Scientists at Otago University have discovered that smoking during pregnancy damages DNA in the placenta.
They found women who smoked had severely damaged DNA in the cells that transfer nutrients and hormones from the placenta to the baby. The mechanisms which normally repair damaged DNA were also affected.
It has long been known that women who smoke are more likely to have children with lower birth weights and a higher risk of serious complications.
The researchers says women who quit smoking at least four weeks before giving birth had less damage. Their next step will be to investigate whether smoking also damages DNA inside the cells of unborn babies.
