Spontaneous abortions (miscarriages) and odds ratios (95% confidence limits) of associations with lifetime SHS exposure among 40 850 never-smoking women* who were pregnant at least once
| Never-smokers exposed to secondhand smoke | Spontaneous abortions | Crude OR | Adjusted OR† |
|---|---|---|---|
| n (%) of total | (95% CI) | (95% CI) | |
| No SHS exposure | 1134 (29.9) of 3789 | 1.0 (Reference) | 1.0 (Reference) |
| Any: | |||
| Childhood only | 730 (30.4) of 2399 | 1.02 (0.92 to 1.14) | 1.04 (0.93 to 1.17) |
| Adult home only | 861 (31.5) of 2735 | 1.08 (0.97 to 1.20) | 1.03 (0.92 to 1.15) |
| Adult work only | 1481 (30.6) of 4846 | 1.03 (0.94 to 1.13) | 1.04 (0.94 to 1.14) |
| Childhood+adult home | 1457 (32.1) of 4541 | 1.11 (1.01 to 1.21) | 1.08 (0.98 to 1.19) |
| Childhood+adult work | 1165 (28.8) of 4042 | 0.95 (0.86 to 1.04) | 0.97 (0.87 to 1.07) |
| Adult home+adult work | 1818 (32.2) of 5644 | 1.11 (1.02 to 1.22) | 1.08 (0.98 to 1.18) |
| Childhood+adult home+work | 4143 (32.2) of 12 854 | 1.11 (1.03 to 1.20) | 1.10 (1.02 to 1.20) |
| Quantified SHS exposure: | |||
| No childhood+any adult | 4133 (31.5) of 13 125 | 1.08 (0.99 to 1.16) | 1.05 (0.97 to 1.14) |
| Childhood <10 years+any adult | 1120 (30.7) of 3653 | 1.04 (0.94 to 1.14) | 1.01 (0.91 to 1.11) |
| Childhood ≥10 years+adult home<20 years+adult work <10 years | 2927 (30.8) of 9506 | 1.04 (0.96 to 1.13) | 1.06 (0.97 to 1.15) |
| Childhood ≥10 years+adult home <20 years+adult work ≥10 years | 1123 (29.6) of 3789 | 0.99 (0.89 to 1.09) | 1.00 (0.90 to 1.10) |
| Childhood ≥10 years+adult home ≥20 years+adult work <10 years | 1197 (33.8) of 3538 | 1.20 (1.08 to 1.32) | 1.14 (1.03 to 1.26) |
| Childhood ≥ 10 years+adult home ≥ 20 years+adult work ≥ 10 years | 1046 (33.5) of 3125 | 1.18 (1.06 to 1.30) | 1.17 (1.05 to 1.30) |
| p Value for trend | 0.007 | 0.008 | |
Numbers in bold are significant at the p<0.05 level.
*39 206 after adjustment of categorical exposure; 38 910 after adjustment of quantified exposure.
†Adjusted for mean Body Mass Index (age 18–50 years), age cohort at baseline, ethnicity, education, alcohol intake, parity and oral contraceptive use (ever).
SHS, secondhand smoke