Paper Title
A dose-response relationship between maternal smoking during late pregnancy and adult intelligence in male offspring
Keywords
- Maternal Smoking
- Pregnancy
- Adult Intelligence
- Male Offspring
- Dose-Response Relationship
- Cognitive Development
- Behavioural Development
- Third Trimester
- Copenhagen Perinatal Cohort
- Military Draft Board Intelligence Test
- Parental Social Status
- Parental Education
- Single Mother Status
- Gestational Age
- Birthweight
- IQ Difference
- Long-Term Consequences
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Publication Info
Volume: 19 | Issue: 1 | Pages: 4-11
Published On
January, 2005
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Abstract
An association between maternal smoking during pregnancy and cognitive and behavioural development has been observed in several studies, but potential effects of maternal smoking on offspring adult intelligence have not been investigated. The objective of the present study was to investigate a potential association between maternal smoking during pregnancy and offspring intelligence in young adulthood. Adult intelligence was assessed at the mean age of 18.7 years by a military draft board intelligence test (Børge Priens Prøve) for 3044 singleton males from the Copenhagen Perinatal Cohort with information regarding maternal smoking during the third trimester coded into five categories (about 50% of the mothers were smokers). The following potential confounders were included as covariates in multivariable analyses: parental social status and education, single mother status, mother's height and age, number of pregnancies, and gestational age. In separate analyses, birthweight and length were also included as covariates. Maternal cigarette smoking during the third trimester, adjusted for the seven covariates, showed a negative association with offspring adult intelligence (P = 0.0001). The mean difference between the no-smoking and the heaviest smoking category amounted to 0.41 standard deviation, corresponding to an IQ difference of 6.2 points [95% confidence interval 0.14, 0.68]. The association remained significant when further adjusted for birthweight and length (P = 0.007). Both unadjusted and adjusted means suggested a dose-response relationship between maternal smoking during pregnancy and offspring adult intelligence. When subjects with missing data were excluded, essentially the same results were obtained in the reduced sample (n = 1829). These results suggest that smoking during pregnancy may have long-term negative consequences on offspring adult intelligence.
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