It has long been hypothesized by some researchers that exposure to tobacco smoke may have some type of lasting generational effect, where damaging chemicals are passed on from mother to child during gestation. This concern hinges upon evidence suggesting that secondhand smoke in particular persists in a person's bloodstream for several days after she smokes – and in the case of a woman looking to get pregnant, perhaps even long after she has already quit smoking in preparation for an upcoming birth.
These latest tests on pregnant rats appear to affirm this hypothesis, showing that the various chemical components of tobacco smoke directly affect fetal brain development throughout pregnancy. Rats given implanted doses of tobacco smoke extract both before mating and during early and late gestation all showed the same adverse effects, which researchers described as neuro-developmental delays in the brain spanning not only from intra-womb development into early adolescence, but also later on into adulthood.
After administering injectable doses of tobacco smoke extract equivalent to what a pregnant mother might encounter from standard cigarettes, the research team observed adverse effects at nearly all stages of brain development – even when tobacco chemicals were not being breathed in through the lungs, which has the potential to cause even more damage.
"Our study clearly shows there is no stage in which tobacco smoke is innocuous to the developing fetus," explains Theodore A. Slotkin, Ph.D., a professor in Duke's Department of Pharmacology & Cancer Biology, about the implications of what his team discovered through their research.
"We warn women about smoking during pregnancy, and most people are aware that secondhand smoke exposure is also harmful to the fetus, but our study is the first to show that exposure prior to conception is potentially damaging, as well. The public health implications should be obvious."
If nicotine is a major part of the problem, then even e-cigarettes may be a hazard
Where tobacco smoke seems to cause the most damage is in two primary places of the brain: the cholinergic circuits and the serotonin circuits. The former govern learning and memory, while the latter affect mood and emotional behavior. This suggests that the negative effects of tobacco smoke run the gamut of overall brain function.
How it does this is subject matter for future research, but scientists believe that potential causes include the way nicotine and other tobacco chemicals affect a pregnant mother's metabolism and hormonal status. There are even epigenetic implications involving alterations to her eggs, which would suggest that the genes controlling brain function might be expressing themselves differently in mothers who smoke.
"This finding has important implications for public health, because it reinforces the need to avoid secondhand smoke exposure not only during pregnancy, but also in the period prior to conception, or generally for women of childbearing age," Slotkin adds.
The findings build upon earlier ones which affirmed the detrimental effects of nicotine specifically, which implicates not only cigarettes but potentially even e-cigarettes, which many people believe to be safer than standard rolls. All the more reason to avoid tobacco entirely, or to use a high-quality air purifier to keep the air around you clean at all times.
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