Sudden Infant Death Syndrome (SIDS)

Definition

One of the most devastating tragedies that can befall young parents is the sudden death of their infant. Although such a death can occur from natural or accidental causes, more than half of such deaths that are unexpected and unexplained are called Sudden Infant Death Syndrome (SIDS). SIDS is the leading cause of death in infants between the ages of one and 12 months in the U.S. and has an incidence of 1-2/1000 live births or 5,000 to 6,000 deaths per year.

Description

The peak age for SIDS is two four months, and it most often occurs during sleep. Although there are more cases during the winter months, SIDS can occur any time of year. Certain groups of infants are at a somewhat higher risk, including premature infants, siblings of SIDS victims (especially where there are two or more SIDS victims in a family) and infants born to substance-abusing mothers. There are currently no diagnostic tests to identify individual infants at risk.

There is often little or no warning for the shocked parents, with less than 10 percent of SIDS victims having had a history of apparent life threatening events (ALTEs). ALTEs are characterized by some combination of apnea (cessation of breathing), color change (usually pale or blue/gray), and choking or gagging, and are understandably frightening to the observer, who may fear that the infant has died. Previous terms to describe these incidents as "aborted crib death" or "near death" wrongly imply a close association between ALTEs and SIDS. In fact, most infants with an ALTE do not subsequently have SIDS.

Prevention

New evidence suggests that a subtle form of suffocation may be the true culprit in one-quarter to one-half of all suspected SIDS cases. There is a growing suspicion among doctors that the position in which babies sleep (face down) may have played a major role in their death.

With the help of the Consumer Product Safety Commission, Dr. James Kemp and Dr. Bradley Thach of the Washington University School of Medicine, obtained information about 25 infants who died face down. All of the babies had been sleeping on soft cushions filled with polystyrene beads which had been intended for infants. The two colleagues began their investigation with a simple test. Each held one of the suspect pillows to his own face and tried to breathe through it. "If you breathe into it for a minute or two, you are okay," says Kemp, an expert in the physiology of infant airways. "But after that you really feel out of breath and uncomfortable."

Even though the cushion had not prevented them from breathing, the air they exhaled had become trapped in the beads, so when they inhaled, they drew in stale air that was low in oxygen. "You end up breathing back in what you've just breathed out," Thach explains. "All the oxygen is used up." Adults have enough lungpower to suck in sufficient oxygen through the pillow, but Kemp and Thach determined that babies could not. By testing rabbits that had the same lung size as infants, the pediatricians proved that rebreathing into the bead-filled cushions was fatal for babies. The two investigators also determined that any movement by the children to free themselves only buried their faces deeper into the pillows.

Risks

Babies seem to be at above-SIDS risk where the following conditions are present:

• in winter time

• if their mothers smoke cigarettes during and/or after pregnancy

• if their mothers are drug addicts

• if their mothers received insufficient health care while pregnant (poor uterine environment)

• if parts of the baby's brain that regulate breathing remain immature (delayed development) - perhaps due to short bouts of oxygen shortage

• if infants are overheated (faulty body temperature control) - Over-swaddling or heavy bedding may make the body work too hard to keep down body temperature.

• if babies are overweight at birth, slow to gain weight or premature - especially with lung disorders

• if they have had serious apnea (temporary breathing stoppage). Several "blue spells" may signal a flaw in breathing control.

• if bottle-fed rather than breastfed

Infant Sleeping Position: "Back to Sleep"

Recent evidence, given much media attention, suggests that some crib deaths may be related to sleeping prone or face down on the stomach. Several studies, particularly those from Australia and New Zealand, have linked the prone position to elevated SIDS risk. Based on the careful evaluation of numerous studies, health officials now want to change the way American babies sleep in the hope of preventing SIDS. Traditionally, American parents have placed their babies on their stomachs to sleep. There is now hope to reverse this practice and to have nearly all babies sleeping on their back and side.

The campaign to educate parents about the importance of sleep position for babies is called "Back to Sleep" and is supported and endorsed by the Surgeon General's Office, the U.S. Consumer Product Safety Commission and the American Academy of Pediatrics.

The specific advice is to let the baby fuss on his or her back (for no more than a few minutes) during the first few months of life before calming him down and trying again. If you try for 20 to 30 minutes three nights in a row and the baby still will not go to sleep on his back, let him fall asleep on the stomach and then turn him onto his back or wait a few days and try positioning him again.

It is not clear why sleeping on the stomach might increase SIDS risk. Possibly, the baby's face and nose become obstructed and hinder breathing or reduce thermo (heat) regulation.

Precautions to reduce the chance of SIDS

• Have good medical care and adequate nutrition during pregnancy.

• Keep baby in smoke-free surroundings (smoking by either parent as well as secondhand smoke are clearly linked with SIDS).

• Put baby to sleep on a firm mattress.

• Breastfeed if possible.

• If "blue spells" are noticed in the infant, get prompt medical advice.

• Try not to let the baby to get too hot (don't over-swaddle).

• Never have the infant's face covered by bedclothes.

• Avoid thick blankets, pillows or bumpers in the crib.

• Try not to let the infant sleep on its stomach.

• Put the baby to sleep on its side or back. (A rolled-up towel along its back will help to keep the baby on its side.)

Questions to Ask Your Doctor

How great is the risk of SIDS in subsequent births?

What can be done next time to prevent it?

Are there any signs or symptoms we should have been aware of?

Would the use of a home monitor diminish the risk?