Measures of birth weight and gestational age by population chlorination proportion, color, maternal age, parity, place of birth, centrality, population density and industrial profile in Norway 1993–95
| Determinant | n |
Birth weight (g) mean (95% CI) | Low birth weight (<2500 g) prevelence (95% CI) |
Small for gestational age prevelence (95% CI) |
Preterm delivery (<37 weeks) prevelence (95% CI) |
| Total | 137145 | 3537 (3534 to 3540) | |||
| Exposure category: | |||||
| No chlorination, low colour | 19480 | 3544 (3535 to 3552) | 4.5 (4.24 to 4.83) | 4.5 (4.18 to 4.76) | 6.7 (6.37 to 7.11) |
| No chlorination, high colour | 11836 | 3573 (3562 to 3584) | 4.4 (4.02 to 4.75) | 4.3 (3.89 to 4.61) | 6.0 (5.58 to 6.50) |
| Chlorination, low colour | 34063 | 3546 (3540 to 3552) | 4.5 (4.32 to 4.76) | 4.5 (4.24 to 4.68) | 6.4 (6.17 to 6.72) |
| Chlorination, high colour | 71766 | 3525 (3521 to 3530) | 4.7 (4.52 to 4.83) | 4.6 (4.41 to 4.72) | 6.4 (6.19 to 6.56) |
| Maternal age: | |||||
| <20 | 3234 | 3437 (3417 to 3458) | 5.8 (5.00 to 6.59) | 5.7 (4.86 to 6.46) | 8.8 (7.70 to 9.82) |
| 20–34 | 115577 | 3540 (3536 to 3543) | 4.4 (4.25 to 4.49) | 4.3 (4.16 to 4.39) | 6.1 (5.96 to 6.25) |
| ⩾35 | 18334 | 3540 (3530 to 3549) | 5.8 (5.49 to 6.16) | 5.7 (5.39 to 6.06) | 7.9 (7.53 to 8.35) |
| Parity2-150 | |||||
| 0 | 56000 | 3447 (3442 to 3452) | 5.8 (5.64 to 6.03) | 5.7 (5.52 to 5.90) | 7.5 (7.24 to 7.70) |
| 1 | 48933 | 3590 (3585 to 3596) | 3.6 (3.40 to 3.73) | 3.5 (3.34 to 3.66) | 5.4 (5.20 to 5.61) |
| 2 | 22657 | 3622 (3614 to 3630) | 3.7 (3.44 to 3.94) | 3.6 (3.35 to 3.84) | 5.8 (5.47 to 6.11) |
| ⩾3 | 8575 | 3600 (3586 to 3614) | 4.7 (4.22 to 5.11) | 4.6 (4.15 to 5.04) | 7.0 (6.37 to 7.51) |
| Born in university clinic: | |||||
| No | 114317 | 3546 (3543 to 3550) | 4.5 (4.33 to 4.57) | 4.4 (4.24 to 4.48) | 6.3 (6.15 to 6.44) |
| Yes | 22828 | 3492 (3484 to 3500) | 5.3 (5.03 to 5.61) | 5.2 (4.90 to 5.47) | 7.0 (6.66 to 7.35) |
| Centrality: | |||||
| Low | 45399 | 3548 (3543 to 3554) | 4.4 (4.26 to 4.64) | 4.4 (4.17 to 4.55) | 6.4 (6.14 to 6.62) |
| Medium | 32617 | 3539 (3533 to 3546) | 4.7 (4.50 to 4.96) | 4.6 (4.41 to 4.86) | 6.4 (6.16 to 6.73) |
| High | 59129 | 3528 (3523 to 3532) | 4.6 (4.46 to 4.80) | 4.5 (4.36 to 4.70) | 6.4 (6.22 to 6.63) |
| Population density (urban/total population (%)): | |||||
| <20 | 7134 | 3567 (3552 to 3581) | 4.5 (4.01 to 5.00) | 4.4 (3.93 to 4.88) | 6.6 (5.94 to 7.16) |
| 20–39.9 | 12721 | 3571 (3561 to 3582) | 4.1 (3.77 to 4.47) | 4.1 (3.73 to 4.42) | 5.7 (5.26 to 6.11) |
| 40–59.9 | 19854 | 3557 (3548 to 3565) | 4.4 (4.11 to 4.68) | 4.3 (4.01 to 4.58) | 6.6 (6.23 to 6.96) |
| 60–79.9 | 29359 | 3540 (3532 to 3546) | 4.7 (4.41 to 4.89) | 4.6 (4.32 to 4.80) | 6.4 (6.12 to 6.72) |
| ⩾80 | 68077 | 3521 (3517 to 3526) | 4.7 (4.57 to 4.89) | 4.6 (4.46 to 4.78) | 6.5 (6.29 to 6.68) |
| Industrial profile: | |||||
| Low | 1633 | 3565 (3536 to 3594) | 4.0 (3.03 to 4.93) | 3.8 (2.87 to 4.73) | 7.5 (6.21 to 8.89) |
| Medium | 5839 | 3552 (3536 to 3568) | 4.4 (3.88 to 4.93) | 4.3 (3.80 to 4.80) | 6.1 (5.42 to 6.71) |
| High | 129673 | 3536 (3533 to 3540) | 4.6 (4.50 to 4.73) | 4.5 (4.40 to 4.63) | 6.4 (6.28 to 6.56) |
↵2-150 Missing information 980.