Risk factors

Although sudden infant death syndrome can strike any infant, researchers have identified several factors that might increase a baby's risk. They include:

• Sex. Boys are slightly more likely to die of SIDS.
• Age. Infants are most vulnerable between the second and fourth months of life.
• Race. For reasons that aren't well-understood, nonwhite infants are more likely to develop SIDS.
• Family history. Babies who've had siblings or cousins die of SIDS are at higher risk of SIDS.
• Secondhand smoke. Babies who live with smokers have a higher risk of SIDS.
• Being premature. Both being born early and having a low birth weight increase your baby's chances of SIDS.

Maternal risk factors

During pregnancy, the mother also affects her baby's risk of SIDS, especially if she:

• Is younger than 20
• Smokes cigarettes
• Uses drugs or alcohol
• Has inadequate prenatal care