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Smoking in pregnancy alters baby’s DNA, organs: study

Smoking while pregnant causes chemical changes to the DNA of the unborn baby or foetus so much that it may predispose them to lifelong health conditions, said new research sending another shockwave across the world.

Changes in the chemical structure of the baby’s DNA can be detected from as early as 12 weeks into pregnancy, said the research adding significant weight to existing knowledge of the dangers of smoking by pregnant mothers.

Researchers from the Universities of Edinburgh, Aberdeen, Glasgow and Nottingham showed that maternal smoking leads to crucial changes in chemical tags known as ‘epigenetic marks’, which are attached to DNA and known as DNA methylation, which can affect how genes function.

The study also showed that maternal smoking affected normal differences in tissues and organs between the sexes, which are known to be important for good health.

“Our study also detected important sex differences in foetal liver function. We found that exposure to maternal smoking resulted in the livers of male foetuses becoming more like female livers and vice-versa,” said Professor Peter O’Shaughnessy of the University of Glasgow.

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The researchers were able to show for the first time that such changes are present in the livers of unborn children from between 12 and 20 weeks of pregnancy. These changes in DNA methylation may mean the baby is more susceptible to a range of diseases in future.

“From as early as the second trimester, a baby whose mother smokes is at an increased risk of developing obesity, cardiovascular disease, cognitive problems and asthma and this risk lasts throughout life. The liver is a key metabolic target tissue and changes here are likely to have a direct effect on foetal development and long-term health,” said Amanda Drake from the Centre for Cardiovascular Science, University of Edinburgh.

Babies born to smoking mothers are more likely to grow up to be obese and diabetic, they said. It is estimated that the prevalence of smoking during pregnancy still remains high. In developed countries up to 25 per cent of pregnant women smoke and fewer than 4% stop smoking while pregnant.

The research is published in the journal BMC Medicine.

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