Pregnant smokers changing their babies’ DNA

As if you need further proof that smoking while expecting can harm your baby – taking a puff while pregnant can change your baby’s DNA.

An international study of more than 6000 women and their children has found more evidence to suggest women who smoke while pregnant can alter the genes of their developing foetus.

Researchers identified 6073 places where the DNA was chemically modified differently – known as DNA methylation – in the children of regular smokers than in the newborns of non-smoking mothers.

The DNA changes were documented in samples of umbilical cord blood drawn after birth. Of the 6685 babies in the analysis, 13 per cent were born to mothers who smoked regularly while pregnant – leaving a lasting mark on the genome that leads into childhood.

Another 25 per cent had mothers who smoked occasionally while pregnant or had quit early in pregnancy.


A separate analysis found that some DNA modifications remained in hundreds of older children (those with an average age of six) whose mothers had smoked while pregnant.

The report was published today in the American Journal of Human Genetics.

The study’s lead author Dr Bonnie Joubert says many signals tied to developmental pathways and the changes were seen in genes relating to lung and nervous system development, smoking-related cancers and birth defects including a cleft lip or palate.

Despite warnings that chemicals from cigarette smoke can be passed through the mother’s placenta, more than 11 per cent of Australian women continue to smoke while pregnant. Smoking while pregnant can lead to miscarriage, a low birth weight, SIDS and reduced lung function.

According to Dr Christopher Gregg, an assistant professor of neurobiology and anatomy and human genetics at the University of Utah, the study’s size helps “to more effectively rule out potentially confounding factors, such as maternal age and socio-economic status” and it had “high impact”.

“It is well established that pregnant women should not smoke, but these new results reveal that smoking during pregnancy leaves a lasting mark on the genome that persists into childhood, and identifies the sites and genes in the genome that are especially susceptible to these effects,” he tells the ABC.

The large study has consolidated previous evidence of a link between smoking and changes in DNA.

(via ABC)

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