While SIDS is still not understood fully, several factors can increase a baby's risk of dying from SIDS. They include:

• Infants with low birth weight.
• Premature infants.
• Sex of the baby. Boys are more susceptible to SIDS.
• Age of baby. Babies are most vulnerable to SIDS when they are 1-6 months old, with vulnerability peaking at 2-3 months of age.
• Race of baby. African America, American Indian or Native Alaskan babies are at greater risk for SIDS.
• Babies who sleep on their stomachs are at much higher risk to die from SIDS than are babies who sleep on their backs.
• Babies who are used to sleeping on their backs and suddenly switch to sleeping on their stomachs are at a much higher risk.
• Exposure to secondhand smoke.
• Season of birth. SIDS increases during cooler weather.
• Overheating. Risk of SIDS increases when babies get overheated because they are overdressed, covered with multiple blankets or their rooms are too warm.
• Recent respiratory infections. Commonly, autopsies reveal evidence of a respiratory infection within four weeks of death.
• Siblings of a baby who died of SIDS. Though the risk increase is likely small, some genetic disorders may be involved.
• Mothers who have:
  • Inadequate prenatal care
  • Placental abnormalities
  • Low weight gain during pregnancy
  • First pregnancy when they were younger than 20 years of age
  • Anemia
  • History of sexually transmitted diseases or urinary tract infections
  • History of drug use or smoking during or after pregnancy