0.24-0.61) |
| 2000-2499 | 18 469 | 66 | 3.6 (2.8-4.5) | 0.57 (0.45-0.72) |
| 2500-2999 | 69 407 | 406 | 5.8 (5.3-6.4) | 0.92 (0.85-1.00) |
| 3000-3499 (ref) | 163 673 | 1 075 | 6.6 (6.2-7.0) | 1.00 (-) |
| 3500-3999 | 137 549 | 967 | 7.0 (6.6-7.5) | 1.04 (0.99-1.09) |
| 4000-4499 | 46 636 | 393 | 8.4 (7.6-9.3) | 1.23 (1.13-1.34) |
| ≥ 4500 | 8 845 | 83 | 9.4 (7.5-11.6) | 1.48 (1.19-1.84) |
| Missing data | 3 152 | 5 | 1.6 (0.5-3.7) | 0.25 (0.10-0.60) |
| Year | ||||
| 2004 (ref) | 42 802 | 212 | 5.0 (4.3-5.7) | 1.00 (-) |
| 2005 | 43 147 | 233 | 5.4 (4.7-6.1) | 1.09 (0.90-1.31) |
| 2006 | 44 208 | 215 | 4.9 (4.2-5.6) | 0.98 (0.81-1.19) |
| 2007 | 46 617 | 258 | 5.5 (4.9-6.3) | 1.12 (0.93-1.34) |
| 2008 | 47 491 | 304 | 6.4 (5.7-7.2) | 1.29 (1.09-1.54) |
| 2009 | 47 762 | 306 | 6.4 (5.7-7.2) | 1.29 (1.09-1.54) |
| 2010 | 46 592 | 327 | 7.0 (6.3-7.8) | 1.41 (1.19-1.68) |
| 2011 | 47 025 | 396 | 8.4 (7.6-9.3) | 1.70 (1.44-2.01) |
| 2012 | 47 320 | 379 | 8.0 (7.2-8.8) | 1.62 (1.37-1.91) |
| 2013 | 46 481 | 392 | 8.4 (7.6-9.3) | 1.70 (1.44-2.01) |
| Overall | 459 445 | 3 022 | 6.6 (6.3-6.8) | - |
Note: CI = confidence interval, ref = reference category.
*Results for live births < 28 weeks' gestation not shown because of small number of cases (< 5).