SIDS, or crib death, is the leading cause of death in the first year of life. In utero exposure to tobacco smoke remains the highest risk factor in 85 percent of cases. It therefore seems logical to prescribe nicotine replacement therapies (NRTs) to pregnant women who wish to quit smoking. Tobacco smoke contains over 3,000 toxic compounds identified so far, but out of all the toxic compounds found in smoke, only nicotine is associated with cardiac arrhythmias in newborns.
"Clinicians often prescribe NRTs to pregnant women who wish to quit smoking in order to reduce the number of crib deaths," explained lead investigator Robert Dumaine, PhD, Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada. "However, our data show that nicotine alone is sufficient to alter electrical currents within the heart and generate arrhythmias leading to crib death."
Womb - Fetus - Heart - Reduction - Oxygen
In the womb, the fetus cannot breathe on its own and its heart reacts to a reduction in oxygen by slowing the beating rate and its metabolism to preserve energy. This fetal adaptation is known as "diver reflex." On the other hand, when an infant suffocates during sleep, the brain senses the reduction of oxygen in the blood and will trigger secretion of adrenalin (epinephrine) to accelerate heart rhythm. Once cardiac rhythm accelerates, in part due to increased excitability (sodium current) in the heart, the baby wakes up. This "resuscitation reflex" seems to be absent in babies with SIDS. Instead, those infants display a slowing of heart rate when lacking oxygen, as if their postnatal cardiac development had...
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