Continuous variables (quartiles) | Mean birth weight (SD) | Small for gestational age N (%) | Preterm birth N (%) | Comparison group (≥ 37 weeks; ≥ 2500 grams) N (%) | ||||
---|---|---|---|---|---|---|---|---|
Cumulative traffic density/1000 (vehicles-km) | Â | Â | Â | Â | Â | Â | Â | Â |
   ≤ 261.0 | 3469 | (539) | 9441 | 22.4 | 7187 | 21.7 | 89628 | 25.6 |
   > 261.0 – 704.6 | 3427 | (526) | 10398 | 24.7 | 8105 | 24.4 | 87756 | 25.0 |
   > 704.6 – 1602.0 | 3398 | (564) | 10944 | 26.0 | 8628 | 26.0 | 86674 | 24.7 |
   > 1602.0 | 3368 | (569) | 11256 | 26.7 | 9207 | 27.7 | 85785 | 24.5 |
   Missing (688) | 3413 | (560) | 70 | 0.2 | 57 | 0.2 | 561 | 0.2 |
Distance to primary highways (meters) | Â | Â | Â | Â | Â | Â | Â | Â |
   ≤ 1107 | 3398 | (555) | 11067 | 26.3 | 8460 | 25.5 | 86888 | 24.8 |
   > 1107 – 2150 | 3403 | (565) | 10741 | 25.5 | 8496 | 25.6 | 87196 | 24.9 |
   > 2150 – 3745 | 3413 | (563) | 10482 | 24.9 | 8422 | 25.4 | 87529 | 25.0 |
   > 3750 | 3448 | (554) | 9819 | 23.3 | 7806 | 23.5 | 88791 | 25.3 |
% land use for recreation and conservation (open space) | Â | Â | Â | Â | Â | Â | Â | Â |
   ≤ 4.0 | 3363 | (568) | 11184 | 26.6 | 8905 | 26.8 | 81668 | 23.3 |
   > 4.0 – 9.4 | 3403 | (567) | 10861 | 25.8 | 8711 | 26.3 | 86966 | 24.8 |
   > 9.4 – 17.8 | 3447 | (547) | 9658 | 22.9 | 7182 | 21.6 | 85787 | 24.5 |
   > 17.8 | 3458 | (546) | 9210 | 21.9 | 7328 | 22.1 | 87770 | 25.0 |
   Missing (10470) | 3319 | (597) | 1196 | 2.8 | 1058 | 3.2 | 8213 | 2.3 |
Median household income (in US $) | Â | Â | Â | Â | Â | Â | Â | Â |
   ≤ 46336 | 3303 | (581) | 12853 | 30.5 | 10736 | 32.4 | 83081 | 23.7 |
   > 46336 – 62773 | 3406 | (564) | 10984 | 26.1 | 8405 | 25.3 | 86917 | 24.8 |
   > 62773 – 78583 | 3467 | (547) | 9778 | 23.2 | 7253 | 21.9 | 89304 | 25.5 |
   > 78583 | 3486 | (526) | 8494 | 20.2 | 6790 | 20.5 | 91102 | 26.0 |