Table 6.
Risk of Acute Myeloid Leukemia Associated With Number of Cigarettes Smoked per Day by the Mother and Father, by Period of Exposure, Childhood Leukemia International Consortium, 1974–2012
| Window of Exposure and Smoking Status | No. of Studies | Controls, no. | Cases, no. | ORa | 95% CI |
|---|---|---|---|---|---|
| Mother | |||||
| Prenatal | 11 | ||||
| Nonsmokers | 6,037 | 512 | 1.00 | Referent | |
| Moderate smokersb | 2,074 | 130 | 0.82 | 0.66, 1.00 | |
| Heavy smokersc | 4,321 | 404 | 0.74 | 0.50, 1.11 | |
| Per 5 cigarettes/dayd | 12,432 | 1,046 | 0.99 | 0.98, 1.00 | |
| Preconception | 6 | ||||
| Nonsmokers | 5,569 | 461 | 1.00 | Referent | |
| Moderate smokersb | 1,576 | 99 | 0.82 | 0.65, 1.04 | |
| Heavy smokersc | 854 | 54 | 0.83 | 0.61, 1.13 | |
| Per 5 cigarettes/dayd | 7,999 | 614 | 0.95 | 0.89, 1.01 | |
| Pregnancy | 9 | ||||
| Nonsmokers | 8,448 | 723 | 1.00 | Referent | |
| Moderate smokersb | 1,812 | 139 | 0.96 | 0.79, 1.17 | |
| Heavy smokersc | 383 | 23 | 0.68 | 0.44, 1.07 | |
| Per 5 cigarettes/dayd | 10,643 | 885 | 0.96 | 0.89, 1.03 | |
| Postnatal | 4 | ||||
| Nonsmokers | 3,544 | 301 | 1.00 | Referent | |
| Moderate smokersb | 570 | 41 | 0.87 | 0.61, 1.23 | |
| Heavy smokersc | 206 | 10 | 0.54 | 0.28, 1.04 | |
| Per 5 cigarettes/dayd | 4,320 | 352 | 0.92 | 0.82, 1.04 | |
| Father | |||||
| Prenatal | 7 | ||||
| Nonsmokers | 5,296 | 375 | 1.00 | Referent | |
| Moderate smokersb | 1,726 | 141 | 1.18 | 0.96, 1.45 | |
| Heavy smokersc | 1,949 | 174 | 1.31 | 1.08, 1.60 | |
| Per 5 cigarettes/dayd | 8,971 | 690 | 1.06 | 1.02, 1.10 | |
| Preconception | 5 | ||||
| Nonsmokers | 3,252 | 254 | 1.00 | Referent | |
| Moderate smokersb | 1,113 | 85 | 1.04 | 0.79, 1.35 | |
| Heavy smokersc | 1,217 | 117 | 1.37 | 1.07, 1.77 | |
| Per 5 cigarettes/dayd | 5,582 | 456 | 1.06 | 1.02, 1.11 | |
| Pregnancy | 3 | ||||
| Nonsmokers | 2,283 | 149 | 1.00 | Referent | |
| Moderate smokersb | 884 | 58 | 1.03 | 0.74, 1.44 | |
| Heavy smokersc | 997 | 89 | 1.41 | 1.06, 1.89 | |
| Per 5 cigarettes/dayd | 4,164 | 296 | 1.06 | 1.01, 1.12 | |
| Postnatal | 3 | ||||
| Nonsmokers | 2,546 | 139 | 1.00 | Referent | |
| Moderate smokersb | 779 | 43 | 0.93 | 0.65, 1.33 | |
| Heavy smokersc | 937 | 68 | 1.27 | 0.93, 1.73 | |
| Per 5 cigarettes/dayd | 4,262 | 250 | 1.03 | 0.97, 1.10 | |
Abbreviations: CI, confidence interval; OR, odds ratio.
a Odds ratios were adjusted for age, sex, ethnicity, highest parental education (using imputed values for mothers when needed), and study center.
b Moderate smokers are defined as smoking 1–15 cigarettes per day.
c Heavy smokers are defined as smoking 16 or more cigarettes per day.
d Odds ratios were computed with the continuous variable provided, divided by 5.