March 28 (UPI) -- More evidence continues to come in showing potentially harmful effects that smoking during pregnancy can have on babies.

Pregnant women who smoke cigarettes may be raising the risk of their newborn having sudden infant death syndrome, or SIDS, or heart arrhythmia, according to a study that will appear in the April issue of Hearth Rhythm.


The researchers associated fetal nicotine exposure to ongoing disruption of the cardiac sodium current, which helps newborns wake up when they're suffocating during sleep. They observed these results in an experiment with lab rabbits.

"Clinicians often prescribe nicotine replacement therapies to pregnant women who wish to quit smoking in order to reduce the number of crib deaths," lead investigator Robert Dumaine, a researcher at University of Sherbrooke study lead investigator, said in a news release. "However, our data show that nicotine alone is sufficient to alter electrical currents within the heart and generate arrhythmias leading to crib death."

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This disturbance could ultimately keep a newborn from awakening from sleep apnea.

About 85 percent of SIDS cases are caused by utero exposure to tobacco smoke, making it the highest risk factor for the disease.

SIDS is the leading cause of death within a year of life, causing approximately 3,500 deaths each year, according to the Centers for Disease Control and Prevention.

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Another study says smoking during pregnancy may double the risk of a newborn having SIDS.

"The importance of this study is that, for the first time, we provide direct evidence that in utero exposure to nicotine has postnatal effects on the development of the heart and its response to adrenalin and may provide a basis to explain why some babies do not wake up during sleep apnea," Dumaine said. "Therefore, it might be worthwhile to revisit the clinical practice of prescribing the nicotine patch and other NRTs to pregnant women."