Table 3.
Adjusted odds ratios (95% confidence intervals) for COPD risk associated with number of pregnancies and pregnancy losses, stratified by baseline characteristics.
| Number of | Number of | Pregnancy | p for | Number of | Number of | Pregnancy loss | p for | |
|---|---|---|---|---|---|---|---|---|
| participants | events | OR (95% CI) | interaction | participants | events | OR (95% CI) | interaction | |
| Age | 0.75 | 0.12 | ||||||
| 30–39.9 | 48,041 | 444 | 1.03 (0.46, 2.33) | 47,399 | 307 | 1.37 (1.11, 1.70)** | ||
| 40–49.9 | 93,549 | 1,295 | 0.81 (0.49, 1.36) | 92,726 | 911 | 1.23 (1.09, 1.40)** | ||
| 50–59.9 | 93,867 | 2,264 | 0.90 (0.58, 1.39) | 93,118 | 1,454 | 1.16 (1.06, 1.27)** | ||
| ≥60 | 67,053 | 2,663 | 0.76 (0.55, 1.06) | 66,339 | 1,642 | 1.16 (1.06, 1.26)** | ||
| BMI | 0.59 | |||||||
| <25 | 198,799 | 4,407 | 0.80 (0.61, 1.04) | 196,774 | 2,816 | 1.19 (1.12, 1.27)** | 0.82 | |
| ≥25 | 103,711 | 2,259 | 0.91 (0.59, 1.39) | 102,808 | 1,498 | 1.18 (1.08, 1.29)** | ||
| Region | 0.22 | |||||||
| Rural | 167,682 | 3,367 | 0.75 (0.54, 1.04) | 166,530 | 1,842 | 1.08 (0.99, 1.17) | 0.14 | |
| Urban | 134,828 | 3,299 | 0.90 (0.67, 1.23) | 133,052 | 2,472 | 1.24 (1.12, 1.37)** | ||
| Educational level | 0.39 | |||||||
| Elementary school and below | 171,580 | 4,473 | 0.89 (0.65, 1.21) | 170,305 | 2,644 | 1.19 (1.10, 1.28)** | 0.15 | |
| Middle and high school | 117,491 | 1,903 | 0.86 (0.58, 1.29) | 116,249 | 1,448 | 1.08 (0.93, 1.25) | ||
| University and above | 13,439 | 290 | 0.54 (0.30, 0.96)* | 13,028 | 222 | 0.98 (0.65, 1.48) | ||
| Household income | 0.20 | 0.76 | ||||||
| <5,000 | 30,720 | 1,068 | 1.41 (0.73, 2.76) | 30,367 | 554 | 1.19 (1.05, 1.35)** | ||
| 5,000–19,999 | 148,702 | 2,915 | 0.76 (0.55, 1.04) | 147,173 | 1,854 | 1.22 (1.13, 1.32)** | ||
| ≥20,000 | 123,088 | 2,683 | 0.76 (0.53, 1.09) | 12,204 | 1,906 | 1.16 (1.07, 1.27)** | ||
| MET | 0.63 | 0.06 | ||||||
| <20 | 177,743 | 4,415 | 0.89 (0.68, 1.17) | 175,745 | 2,911 | 1.17 (1.09, 1.25)** | ||
| 20–29.9 | 58067 | 1,114 | 0.81 (0.44, 1.47) | 57,617 | 689 | 1.13 (0.997, 1.29) | ||
| ≥30 | 66,700 | 1137 | 0.65 (0.37, 1.13) | 66,220 | 714 | 1.24 (1.09, 1.41)** | ||
| Smoking status | 0.40 | 0.21 | ||||||
| Never smoker | 287,180 | 5,996 | 0.80 (0.64, 1.02) | 284,454 | 3,909 | 1.19 (1.11, 1.27)** | ||
| Ever smoker | 15,330 | 670 | 1.10 (0.53, 2.26) | 15,128 | 405 | 0.95 (0.77, 1.16) | ||
| Alcohol consumption | 0.03 | 0.17 | ||||||
| Never drinker | 192,323 | 4,658 | 1.02 (0.75, 1.38) | 190,625 | 2,945 | 1.18 (1.09, 1.27)** | ||
| Ever drinker | 110,187 | 2,008 | 0.62 (0.44, 0.86)** | 108,957 | 1,369 | 1.08 (0.95, 1.23) | ||
| Tuberculosis | 0.24 | 0.36 | ||||||
| No | 299,087 | 6,431 | 0.83 (0.66, 1.04) | 296,254 | 4,154 | 1.19 (1.13, 1.25)** | ||
| Yes | 3,423 | 235 | 1.66 (0.60, 4.61) | 3,328 | 160 | 1.14 (0.84, 1.54) |
Adjusted for age, region, BMI, level of highest education, annual household income, physical activity, smoking, and alcohol consumption. Analyses for pregnancy loss, spontaneous abortion, induced abortion, and stillbirth, were additionally adjusted for number of live births, and (where appropriate) number of spontaneous abortions, induced abortions, and stillbirths. Analyses for pregnancy, pregnancy loss, spontaneous abortion, induced abortion, and stillbirth, respectively, are among women with at least one pregnancy or at least one pregnancy loss, spontaneous abortion, induced abortion, stillbirth BMI, body mass index; MET, metabolic equivalent of tasks. *p < 0.05; **p < 0.01.