OR of frequent pregnancy loss (≥2 or ≥3 times) from childhood secondhand smoke exposure in female never smokers by logistic regression (after PSM)
| OR (95% CI) | ||||
|---|---|---|---|---|
| Number (%) | Crude model | Model 1 | Model 2 | |
| Pregnancy loss ≥2 | ||||
| Number of smokers | ||||
| None (reference) | 360 (4.6) | 1 | 1 | 1 |
| 1 smoker | 293 (4.9) | 1.07 (0.91 to 1.25) | 1.09 (0.93 to 1.27) | 1.07 (0.91 to 1.26) |
| ≥2 smokers | 104 (5.6) | 1.23 (0.99 to 1.54) | 1.27 (1.01 to 1.59)* | 1.25 (1.00 to 1.57)* |
| P for trend | 0.08 | 0.04 | 0.06 | |
| Frequency of exposure | ||||
| None (reference) | 360 (4.6) | 1 | 1 | 1 |
| <5 times/week | 72 (3.7) | 0.80 (0.62 to 1.04) | 0.84 (0.65 to 1.08) | 0.84 (0.65 to 1.09) |
| ≥5 times/week | 325 (5.5) | 1.21 (1.04 to 1.41)* | 1.22 (1.05 to 1.43)* | 1.20 (1.03 to 1.40)* |
| P for trend | 0.02 | 0.01 | 0.03 | |
| Pregnancy loss ≥3 | ||||
| Number of smokers | ||||
| None (reference) | 108 (1.4) | 1 | 1 | 1 |
| 1 smoker | 97 (1.6) | 1.18 (0.90 to 1.56) | 1.19 (0.91 to 1.57) | 1.18 (0.89 to 1.55) |
| ≥2 smokers | 28 (1.5) | 1.10 (0.72 to 1.67) | 1.12 (0.74 to 1.71) | 1.09 (0.72 to 1.67) |
| P for trend | 0.39 | 0.33 | 0.46 | |
| Frequency of exposure | ||||
| None (reference) | 108 (1.4) | 1 | 1 | 1 |
| <5 times/week | 18 (0.9) | 0.67 (0.41 to 1.11) | 0.70 (0.42 to 1.15) | 0.70 (0.42 to 1.15) |
| ≥5 times/week | 107 (1.8) | 1.32 (1.01 to 1.73)* | 1.33 (1.02 to 1.74)* | 1.30 (1.00 to 1.71)* |
| P for trend | 0.05 | 0.04 | 0.06 | |
*p<0.05.
Model 1: Adjusted for age.
Model 2: Adjusted for age, education, past occupational dust exposure, past home fuel exposure, oral contraceptive, total pregnancy times, adulthood passive smoke exposure, age at first pregnancy and age at first menarche.