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Link between smoking, SIDS studied
Health advice
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It has been known for some time that babies exposed to cigarette smoke in the womb have a higher risk of miscarriage, pre-mature birth and sudden infant death syndrome — a disorder in which seemingly healthy infants inexplicably die. A new study appearing June 3 in The Journal of Neuroscience reports that exposure to cigarette smoke in the womb may dampen a baby’s fight-or-flight responses, leaving the newborn vulnerable to SIDS.
Researchers studied chromaffin cells, which are in the adrenal gland of both rats and humans. In alarming situations — like when a baby is, for any number of reasons, not getting enough oxygen — these cells flood the body with chemical signals called catecholamines. These signals stimulate the fight-or-flight response. Among other responses, catecholamines are very important alarm mechanisms that wake a baby up.
The study showed that chromaffin cells of newborn rats that were exposed to nicotine while in their mothers’ womb produced an increased amount of a protein that actually dampened the chromaffin cells’ responses. This protein,  called potassium ATP channel, acts as a brake by preventing the cells from releasing the fight-or-flight signals in non-threatening situations. Rats that had been exposed to nicotine, had too much potassium ATP which prevented their cells from sounding the alarm and releasing catecholamines when the researchers deprived the rats of oxygen.
This explains why fetuses exposed to cigarette smoke during development end up having a higher risk of SIDS. When pregnant women smoke, nicotine is getting to the fetus at a time when the nervous system is developing. When these systems are disturbed during the developmental processes, infants can’t respond appropriately after they are born.
Exposure to second hand smoke after birth only compounds these negative effects. Almost 20 percent of deaths due to SIDS are linked to a baby being exposed to second-hand smoke in the first year of life.
The sudden and unexplained death of a seemingly healthy baby is a common and very real fear for new parents. It is the leading cause of death for infants between 1 month and 1 year and kills more than 2,500 children annually in the United States.
Sudden infant death syndrome rarely occurs before 1 month of age or after 6 months. Although the exact cause of SIDS is still unknown, researchers have discovered some factors that may put babies at risk. They’ve also identified simple measures you can take to help protect your child from SIDS. Perhaps the most important is placing your baby to sleep on his or her back and keeping tobacco out of his environment.
Researchers will continue to study the affect tobacco has on the baby’s fight-or-flight responses. One fact that is known is that childhood immunizations don’t play a role in SIDS. After reviewing the available evidence in 2005, the American Academy of Pediatrics concluded that vaccines do not increase the risk.
Although SIDS can strike any infant, researchers have identified several factors that may increase a baby’s risk.  They are:
• Male. Boy babies are more likely to die of SIDS than girls.
• Between 1 and 6 months of age. Infants are most vulnerable in the second and third months of life.
• Premature or of low birth weight.
• Black or American-Indian. For reasons that aren’t well understood, race appears to play a role in SIDS.
• Babies placed to sleep on their stomachs. Babies who sleep on their stomachs are much more likely to die of SIDS than are babies who sleep on their backs.
• Born in the fall or winter months. More SIDS cases occur when the weather is cooler.
• Born to mothers who smoke or use drugs.

Ratcliffe is an information specialist with the Coastal Health District. Call her at 876-2173, ext. 236.
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