SIDS (sudden infant death syndrome), also known as crib death, is the unexplained death of a child under the age of 1 year. It usually occurs when an otherwise healthy infant fails to awaken from sleep.

There is no known cause of SIDS. It occurs most often in infants between the ages of 2 months and 4 months. Approximately 2,500 infants die each year of SIDS, according to the American Academy of Family Physicians. SIDS is the leading cause of death among infants between 1 month and 1 year old.

SIDS is diagnosed only after other possible causes of death have been ruled out (e.g., accidents, abuse, undiagnosed medical problems). An autopsy, death scene investigation and evaluation of the child’s health status and medical history are conducted before a diagnosis is made.

Several factors appear to increase the risk of SIDS. Male babies, premature infants and those of American Indian or African American heritage tend to have higher rates of SIDS. Modifiable risk factors include avoiding placing babies to sleep on their stomach, and preventing prenatal and postnatal exposure to cigarette smoke and overheating. 

SIDS (sudden infant death syndrome), also known as crib death, is the unexplained and abrupt death of a baby 1 year old or younger. SIDS usually occurs among otherwise healthy infants, and is associated with sleep. In most cases, a sleeping baby simply never wakes up.

SIDS is a leading cause of death in infants. Approximately 2,500 babies die each year of SIDS, according to the American Academy of Family Physicians. Those who have died of SIDS show no signs of suffering. Most cases of SIDS involve infants between 2 months and 4 months old. The majority of cases occur at home, but some occur in childcare settings.

The cause of SIDS (sudden infant death syndrome) is unknown. However, numerous theories have been proposed regarding potential causes of SIDS.  

Theories about the potential causes of SIDS focus on three areas – physical, developmental and environmental. One theory is that a physical defect in the brainstem may prevent an infant from waking up when experiencing a lack of oxygen. Developmental theories focus on the fact that many SIDS cases occur among infants between the ages of 2 months and 4 months. This is a period of rapid changes in the body’s functioning as sleep and wake patterns are established and regulatory aspects of the cardiac, respiratory and nervous systems also develop. Any abnormality during a vulnerable period of development may affect the infant. Environmental theories focus on the infant’s exposure to various substances (e.g., cigarette smoke) either before or after birth.

No one theory has explained particular cases of SIDS. The causes may vary or may occur in different combinations for different infants. No single factor has been identified as increasing the risk of SIDS in an otherwise healthy infant. Instead, multiple factors may combine to create an increased risk of SIDS.

Certain factors popularly believed to be related to SIDS have been ruled out as causes. Despite common belief, the following do not cause SIDS:

• Immunizations
• Allergies
• Exposure to electrical or magnetic fields
• Choking or vomiting

Although the cause of SIDS is not known, certain risk factors for the condition have been identified. Risk factors are elements that increase an infant’s risk of SIDS. However, not every infant with risk factors will have SIDS and more importantly, infants with no risk factors may also die of SIDS. Risk factors may be divided into three categories: postnatal environmental, prenatal and unchangeable.

Postnatal environmental risk factors include:

• Sleep position. SIDS occurs more often among babies who are placed on their abdomen or their sides to sleep. This may increase pressure against a child’s jaw and impair breathing. Or, it may trap an infant’s exhaled breath, leading to a lack of oxygen and suffocation. Babies used to sleeping on their backs who are suddenly switched to sleeping on their stomach face a higher risk of SIDS.
  
  
• Soft or loose bedding. Infants who sleep on softer surfaces or with loose bedding are at an increased risk of SIDS. Soft surfaces include couches or waterbeds. Loose bedding may include pillows or comforters or stuffed animals.
  
  
• Exposure to smoke. Second-hand smoke may double a baby’s risk of SIDS. It is believed that exposure to smoke may affect a child’s central nervous system and may make a child harder to rouse from sleep, increasing the risk of SIDS.
  
  
• Overheating. Too much sleepwear on a baby or excessive bedding material may cause an infant to overheat while sleeping.

The mother’s environment or behavior during pregnancy may also affect her infant’s likelihood of developing SIDS. Prenatal risk factors for SIDS include:

• Smoking, alcohol consumption or recreational drug use during pregnancy
  
  
• Poor prenatal care
  
  
• Pregnancy complications (e.g., placenta previa [placenta blocks the opening to the uterus])
  
  
• Being under age 20 during first pregnancy

Non-modifiable risk factors include:

• Age. Most SIDS cases occur in children during the second, third and fourth months of life.
  
  
• Premature or low-birthweight infants. Premature babies or those weighing less than 4.5 pounds (2 kilograms) at birth have a higher risk of SIDS.
  
  
• Race. American Indian and African American babies are more likely to die of SIDS.
  
  
• Gender. More boys die of SIDS than girls.

There is no guaranteed method to prevent SIDS (sudden infant death syndrome). However, physicians have studied the syndrome for years and have developed practices that may help reduce the risk of SIDS. However, SIDS deaths still occur among infants with no risk factors and whose parents followed all of the suggested guidelines.

Putting infants to sleep on their backs has been recommended. A significant amount of research indicates an association between stomach sleeping and SIDS. In 1992, the American Academy of Pediatrics (AAP) recommended that all healthy infants be placed on their backs to sleep to help prevent SIDS. Since then, the rate of SIDS has dropped by approximately 50 percent.  

Parents who rely on other caregivers (e.g., babysitters, daycare providers, family, friends, neighbors) should ensure that everyone caring for their child always puts the infant to sleep on their back. The changes in recommendations from the AAP make this especially important. For example, grandparents may last have cared for infants 30 years ago, when back sleeping was discouraged. They should be made aware of the dangers of stomach sleeping for infants.

Side-sleep positioning is also not recommended, because infants may easily move from their side into an abdomen-down position. Parents should visually check on their sleeping baby as often as possible.

Between the ages of 4 months and 7 months, infants may be able to roll themselves over and may not choose to remain on their backs while sleeping. By this age, however, the peak risk of SIDS has decreased. Parents of infants with chronic reflux or certain airway obstructions should consult their pediatrician about the best position for sleeping for their infant.

Placing infants on their backs does not increase the risk of choking. A flat spot on the head (positional plagiocephaly) may sometimes develop as the result of sleeping on the back. However, this spot usually rounds out as a child grows older and learns to sit up. In addition, supervised “tummy time” (short periods of time when infant is placed on the abdomen while awake) is recommended to help strengthen an infant’s neck and shoulder muscles. This may be appropriate after a diaper change or when the baby wakes from a nap. 

The back sleeping position is the most important recommendation of the AAP to lessen the risk of SIDS. Other AAP recommendations include:

• Place baby on a firm mattress. Avoid placing an infant on a waterbed or other soft surface (e.g., beanbag chair, sofa, cushion) that may restrict breathing.
  
  
• Avoid the use of soft, fluffy blankets, toys or pillows in a crib with an infant, which may also restrict breathing. Bumper pads on a crib should be thin and firm, not pillow-like.
  
  
• Maintain a smoke-free environment. Ensuring a baby is not exposed to second-hand smoke may help prevent the risk of SIDS.
  
  
• Keep baby in a crib close to parents. Putting babies to sleep in their own crib or bassinet in the same room as parents is associated with lowered rates of SIDS. Parents should avoid sleeping with infants in the same bed because of the risk of accidental suffocation.
  
  
• Use a pacifier when putting a baby to sleep. The AAP added this recommendation in 2005. The use of pacifiers has been associated with a decreased risk of SIDS. If breastfeeding, avoid using pacifiers for the first month until breastfeeding has become an established routine with the infant. Pacifiers should not be forced on infants who refuse them. A pacifier that falls out of a baby’s mouth while asleep should not be placed back into the infant’s mouth.
  
  
• Avoid overheating or overbundling. Dress the baby lightly. Keep the room temperature comfortable for a lightly clothed adult. Cover a baby only up to the chest or shoulders with a light blanket, if necessary (sides of the blanket may be tucked in along the bottom half of the crib). A baby’s head and face should remain uncovered during sleep. Excessive warmth may make it difficult for a baby to awaken. Damp hair, flushed cheeks, heat rash and rapid breathing may indicate that a baby is overheated.

SIDS and other problems in infancy may be prevented by:

• Avoiding smoke, alcohol and drugs while pregnant
• Receiving early, regular prenatal care
• Taking the infant to regular well-child checkups
• breastfeeding to boost a baby’s immune system

Families that lose a child to SIDS (sudden infant death syndrome) suffer a devastating loss. Parents often suffer from both grief and guilt when their child dies of SIDS. It is important to realize that SIDS may occur no matter how much a parent loves or tries to protect their child. SIDS may also strain a marriage, and grieving parents may not be able to comfort each other.

Parents of SIDS infants should seek emotional support. They may ask their physician about available community resources, support groups or even other SIDS parents who may be available to talk. Sharing thoughts and feelings in online chat rooms, with friends, family members and counselors may also help. Some national groups (e.g., Sudden Infant Death Syndrome Alliance) may be able to provide grief counseling, support and referrals.

At the time of death, it is important for parents to be able to hold their child one last time. Some parents may want to keep a lock of hair or make footprints or handprints of their baby. Parents may find it helpful to memorialize their child. A funeral or memorial service with photos and the child’s favorite toys or blanket may help commemorate the child’s life and help surviving family members to acknowledge the child’s death. In addition, it is important that grieving parents continue to maintain their physical health (e.g., eat healthy foods, get regular exercise, get adequate rest).

Preparing questions in advance can help parents have more meaningful discussions with their child’s physicians regarding their concerns. The following questions related to sudden infant death syndrome (SIDS) may be helpful:

1. Does my baby have an increased risk of SIDS? If so, why?
   
   
2. What can I do to prevent SIDS?
   
   
3. I always put my baby to sleep on his/her back. How can I be sure others who look after my baby will do the same?
   
   
4. Are there times when stomach sleeping is safe for my baby?
   
   
5. Will smoking in the house harm my baby? Will it increase my baby’s risk of SIDS?
   
   
6. What can I do about the flattened spot my baby gets on the head from sleeping on his/her back?
   
   
7. My baby can now roll over onto his/her stomach during sleep. Should I turn him/her back over?
   
   
8. Is it safe to take our baby to bed with us?
   
   
9. At what age is my child no longer at risk of SIDS?
   
   
10. Our child died of SIDS. I still don’t understand what happened. Will we ever know what caused it?
    
    
11. What are the chances that additional children of ours may die of SIDS?
    
    
12. Can you recommend a support group for SIDS to help us deal with our loss?