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Neonatal Problems: Sudden Infant Death Syndrome


The National Institute of Child Health and Human Development [ 1 ] defines Sudden Infant Death Syndrome (SIDS) as "the diagnosis given for the sudden death of an infant under 1 year of age that remains unexplained after a complete investigation, which includes an autopsy, examination of the death scene, and review of the symptoms or illnesses the infant had prior to dying and any other pertinent medical history."

SIDS is the leading cause of death in infants between 1 month and 1 year of age, with most SIDS deaths occurring between 1 and 4 months of age. SIDS kills 3 out of every 2,000 infants. African American children are 2 to 3 times more likely than white babies to die of SIDS, and Native American babies are about 3 times more susceptible. Also, more boys are SIDS victims than girls.

Risk Factors

A number of factors seem to put a baby at higher risk of dying from SIDS. These include:

  • Babies who sleep on their stomachs.
  • Mothers who smoke during pregnancy are 3 times more likely to have a SIDS baby.
  • Exposure to passive smoke from smoking by mothers, fathers, and others in the household doubles a baby's risk of SIDS.
  • Mothers who are less than 20 years old at the time of their first pregnancy.
  • Babies born to mothers who had no or late prenatal care.
  • Premature or low birth weight babies.


Mounting evidence suggests that some SIDS babies are born with brain abnormalities that make them vulnerable to sudden death during infancy. Studies of SIDS victims reveal that many SIDS infants have abnormalities in the arcuate nucleus , a portion of the brain that is likely to be involved in controlling breathing and waking during sleep. Babies born with defects in other portions of the brain or body may also be more prone to a sudden death. These abnormalities may stem from prenatal exposure to a toxic substance (cf. teratogens ), or lack of a vital compound in the prenatal environment, such as sufficient oxygen. Cigarette smoking during pregnancy, for example, can reduce the amount of oxygen the foetus receives.
However, scientists believe that the abnormalities that are present at birth may not be sufficient to cause death. Other possibly important events, which occur after birth, may include a lack of oxygen, excessive carbon dioxide intake, overheating or an infection.

The numbers of cells and proteins generated by the immune system of some SIDS babies have been reported to be higher than normal. Some of these proteins can interact with the brain to alter heart rate and breathing during sleep, or can put the baby into a deep sleep. Such effects might be strong enough to cause the baby's death, particularly if the baby has an underlying brain defect.

Some babies who die suddenly may be born with a metabolic disorder. One such disorder is medium chain acylCoA dehydrogenase deficiency , which prevents the infant from properly processing fatty acids. A build-up of these acid metabolites could eventually lead to a rapid and fatal disruption in breathing and heart functioning.


There is no easy prevention solution for SIDS, however, certain factors may decrease an infant's risk. These include:

  • Good prenatal care, which includes proper nutrition, no smoking or drug or alcohol use by the mother
  • Frequent medical check-ups beginning early in pregnancy, might help prevent a baby from developing an abnormality that could put him or her at risk for sudden death. These measures may also reduce the chance of having a premature or low birthweight baby, which also increases the risk for SIDS.
  • Once the baby is born, parents should keep the baby in a smoke-free environment.
  • Parents and other caregivers should put babies to sleep on their backs as opposed to their stomachs. If a parent is unsure about the best sleep position for their baby, it is always a good idea to talk to the baby's doctor.
  • Infants should sleep on a firm mattress or other firm surface. Fluffy blankets or covering as well as pillows, sheepskins, blankets, or comforters under the baby should be avoided. Infants should not be placed to sleep on a waterbed or with soft stuffed toys.
  • Recently, scientific studies have demonstrated that bedsharing, between mother and baby, can alter sleep patterns of the mother and baby. These studies have led to speculation that bedsharing, sometimes referred to as co-sleeping, may also reduce the risk of SIDS. While bedsharing may have certain benefits (such as encouraging breast feeding), there are not scientific studies demonstrating that bedsharing reduces SIDS. Some studies actually suggest that bedsharing, under certain conditions, may increase the risk of SIDS. If mothers choose to sleep in the same beds with their babies, care should be taken to avoid using soft sleep surfaces. Quilts, blankets, pillows, comforters, or other similar soft materials should not be placed under the baby. The bedsharer should not smoke or use substances such as alcohol or drugs which may impair arousal. It is also important to be aware that unlike cribs, which are designed to meet safety standards for infants, adult beds are not so designed and may carry a risk of accidental entrapment and suffocation.
  • Babies should be kept warm, but they should not be allowed to get too warm because an overheated baby is more likely to go into a deep sleep from which it is difficult to arouse. The temperature in the baby's room should feel comfortable to an adult and overdressing the baby should be avoided.
  • There is some evidence to suggest that breast feeding might reduce the risk of SIDS. A few studies have found SIDS to be less common in infants who have been breast fed. This may be because breast milk can provide protection from some infections that can trigger sudden death in infants.

For further, more detailed information on this topic, please refer to the reference source for this page.

The information in this page is presented in summarised form and has been taken from the following source(s):
1. The National Institute of Child Health and Human Development:

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Contact Last modified: Jun 25 2002