MATERNAL SMOKING DURING PREGNANCY AND CHILDHOOD-CANCER

The association between maternal smoking during pregnancy and childhoo d cancer was investigated using prospectively collected data from 54,7 95 liveborn children in the Collaborative Perinatal Project (1959-1966 ). Cases of cancer had a histologic diagnosis and/or a compatible clin ical course. There were 51 children with cancer, for a cumulative inci dence of cancer of 1.1 per 1,000 by 96 months of age. Maternal smoking was determined al each prenatal visit; 52% of mothers reported smokin g at one or more visits. By age 8 years, cancer had occurred in 1.4 pe r 1,000 children whose mothers did not smoke during pregnancy, compare d with 0.9 per 1,000 children whose mothers smoked (p = 0.15 by log ra nk test); the hazard ratio was 0.67 (95% confidence interval (CI) 0.38 -1.17). There was no dose-response effect of smoking compared with non smokers (hazard ratio for one to 10 cigarettes/day = 0.45, more than 1 0 cigarettes/day = 0.83). The hazard ratio for leukemia among children whose mothers smoked was 0.82 (95% CI 0.31-2.11); the hazard ratio fo r cancers other than leukemia was 0.60 (95% CI 0.30-1.20). Adjustment did not change the hazard ratio substantially. Although the relatively small number of cases precluded extensive study of individual types o f cancer, the authors conclude that maternal smoking during pregnancy is not associated with an increased risk of childhood cancer in this c ohort.