Dr Nadja Reissland has researched scans of unborn babies whose mothers smoke and detected tiny differences in their movements from those whose mothers do not smoke The harmful effects of smoking during pregnancy on unborn babies may be seen in tiny movements in their faces using 4-d ultrasound scans, new research has found. Pregnant women have long been urged to give up cigarettes because they heighten the risk of premature birth, respiratory problems and even cot death.