Back to Sleep: The Best Bedtime Position for Baby

According to the NICHHD, sudden infant death syndrome is technically defined as "the sudden death of an infant under one year of age, which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history."

SIDS is a new parent's worst fear. An apparently healthy baby with no obvious previous or present illness goes to sleep and never wakes up. As the NICHHD definition states, examination of the infant's medical history, home, and even an autopsy do not reveal a cause of death in true SIDS cases.

Infants at increased risk for SIDS are those older than one month but younger than six months, those born prematurely, males, and twins or triplets. African-American babies are at higher risk than babies of European descent, and American Indian or Alaskan Native babies are considerably more so—up to two or three times the national average.

While breathing issues are the start of a SIDS death, recent research suggests that its deadliness comes in combination with a wiring problem in the baby's brain. Certain infants may have a delay in maturation or poor development of a network of brain cells normally responsible for waking or alerting the child when a life-threatening situation (like lack of oxygen) is present. The brain areas involved develop in midgestation.

In 1990, there were 5,417 reported SIDS deaths in the US, according to the National Vital Statistics Reports, National Center for Health Statistics, and in 2004 there were 2,246 such deaths reported, which attests to the efforts to prevent it. (The infant mortality rate from all causes declined in that period as well, it should be noted, and preliminary results for 2006—the most recent figures available—show a further decline.)

The Back to Sleep recommendation is for healthy infants only. Those with upper airway anomalies, gastroesophageal reflux, or other problems may or may not benefit from sleeping on their backs. Parents should discuss these special situations with their child's doctor.