Using e-cigarettes or nicotine patches during pregnancy could increase the risk of cot death in newborns, an early study has found.
Exposure to nicotine in the womb can affect the central nervous system and cardiorespiratory responses, leaving newborns vulnerable to asphyxia.
"Sudden infant death syndrome is such a distressing tragedy for families," Stella Lee, one of the researchers behind the study at the Geisel school of medicine, said.
"We still don't fully understand the causes, but this research is important because it helps mothers reduce the risk."
It is believed that nicotine exposure can stop autoresuscitation – a crucial safety mechanism that means babies can recover if they are suddenly deprived of oxygen by, for example, getting tangled in bedding or having their breathing obstructed.
This increases the chances of sudden infant death syndrome, or cot death.
Nearly 300 babies in the UK die suddenly and unexpectedly, mostly during the first six months of life.
It is estimated that around 10% of women continue to smoke during pregnancy, and nicotine replacement therapies have become an acceptable replacement, prescribed to women in place of cigarettes.
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The research, which involved exposing unborn rats to nicotine through maternal blood and testing their oxygen response, could bring the approach under question.
"We will continue to identify the possible predictors of risk and consider how we can treat infants who have a compromised autoresuscitation mechanism," Dr Aihua Li, a senior author of the study, said.
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