How Cigarettes Cause Sudden Infant Death

Scientists have known that exposure to cigarette smoke in the womb ups the odds of sudden infant death syndrome. Now they think they know why.

The smoke messes with a baby's fight-or-flight system, a study of rats suggests.

Since 1983, the rate of SIDS has fallen by over 50 percent, but there are still about 2,500 deaths per year in the United States caused by the mysterious syndrome.

Here is what's supposed to happen if a sleeping baby is not getting enough oxygen or undergoing some other stressful situation: chromaffin cells release adrenaline and other fight-or-flight stimulants, and the baby wakes up.

But in newborn rats exposed to nicotine in the womb, the setup is dampened. Rats are good analogues for humans, but more work will be needed to see if the same thing happens in people.