Smoking while pregnant alters foetal DNA, research shows

Recent research undertaken by UK academics provides new evidence that smoking during pregnancy carries significant health risks for the baby.

Dr Amanda Drake, based at Edinburgh University’s Centre for Cardiovascular Science, along with researchers from the Universities of Aberdeen, Glasgow and Nottingham, have detected chemical changes in the DNA of foetuses as early as 12 weeks.

According to the article published in BMC Medicine, an analysis of the developing liver showed that maternal smoking causes key alterations to the methylation of DNA (chemical tags attached to the DNA).

It also causes changes to the vitamin B12 component, plasma homocysteine, and expression of enzymes in the 1-carbon cycle in foetal liver.

The research builds on the findings of previous studies.

In comments to The Student, Dr Drake said that while “other research groups have described similar changes in babies at birth […] we are showing that these changes are induced in early pregnancy and that they occur in a tissue of interest – the liver has a major role in metabolism for example.”

The research suggests that altered DNA methylation may underlie increased susceptibility to later obesity, cardiovascular disease, cognitive problems and asthma.

Professor Paul Fowler of the University of Aberdeen, who led the Medical Research Council funded project, said: “The burden of maternal smoking persists into adulthood, with these babies more likely to grow up to be obese and diabetic.” Despite previous health warnings of the risks to the unborn baby, it is estimated that of the 25 per cent of women that smoke in developed countries, fewer than four per cent stop smoking while pregnant.

Dr Drake added that the researchers “hope that this research will further highlight to pregnant women the potential dangers to the baby of smoking while pregnant.”

When questioned as to whether the effects extend to mothers who have had regular exposure to cigarette smoke prior to becoming pregnant, Dr Drake said that the current thinking is that “it is the smoke exposure itself rather than any effects smoking has previously had in the mothers that is causing the problems.” However, she cautioned that the research only looked at the period of pregnancy itself, comparing the foetuses of women who smoked alongside those who did not.

This leaves room for further research into contributing risk factors.

She added: “We would still argue that giving up smoking gives the baby the best chance of developing normally.”   The research was funded by the Medical Research Council, Chief Scientist Office Scotland, the European Community’s Seventh Framework Programme and NHS Grampian Endowments.

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