Breslau Naomi, Paneth Nigel, Lucia Victoria C, Paneth-Pollak Rachel
Department of Epidemiology, Michigan State University, College of Human Medicine, East Lansing, MI 48824, USA.
Int J Epidemiol. 2005 Oct;34(5):1047-53. doi: 10.1093/ije/dyi163. Epub 2005 Aug 5.
Maternal smoking in pregnancy lowers birthweight. It is unclear, however, whether smoking during pregnancy lowers offspring IQ, and, if it does, whether it is through the smoking effect on fetal growth.
Representative samples of low birthweight (<2500 g) and normal birthweight children born in 1983-85 from inner-city and suburban communities in southeast Michigan, USA were assessed at ages 6, 11, and 17, using Wechsler intelligence tests. Smoking during pregnancy was ascertained from mothers at the first assessment; and smoking at any time was ascertained at the first and second assessment. Generalized estimating equation models were used, with children's IQ at all three assessments as outcomes (n = 798).
Without adjustment, offspring of mothers who smoked during pregnancy scored 6.8 IQ points lower than offspring of mothers who never smoked, on average. Low birthweight children scored 5.4 IQ points lower than normal birthweight children, on average. The statistical association of maternal smoking with offspring IQ was confounded by maternal characteristics, chiefly, maternal cognitive ability as measured by IQ and education; adjustment for these factors eliminated the association. By contrast, adjustment for maternal IQ and education as well as smoking during pregnancy had a negligible effect on the low birthweight-related IQ deficit. Low birthweight did not mediate the association of smoking and lowered IQ in offspring.
Maternal smoking during pregnancy is a proxy for a matrix of vulnerabilities for adverse child cognitive development and has no direct causal effect on child's IQ. The relationship of low birthweight and IQ is independent of maternal smoking and maternal cognitive abilities.
孕期母亲吸烟会降低出生体重。然而，尚不清楚孕期吸烟是否会降低后代智商，如果会，是否是通过吸烟对胎儿生长的影响。
对1983 - 1985年出生于美国密歇根州东南部市中心和郊区社区的低体重（<2500克）和正常体重儿童的代表性样本，在6岁、11岁和17岁时使用韦氏智力测验进行评估。孕期吸烟情况在首次评估时从母亲处确定；任何时候的吸烟情况在首次和第二次评估时确定。使用广义估计方程模型，将所有三次评估时儿童的智商作为结果（n = 798）。
未经调整时，孕期吸烟母亲的后代平均智商得分比从不吸烟母亲的后代低6.8分。低体重儿童的平均智商得分比正常体重儿童低5.4分。母亲吸烟与后代智商之间的统计关联被母亲特征所混淆，主要是通过智商和教育程度衡量的母亲认知能力；对这些因素进行调整后消除了这种关联。相比之下，对母亲智商、教育程度以及孕期吸烟进行调整，对与低体重相关的智商缺陷影响可忽略不计。低体重并未介导吸烟与后代智商降低之间的关联。
孕期母亲吸烟是儿童不良认知发展一系列易患因素的代表，对儿童智商没有直接因果影响。低体重与智商之间的关系独立于母亲吸烟和母亲认知能力。
