Hook E B, Cross P K
Am J Hum Genet. 1985 Nov;37(6):1216-24.
A matched case-control study of 100 mothers of Down syndrome children, 100 mothers of children with other defects (defect controls), and 100 mothers of children with no defects (normal controls) was carried out. All infants were born in upstate New York in 1980 and 1981. Matching was very close on maternal age for the normal controls but not for the defect controls. The risk ratios for the association of cigarette smoking around the time of conception with Down syndrome was 0.58 (90% confidence interval of 0.34-0.98) in the case-defect control comparison and 0.56 (90% confidence interval of 0.33-0.95) in the case-normal control comparison. Stratification by alcohol ingestion and maternal age did not abolish the negative trend to association. The results are contrary to that of an earlier study of others that found a positive association of older age and trisomy in spontaneous abortions. In fact, among mothers of Down syndrome cases over age 30 in this analysis, the risk ratio was lower than for younger mothers. (For case-normal control comparisons, the value was 0.39 [90% confidence interval of 0.17-0.87]). If not due to chance or confounding, the negative association in our data may be attributable to, among other factors, a selective effect of smoking upon survival or fertilizability of +21 gametes prior to conception or upon survival of +21 conceptuses after fertilization.
对100名唐氏综合征患儿的母亲、100名有其他缺陷患儿的母亲（缺陷对照）和100名无缺陷患儿的母亲（正常对照）进行了一项配对病例对照研究。所有婴儿均于1980年和1981年出生在纽约州北部。正常对照在母亲年龄上匹配得非常接近，但缺陷对照并非如此。在病例-缺陷对照比较中，受孕前后吸烟与唐氏综合征关联的风险比为0.58（90%置信区间为0.34 - 0.98），在病例-正常对照比较中为0.56（90%置信区间为0.33 - 0.95）。按饮酒情况和母亲年龄分层并未消除这种负相关趋势。这些结果与早期其他人的一项研究结果相反，该研究发现自然流产中年龄较大与三体性呈正相关。事实上，在本分析中30岁以上的唐氏综合征病例的母亲中，风险比比年轻母亲更低。（对于病例-正常对照比较，该值为0.39 [90%置信区间为0.17 - 0.87]）。如果不是由于偶然或混杂因素，我们数据中的负相关可能归因于除其他因素外，吸烟对受孕前+21配子的存活或受精能力或受精后+21胚胎的存活的选择性影响。
