Smoking During Pregnancy Seems to Alter Fetal DNA, study shows

A new study reveals another reason why pregnant women should not smoke.

The study shows that smoking can alter the baby’s DNA as well as compromise the baby’s growth and development. Mothers who smoke while pregnant may expose their children to a lifetime of chronic conditions and physical deformation.

Researchers analyzed the DNA of more than 6,000 mothers across the world, as well as their newborn children.

Thirteen per cent of mothers in the study reported smoking daily throughout most of their pregnancy.

The results showed that children of the women who smoked while pregnant had DNA modified in ways that could affect the functioning as genes.

Nearly half of those genes play a role in lung and nervous system development, smoking-related cancers and birth defects – including cleft lip and palate.

Those who smoked cigarettes daily throughout most of pregnancy were labeled as ‘sustained smokers.’

Meanwhile, nearly 62 per cent of the women were labeled ‘non-smokers’ and 25 per cent reported occasionally smoking or having quit smoking early on in their pregnancy.

The team analyzed methylation in the newborns’ DNA through samples primarily from blood in the umbilical cord after delivery.

Scientists identified more than 6,000 genetic locations where DNA different from that of newborns whose mothers didn’t smoke.

The scientists found that the collection of genes was largely tied to development pathways.

Another analysis showed that many of the DNA alterations remained in older children whose mothers had smoked during pregnancy.
The scientists found that maternal smoking had an ‘epigenetic’ effect on fetal DNA.

That effect is a chemical influence that does not change the genetic code – but instead determines whether a gene is switched off.

Senior study author Dr Stephanie London said: ‘I find it kind of amazing when we see these epigenetic signals in newborns, from in-utero (in the womb) exposure, lighting up the same genes as an adult’s own cigarette smoking. There’s a lot of overlap.

‘This is a blood-borne exposure to smoking – the fetus isn’t breathing it, but many of the same things are going to be passing through the placenta.’

The team of scientists plans to investigate in further detail how the DNA modifications could influence child development and disease.

Dr London added: ‘We already knew that smoking is related to cleft lip and palate, but we don’t know why.’

Agencies/Canadajournal