INFANT DEATH SYNDROME
Infant Death Syndrome (SIDS) is the diagnosis given for the sudden
death of an infant under one 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.
Because most cases of SIDS occur when a baby is sleeping in a crib,
SIDS is also commonly known as crib death.
is the leading cause of death in infants between 1 month and 1 year
of age. Most SIDS deaths occur when a baby is between 1 and 4 months
of age. African American children are two to three times more likely
than white babies to die of SIDS, and Native American babies are
about three times more susceptible. Also, more boys are SIDS victims
Are the Risk Factors for SIDS?
number of factors seem to put a baby at higher risk of dying from
SIDS. Babies who sleep on their stomachs are more likely to die
of SIDS than those who sleep on their backs. Mothers who smoke during
pregnancy are three times more likely to have a SIDS baby, and exposure
to passive smoke from smoking by mothers, fathers, and others in
the household doubles a baby's risk of SIDS. Other risk factors
include 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, and premature or low birth weight babies.
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, 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 fetus receives.
believe that the abnormalities that are present at birth may not
be sufficient to cause death. Other possibly important events occur
after birth such as lack of oxygen, excessive carbon dioxide intake,
overheating or an infection. For example, many babies experience
a lack of oxygen and excessive carbon dioxide levels when they have
respiratory infections that hamper breathing, or they re-breathe
exhaled air trapped in underlying bedding when they sleep on their
stomachs. Normally, infants sense such inadequate air intake, and
the brain triggers the babies to wake from sleep and cry, and changes
their heartbeat or breathing patterns to compensate for the insufficient
oxygen and excess carbon dioxide. A baby with a flawed arcuate nucleus,
however, might lack this protective mechanism and succumb to SIDS.
Such a scenario might explain why babies who sleep on their stomachs
are more susceptible to SIDS, and why a disproportionately large
number of SIDS babies have been reported to have respiratory infections
prior to their deaths. Infections as a trigger for sudden infant
death may explain why more SIDS cases occur during the colder months
of the year, when respiratory and intestinal infections are more
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.
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. If
there is a family history of this disorder or childhood death of
unknown cause, genetic screening of the parents by a blood test
can determine if they are carriers of this disorder. If one or both
parents is found to be a carrier, the baby can be tested soon after
Might Help Lower the Risk of SIDS?
currently is no way of predicting which newborns will succumb to
SIDS; however, there are a few measures parents can take to lower
the risk of their child dying from SIDS.
prenatal care, which includes proper nutrition, no smoking or drug
or alcohol use by the mother, and 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 birth-weight baby, which also increases the risk for SIDS.
Once the baby is born, parents should keep the baby in a smoke-free
and other caregivers should put babies to sleep on their backs as
opposed to on their stomachs. Studies have shown that placing babies
on their backs to sleep has reduced the number of SIDS cases by
as much as a half in countries where infants had traditionally slept
on their stomachs. Although babies placed on their sides to sleep
have a lower risk of SIDS than those placed on their stomachs, the
back sleep position is the best position for infants from 1 month
to 1 year. Babies positioned on their sides to sleep should be placed
with their lower arm forward to help prevent them from rolling onto
parents place babies on their stomachs to sleep because they think
it prevents them from choking on spit-up or vomit during sleep.
But studies in countries where there has been a switch from babies
sleeping predominantly on their stomachs to sleeping mainly on their
backs have not found any evidence of increased risk of choking or
some instances, doctors may recommend that babies be placed on their
stomachs to sleep if they have disorders such as gastroesophageal
reflux or certain upper airway disorders which predispose them to
choking or breathing problems while lying on their backs. 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 or other health care provider.
certain amount of tummy time while the infant is awake and being
observed is recommended for motor development of the shoulder. In
addition, awake time on the stomach may help prevent flat spots
from developing on the back of the baby's head. Such physical signs
are almost always temporary and will disappear soon after the baby
begins to sit up.
should make sure their baby sleeps on a firm mattress or other firm
surface. They should avoid using fluffy blankets or covering as
well as pillows, sheepskins, blankets, or comforters under the baby.
Infants should not be placed to sleep on a waterbed or with soft
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.
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.
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 breastfed. This may be because breast milk
can provide protection from some infections that can trigger sudden
death in infants.
Parents should take their babies to their health care provider for
regular well baby check-ups and routine immunizations. Claims that
immunizations increase the risk of SIDS are not supported by data,
and babies who receive their scheduled immunizations are less likely
to die of SIDS. If an infant ever has an incident where he or she
stops breathing and turns blue or limp, the baby should be medically
evaluated for the cause of such an incident.
some electronic home monitors can detect and sound an alarm when
a baby stops breathing, there is no evidence that such monitors
can prevent SIDS. A panel of experts convened by the National Institutes
of Health in 1986 recommended that home monitors not be used for
babies who do not have an increased risk of sudden unexpected death.
The monitors are recommended, however, for infants who have experienced
one or more severe episodes during which they stopped breathing
and required resuscitation or stimulation, premature infants with
apnea, and siblings of two or more SIDS infants. If an incident
has occurred or if an infant is on a monitor, parents need to know
how to properly use and maintain the device, as well as how to resuscitate
their baby if the alarm sounds.
Does a SIDS Baby Affect the Family?
SIDS death is a tragedy that can prompt intense emotional reactions
among surviving family members. After the initial disbelief, denial,
or numbness begins to wear off, parents often fall into a prolonged
depression. This depression can affect their sleeping, eating, ability
to concentrate, and general energy level. Crying, weeping, incessant
talking, and strong feelings of guilt or anger are all normal reactions.
Many parents experience unreasonable fears that they, or someone
in their family, may be in danger. Over-protection of surviving
children and fears for future children is a common reaction.
the finality of the child's acute death becomes a reality for the
parents, recovery occurs. Parents begin to take a more active part
in their own lives, which begin to have meaning once again. The
pain of their child's death becomes less intense but not forgotten.
Birthdays, holidays, and the anniversary of the child's death can
trigger periods of intense pain and suffering.
will also be affected by the baby's death. They may fear that other
members of the family, including themselves, will also suddenly
die. Children often also feel guilty about the death of a sibling
and may feel that they had something to do with the death. Children
may not show their feelings in obvious ways. Although they may deny
being upset and seem unconcerned, signs that they are disturbed
include intensified clinging to parents, misbehaving, bed- wetting,
difficulties in school, and nightmares. It is important to talk
to children about the death and explain to them that the baby died
because of a medical problem that occurs only in infants in rare
instances and cannot occur in them. The National Institute of Child
Health and Human Development (NICHD) continues to support research
aimed at uncovering what causes SIDS, who is at risk for the disorder,
and ways to lower the risk of sudden infant death.
with permission from
The National Institute of Child Health and Human Development
National Institutes of Health
Bethesda, Maryland 20892