SIDS - Sudden infant death syndrome.

The reason it is called such is because, well, its sudden, and happens for "no reason" It has no rhyme or reason. Things you can do to "prevent" it: Have baby sleep on their back, No toys or heavy blankets around, they can smother under them.

I don't know how often it happens, just that it does.

SIDS occurred almost exactly 1:2000 live births in the U.S. in 2004, with the rate decreasing every year.

And excellent page with lots of tips is: http://www.sids.org/nprevent.htm

Our winning strategy was very similar to the one doctors suggest-
- He slept on his back until he was old enough to turn over on his stomach on his own (which didn't take long, trust me.)
- His blankets were tucked in to the mattress to basically make a baby envelope. This prevents bunching and gathering near the mouth/around the neck area.
- No pillows until about one year, and even that was risky, but it helped him sleep at night. at first is was used under the baby mattress to provide angle during sick nights, but eventually got moved up above.
- Pacifiers at bedtime to help prevent him from doing truly crazy things like just swallowing his own tongue at random.
- Stuffed animals didn't find their way into the crib until he was strong enough to move them around on his own, about one year.

He's two now and sleeps with his head stuffed inside/under whatever is available, be it a blanket, or stuffed animals in the room, or even wicker baskets used to contain toys, so there are almost daily scares, but he's still strong and healthy and quite prone to living through the night. :)

Most of the major changes occurred after one year, as the likelihood of SIDS decreases dramatically after the first year, though can affect children up to five.