Alive and well since 1994, the National Institute of Child Health and Human Development's (NICHD) "Back to Sleep" campaign has been encouraging parents to put their children to sleep on their backs to reduce the risk of SIDS (Sudden Infant Death Syndrome). Additionally, the NICHD and American Academy of Pediatrics (AAP) also advise parents not to share their bed with infants.
While nobody can pinpoint the exact cause of SIDS, Kaiser researchers found:
Infants who slept in rooms ventilated by fans had a 72 percent lower risk of SIDS compared to infants who slept in bedrooms without fans. Using a fan appeared be most effective with infants in high-risk environments, such as those sleeping in overheated rooms or on their stomachs. Researchers hypothesized that fans may improve ventilation and decrease the chance that babies will rebreathe exhaled carbon dioxide (an explanation for SIDS known as the "stale-air hypothesis").
To see what one consultant to the National Institutes on Health has to say about it,
Board member of the American SIDS Institute, Carl Hunt says, "Though the data from the Kaiser study of fans is promising, the link between the use of fans and a decrease in SIDS isn't definitive. . . Reduced breathing of stale air when using a fan … is only speculation at this time. What they've shown is an association, but that doesn't mean that use of the fan causes less risk of SIDS. It may be that families who use fans have a lower risk for SIDS anyway."
I've always had one for white noise, but now I'm thinking it's a positive addition for the baby's well being, too.