Though no one really knows what causes sudden infant death syndrome, or SIDS -- the unexplained death of an infant younger than 1 year -- there are a number of things you can do to reduce your baby's risk:
• Always place baby to sleep on her back, both during naps and at night. Until recently, we thought that side-sleeping was a reasonable alternative to back-sleeping, but now we know it is not. We have a number of studies showing that the side-sleeping position is unstable and increases a baby's chance of rolling onto his stomach. In fact, one study found that the risk of SIDS for side-sleeping babies is similar to the risk for stomach-sleepers. Also, be sure that all caregivers, grandparents, etc., know that your baby must sleep on her back.
• Share your room -- but not your bed -- with baby. There is growing evidence that having your baby's crib or bassinet in your room for the first 6 months reduces the risk of SIDS. When babies are in the same room as a parent, they don't fall into as deep a sleep as they do when they're alone in the nursery. Babies stir at the noises the parents make, and these frequent awakenings are protective. It's fine to breastfeed or hold your baby in your bed, but you should return your baby to his bassinet or crib when you're ready to go back to sleep. As for bed-sharing, doctors discourage the practice. We use soft mattresses and typically lots of pillows and bedding in this country, and a baby in a parents' bed is at risk for suffocation, overheating, strangulation, entrapment, and falls.
• Don't overdress your baby. Some researchers believe that a baby who is too warm falls into such a deep sleep that it is difficult for him to awaken if he is in trouble. A bodysuit and a blanket sleeper are generally sufficient.
• Breastfeed. Babies who are breastfed are more easily roused from sleep than formula-fed babies, which may be a reason breastfed babies are less likely to die from SIDS. Mothers who breastfeed are also less likely to smoke, and a baby's exposure to smoke -- both in the womb and secondhand -- increases the risk for SIDS.
• Give your baby a pacifier. Using a pacifier lowers the risk of SIDS by about two-thirds. We don't know why yet, but it may be that sucking on a pacifier brings a baby's tongue forward, which opens the airway a little bit more. Or it could be that babies who use pacifiers don't fall into as deep a sleep as babies who don't. By the way, you needn't reinsert the pacifier if it falls out of your baby's mouth; while the reasoning is unclear, just putting your baby to bed with the pacifier seems to offer protection. If you're nursing, wait until breastfeeding is well established, around 4 to 6 weeks. --Dana Sullivan
Originally published in American Baby magazine, February 2006. Updated 2009