BACKGROUND Maternal smoking in pregnancy is associated with low birth weight (LBW), child conduct problems, hyperactivity and lower cognitive attainment, but associations may reflect measured and unmeasured confounding. Cross-cohort designs can aid causal inference through comparison of associations across populations with different confounding structures. We compared associations between maternal smoking in pregnancy and child conduct and hyperactivity problems, cognition and LBW across two cohorts born four decades apart. METHODS Two national UK cohorts born in 1958 (n = 12 415) and 2000/01 (n = 11 800) were compared. Maternal smoking in pregnancy and child birth weight was assessed at or shortly after birth. Parents rated children's conduct problems and hyperactivity, and children completed standardized tests of reading and mathematics. RESULTS Maternal smoking in pregnancy was less common and more strongly associated with social disadvantage in 2000/01 compared with 1958 (interactions P < 0.001). Maternal smoking in pregnancy was robustly and equivalently associated with infant LBW in both cohorts [interactions: boys odds ratio (OR) = 1.01 (0.89, 1.16), P = 0.838; girls OR = 1.01 (0.91, 1.17), P = 0.633]. Maternal smoking was more strongly associated with conduct problems, hyperactivity and reading in the 2000/01 cohort (interactions P < 0.001). CONCLUSIONS Marked cross-cohort change in associations between maternal smoking and child conduct problems, hyperactivity and reading highlights the likely role of confounding factors. In contrast, association with LBW was unaffected by change in prevalence of maternal smoking and patterns of confounding. The study highlights the utility of cross-cohort designs in helping triangulate conclusions about the role of putative causal risk factors in observational epidemiology.

中文翻译：

---

使用跨队列比较设计测试孕产妇吸烟在怀孕中对儿童心理健康和学习的作用：来自两个相距四十年的英国队列的证据。

背景技术孕期孕妇吸烟与低出生体重（LBW），儿童行为问题，多动症和认知能力低下有关，但这种关联可能反映出可测量和不可测量的混淆。跨队列设计可以通过比较具有不同混杂结构的人群之间的关联来帮助因果推理。我们比较了两个年龄相距四十岁的队列中孕妇吸烟与儿童行为和多动问题，认知和低水平体重之间的关联。方法比较了两个分别于1958年（n = 12 415）和2000/01（n = 11 800）出生的英国国家队列。在出生时或出生后不久评估孕妇的吸烟状况和孩子的出生体重。父母给孩子们的行为和多动症打分，孩子们完成了阅读和数学的标准化测试。结果与1958年相比，在2000/01年度，孕产妇吸烟较少见，并且与社会不利因素关系更密切（相互作用P <0.001）。在两个队列中，孕期孕妇吸烟与婴儿LBW均具有显着相关性[互动：男孩的优势比（OR）= 1.01（0.89，1.16），P = 0.838；女孩OR = 1.01（0.91，1.17），P = 0.633]。在2000/01队列中，母亲吸烟与行为问题，活动过度和阅读密切相关（交互作用P <0.001）。结论产妇吸烟与儿童行为问题，多动症和阅读之间的关联显着跨队列变化突出了混杂因素的可能作用。相反，与低出生体重的相关性不受产妇吸烟率变化和混淆模式的影响。