A new study by researchers with Kaiser Permanente Northern California suggests a simple strategy for reducing the risk of sudden death of infants in their sleep: turning on a fan at night.

The study's findings, based on data collected from nearly 500 mother-and-child pairs in California between 1997 and 2000, indicate that the use of a fan in an infant's room may reduce the likelihood of sudden death by 72%. But the data suggest that the protective effect applies mostly to babies in poor sleeping environments — those who are put to bed in overheated rooms or on their stomach.

The National Institute of Child Health and Human Development (NICHD) issued a statement in response to the study, published Oct. 6 in the Archives of Pediatrics & Adolescent Medicine, warning that "that there is no substitute for the most effective means known to reduce the risk of [sudden infant death syndrome, or] SIDS: always placing infants for sleep on their backs."

The NICHD's federally funded "Back to Sleep" campaign, which advocates for putting babies to sleep face-up, has helped reduce the national SIDS death rate 56%, from 1.2 deaths per 1,000 live births in 1992 to .53 deaths per 1,000 live births in 2003. In addition to placing babies on their backs to sleep, pediatricians recommend that parents use firm mattresses for babies, avoid soft bedding such as comforters and quilts, put babies in their own cribs at night, keep infants from overheating and refrain from smoking during pregnancy and infancy.

Indeed, the study's authors say that caretakers who followed established safety guidelines were less likely overall to suffer the sudden death of a child, compared with those who tended not to take the same precautions. The study also found that when fans were used in the absence of other environmental risk factors — that is, when parents already had other safeguards in place — it had no significant additional impact on the risk of SIDS.

"If the baby was already in a good sleeping environment, there wasn't very much chance they were 'rebreathing,'" says Dr. De-Kun Li of Kaiser Permanente's Division of Research and a co-author of the study, referring to the re-inhalation of carbon dioxide that is associated with sudden unexplained death. "So it's not surprising that adding a fan, or not, didn't make that much difference."

The benefit of a fan became apparent, however, when it was used in sleep environments typically associated with a higher risk of SIDS. For example, researchers found that fans were associated with a 94% reduction in SIDS risk for babies who slept in rooms that exceeded 70 degrees F (21 degrees C); an 85% reduction for infants in rooms with closed windows; an 86% reduction among babies placed on their sides or stomach to sleep; and a 78% reduction among those who did not use a pacifier (the pacifier's handle is hypothesized to help maintain babies' breathing space under a blanket or in soft bedding).

"If you decrease the chance of rebreathing exhaled air, your SIDS rate is going to be reduced, says Li. "Using a fan is one way."

Betty McEntire, executive director of the American SIDS Institute, says the study is useful for underscoring the link between SIDS and rebreathing or overheating. "We know that increased carbon dioxide can hurt the baby's ability to arouse during sleep," says McEntire. "So you definitely want to prevent your baby from rebreathing and overheating."

"Chipping away at the SIDS problem is important," McEntire continues, "and this study adds a little bit [of clarity] to the puzzle."

The etiology of SIDS is still largely a mystery. To date, perhaps the best evidence of its cause comes from a 2006 study led by researchers at Children's Hospital Boston, who examined the brain tissue of babies who died from SIDS and those who died from other causes. Researchers found that SIDS babies often have a brain defect in a region of the brain that controls breathing, heart rate and blood pressure. The abnormality appears to weaken the responsiveness of certain functions, including arousal from sleep when the body fails to get enough oxygen. Researchers think the defect may be genetic in origin, although there are no biological tests yet to determine risk.

For now, the study's authors agree that the best way to reduce the likelihood of SIDS — the leading cause of death among American infants aged under 1 year, which kills more than 2,000 infants each year — is through environmental safety measures put forth by the American Academy of Pediatrics. Using a fan, Li says, "can provide concerned parents an extra measure to reduce SIDS."

北加州凯瑟医疗中心的研究人员最新的发现表明减少婴儿突然死亡的一个简单的办法就是：在孩子晚上睡觉的时候打开风扇。

这项研究搜集了1997年到2000年之间加州的将近500对母子的资料，研究成果表明在婴儿的房间内使用风扇可以减少72%的死亡率。但是数据显示这样的保护措施大多是孩子睡眠环境不好时——像那些房间过热，或者趴着睡的孩子。

国家儿童保健和人类发育研究所针对这个研究发表了一份声明（登在10月6日出版的儿童和青少年医学杂志上），警告说没有机构对现在知道的最有效的减少婴儿猝死的办法——让孩子平躺着睡觉更好的办法了。

国家儿童保健和人类发育研究所在全联邦范围内发起“平躺着睡觉”运动，此运动提倡让孩子面朝上入眠，这已经把全国婴儿猝死率减低了565,从1992年的1，000个人中有1.2人死亡到

2003年底饿1，000人中0.53人死亡。除了让孩子平躺着睡觉之外，儿科医生还推荐父母给孩子用的床垫不要太软，避免像靠垫，被子之类物品，晚上把孩子放到婴儿床上，远离过热的环境，而且在怀孕期间，幼儿期内要远离香烟。

其实，这项研究的主编说看护人只要按照既有的安全向导做事根本不可能使孩子猝死的，这可以和没有预防心里的人做个比较。这项研究同时还发现如果父母在已经有预防措施的房间里使用风扇的话，这种做法对婴儿猝死是没有影响的。

“如果孩子的睡眠环境良好，那就没有必要换气了。”谈到和无法解释的猝死相关的二氧化碳二次吸入时，凯瑟医疗研究分部李德坤医生说到，他也是这个研究的副编。

然而，在典型的造成婴儿猝死的睡眠环境中，风扇的作用显而易见，比如，研究者发现风扇在婴儿睡眠的房间温度超过华氏71度（摄氏21度）是，可以把死亡率减少94%；在关着窗户的屋子里可以减少85%；在趴着睡觉的孩子中可以减少86%，与没有使用奶嘴的手柄的孩子相比可以减少78%（奶瓶被被假设为孩子在毯子下或软床上是的呼吸空间）。

如果减少呼入已经呼出的气体，婴儿猝死率将会得到减少，李说“使用风扇是个办法。”