Studies revealed that smoking during pregnancy can lead to epigenetic modifications in the fetus which could result to birth defects and other health problems. Published in Environmental Health Perspectives, the study of Christina Markunas and her colleagues from the National Institute of Environmental Health Sciences discovered that newborn babies of mothers who smoked during pregnancy are more likely to experience changes to their DNA compared to those newborns of non-smoking mothers.
Children who are exposed to cigarette smoke while in the womb are at a higher risk of birth defects and more likely to suffer from different health conditions than children of women who never smoked. This difference between children born of smoking and non-smoking mothers remains until adulthood. While scientists are still debating on the real cause, previous studies suggested that exposure to dangerous compounds found in cigarette smoke could result to the changes in the DNA of the growing fetus. Tobacco smoke contains at least hundreds of harmful compounds, 69 of which are known carcinogens.
In a 2011 study, researchers examined the DNA methylation or the adding of a methyl code to a gene as a result of cigarette smoke exposure. Changes in the DNA methylation can alter how a gene functions and heightens the possibility of developing particular diseases, including cancers. The study, which tested the DNA collected from 173 offspring and their mothers, revealed that children born of mothers who smoked while pregnant were two times more at risk of experiencing DNA methylation of a specific gene involved in immune functions and many kinds of cancer than those children with mothers who never smoked during pregnancy.
A much bigger group of children and their mothers were examined by Markunas and her colleagues. They evaluated blood specimens from 889 newborns, where 287 had mothers who smoked during the first trimester of their pregnancy. They have discovered a connection between pregnancy smoking and the unusual methylation in 110 gene sections.
Several of the genes affected have a link in embryonic and placental development, nicotine addiction (and their capacity to quit smoking), and substance abuse. Aside from low birth weight, babies born of women who are smokers are more likely to be drug or nicotine dependents as adults compared to babies who were not exposed to cigarette smoke while in the womb.
However, further studies are required to determine whether these changes in the DNA continue throughout the lifetime.