There are 6,073 places where the DNA of a fetus can be altered by a mother’s smoking while pregnant. The most complete and ambitious study of the relationship between smoking during pregnancy and changes in fetal DNA that could be precursors to disease was conducted by Stephanie London, an epidemiologist and physician at the National Institute of Environmental Health Sciences, part of the National Institutes of Health. The new evidence that smoking during pregnancy changes fetal DNA like smoking does in adults was reported in the March 31, 2016, edition of the American Journal of Human Genetics.
The researchers analyzed the effects of smoking on fetal DNA through examination of the placental and umbilical blood of 6,685 newborns and their mothers from around the world. The group was segregated into three different categories. Women that smoke throughout their pregnancy, women that did not smoke, and women that smoked some during their pregnancy or gave smoking up early in their pregnancy were examined for genetic alterations caused by DNA methylation from smoking. Methylation is known to alter the DNA of adult smokers.
The fetus is exposed to the majority of chemicals in tobacco smoke through the mother’s blood. The study found that a number of known and previously unknown disease states were the result of smoking while pregnant. The changes in DNA were most often seen in single genes. Smoking has previously been connected to the development of cleft lip and palate. The study found that smoking while pregnant increase the chances for DNA changes that influence lung and nervous system development and increase the potential for a child to develop lung cancer even if the child never smokes.