在美国死于癌症的人30％是由于吸烟导致的，然而孕期吸烟与儿童癌症的关系却很少研究。由于儿童癌症发病率很低，因而有关儿童癌症的研究多用病例对照分析。以前仅有三次前瞻性队列研究，第一次发现，母孕期吸烟，儿童患癌症的危险性增加了2．47倍；第二次发现，母孕期吸烟，儿 Thirty percent of people who die of cancer in the United States are caused by smoking, but the relationship between smoking during pregnancy and childhood cancer is rarely studied. Due to the low incidence of childhood cancer, and therefore the use of case-control analysis of childhood cancer. Previously only three prospective cohort studies, for the first time found that during pregnancy, smoking, children increased the risk of cancer 2.47 times; the second found that smoking during pregnancy, children