Table II.
Association between female active smoking history at baseline and fecundability.
| No. of cycles | No. of Pregnancies | Unadjusted FR (95% CI) | Adjusteda,c FR (95% CI) | Adjustedb,c FR (95% CI) | |
|---|---|---|---|---|---|
| Never smokers | 16 431 | 2431 | 1.00 (Reference) | 1.00 (Reference) | 1.00 (Reference) |
| Former smokers | 3575 | 447 | 0.87 (0.79, 0.96) | 0.89 (0.81, 0.98) | 0.89 (0.81, 0.98) |
| Current occasional smokers | 921 | 100 | 0.78 (0.64, 0.94) | 0.84 (0.70, 1.02) | 0.88 (0.73, 1.06) |
| Current regular smokers | 1403 | 153 | 0.81 (0.68, 0.95) | 0.87 (0.74, 1.02) | 0.90 (0.77, 1.07) |
| Former smokers | |||||
| Time since regular smoking (years) | |||||
| <1 | 274 | 36 | 0.89 (0.65, 1.22) | 0.96 (0.72, 1.28) | 0.99 (0.74, 1.32) |
| 1 | 372 | 51 | 0.96 (0.73, 1.25) | 0.93 (0.72, 1.21) | 0.86 (0.67, 1.12) |
| 2–4 | 1094 | 135 | 0.84 (0.72, 0.99) | 0.86 (0.73, 1.00) | 0.90 (0.77, 1.05) |
| ≥5 | 1835 | 225 | 0.86 (0.76, 0.98) | 0.90 (0.79, 1.03) | 0.88 (0.77, 1.01) |
| Intensity (cigarettes/day) | |||||
| <5 | 1275 | 168 | 0.92 (0.79, 1.06) | 0.93 (0.81, 1.08) | 0.92 (0.79, 1.06) |
| 5–9 | 963 | 123 | 0.90 (0.75, 1.06) | 0.89 (0.75, 1.06) | 0.89 (0.75, 1.06) |
| ≥10 | 1337 | 156 | 0.81 (0.69, 0.94) | 0.86 (0.74, 1.00) | 0.87 (0.75, 1.01) |
| Duration (years)d | |||||
| <10 | 1726 | 236 | 0.91 (0.80, 1.03) | 0.92 (0.81, 1.04) | 0.91 (0.80, 1.03) |
| ≥10 | 577 | 78 | 0.82 (0.65, 1.02) | 0.83 (0.66, 1.04) | 0.86 (0.69, 1.08) |
| Intensity and durationd | |||||
| <10 cigarettes/day, <10 years | 1270 | 175 | 0.92 (0.80, 1.07) | 0.93 (0.80, 1.07) | 0.90 (0.78, 1.04) |
| ≥10 cigarettes/day, <10 years | 456 | 61 | 0.87 (0.68, 1.11) | 0.89 (0.70, 1.12) | 0.95 (0.75, 1.19) |
| <10 cigarettes/day, ≥10 years | 241 | 40 | 0.98 (0.72, 1.34) | 1.02 (0.75, 1.39) | 1.06 (0.78, 1.44) |
| ≥10 cigarettes/day, ≥10 years | 336 | 38 | 0.70 (0.51, 0.95) | 0.69 (0.51, 0.94) | 0.72 (0.53, 0.98) |
| Current regular smokers | |||||
| Intensity (cigarettes/day) | |||||
| <5 | 261 | 35 | 0.93 (0.68, 1.27) | 1.04 (0.78, 1.40) | 1.10 (0.82, 1.47) |
| 5–9 | 488 | 53 | 0.75 (0.57, 1.00) | 0.85 (0.64, 1.12) | 0.84 (0.63, 1.10) |
| ≥10 | 654 | 65 | 0.79 (0.62, 1.01) | 0.81 (0.63, 1.04) | 0.87 (0.68, 1.12) |
| Duration (years)d | |||||
| <10 | 230 | 30 | 0.93 (0.65, 1.32) | 1.08 (0.77, 1.52) | 1.04 (0.74, 1.45) |
| ≥10 | 674 | 69 | 0.74 (0.58, 0.94) | 0.76 (0.60, 0.97) | 0.81 (0.64, 1.03) |
| Intensity and durationd | |||||
| <10 cigarettes/day, <10 years | 157 | 23 | 0.98 (0.59, 0.92) | 1.11 (0.74, 1.64) | 1.12 (0.78, 1.61) |
| ≥10 cigarettes/day, <10 years | 73 | 7 | 0.77 (0.35, 1.73) | 0.96 (0.45, 2.06) | 0.79 (0.38, 1.66) |
| <10 cigarettes/day, ≥10 years | 295 | 38 | 0.82 (0.58, 1.17) | 0.91 (0.65, 1.28) | 0.91 (0.65, 1.26) |
| ≥10 cigarettes/day, ≥10 years | 379 | 31 | 0.66 (0.47, 0.94) | 0.64 (0.45, 0.92) | 0.77 (0.53, 1.10) |
aAdjusted for age, race/ethnicity, education and annual household income.
bAdditionally adjusted for BMI, sugar-sweetened beverage intake, Healthy Eating Index score, multivitamin or folic acid supplement use, sleep duration, PSS-10 score, MDI score, parity, intercourse frequency and doing something to improve chances of conception.
cAdjusted models are also weighted for censoring.
dRestricted to women age 25–34 years.
FR = fecundability ratio.