Expectant mothers should avoid nicotine, even nicotine chewing gum, as it raises the risk of cot death, a new study shows, suggesting that it is not enough for pregnant women to give up smoking.
Scientists have long known that babies of smoking mothers have a much higher risk of cot death than infants of non-smokers, but a Swedish-French study is the first to point to nicotine rather than smoking as the culprit.
"What we have found is that it's the nicotine itself that is dangerous.
"It doesn't matter if you're using nicotine chewing gum - it's just as bad," Dr Hugo Lagercrantz, a professor and paediatrician at the Karolinska Institute who initiated and performed the study, said yesterday.
Many women smokers, and their doctors, have assumed that chewing nicotine gum was safe during pregnancy as a substitute for cigarettes, Dr Lagercrantz said.
In cot death - also known as Sudden Infant Death Syndrome - apparently healthy babies, usually two to four months old, die in their sleep when breathing suddenly stops.
Normally receptors in the brain send an alarm to the nervous system when oxygen levels get too low during sleep - for instance if your nose is blocked or you are sleeping face down.
The message brings you back to consciousness, allowing you to open your mouth or turn over on your back.
Nicotine disturbs this ability to regulate breathing during sleep, the research team found.
The study found genetically modified mice that lack the "wake-up" receptor did not awake although breathing had stopped.
This receptor is also the one that responds to nicotine, so the scientists concluded that in growing foetuses these vital receptors become numb if exposed to nicotine, disturbing the wake-up reflexes and increasing the risk of cot death. - (Reuters)