Smoking throughout pregnancy appears to have lasting effects on the brain development of the offspring, suggests a study of children aged 9 to 11 years published today in JAMA Network Open. Specifically, the study found that continued exposure to maternal tobacco use in utero was associated with lower brain volume.
“[I]nterventions targeting maternal smoking cessation before pregnancy or in early pregnancy may favor normal brain development among children in the long term,” wrote Runyu Zou, Ph.D., of Erasmus University Medical Center Rotterdam and colleagues.
The researchers analyzed data collected as part of the Generation R Study—a prospective population-based study in Rotterdam, the Netherlands, of 9,778 women who gave birth between April 2002 and the end of January 2006. They focused on the MRI data from 2,704 children (average age, 10 years) and the information on tobacco use during pregnancy provided by children’s parents. Mothers were asked about their tobacco use at the time of study enrollment as well as in each trimester; fathers were asked about their tobacco use at the time of study enrollment only. The researchers categorized maternal tobacco use during pregnancy into one of three categories: never during pregnancy, until the pregnancy was known, and continued during pregnancy.
Of the 2,704 mothers in the study, 77.7% never smoked during pregnancy, 13.5% continued smoking throughout pregnancy, and 8.8% stopped smoking after becoming aware they were pregnant (mostly in the first trimester). Children born to mothers who continued smoking during pregnancy showed lower total brain volume as well as lower cerebral gray matter and white matter volume compared with children born to mothers who never smoked during pregnancy, Zou and colleagues wrote. The children exposed to maternal smoking throughout pregnancy also had smaller surface area and less gyrification (the folding of the cortex) compared with the unexposed children. The brain differences seen in children exposed to maternal smoking throughout the pregnancy were not seen in the children born to mothers who stopped smoking early in pregnancy.
“These associations were not explained by paternal smoking nor mediated by smoking-associated DNA methylation patterns at birth,” the authors reported.
“All efforts should be made to help pregnant women quit smoking as well as to stop the use of all other nicotine-containing products before pregnancy or as early as possible during pregnancy,” Mikael O. Ekblad, M.D., Ph.D., of the University of Turku in Finland wrote in an accompanying editorial. “The goal should not only be smoke-free but also nicotine-free pregnancy … .”
For related information, see the American Journal of Psychiatry article “Nicotine Use and DSM-IV Nicotine Dependence in the United States, 2001–2002 and 2012–2013.”
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