New research published this month in the journal Pediatrics finds that, in addition to a safe sleep environment, other factors including exposure to smoking, lack of prenatal care and limited breastfeeding affect a baby’s risk of SIDS. While researchers are learning more about the “underlying biology” of SIDS, they do believe a perfect storm could be created when infants who have an underlying risk are introduced to one of these identified external factors during a critical period of development. They are hopeful, however, that as more information is presented, changes will occur to further reduce the incidence of SIDS, as we have seen with the successful “Back to Sleep” campaign. From 1983 to 2012, SIDS deaths declined 71 percent, with the steepest decline during the years of that campaign from 1994 to 1996.
What is sudden infant death syndrome (SIDS)?
Sometimes called “crib death,” SIDS is the sudden and unexplainable death of an infant under one year of age while sleeping. Occurring most often between the ages of two and four months, it is one of the leading causes of death for babies from one to 12 months of age. In most cases, the baby is healthy and death is sudden and unpredictable, usually happening during a sleep time.
What causes SIDS?
The exact causes of SIDS are unknown, though there are some known risk factors. Some are preventable, but others are not. Evidence has indicated that the following are some of the risk factors for SIDS:
- Brain abnormalities. Studies have shown that many SIDS babies have abnormalities in a part of the brain that probably helps control breathing and waking during sleep. Babies with defects in other portions of the brain can also be more prone to SIDS, in addition to babies who may have been exposed to a toxic substance, cigarette smoke or low amounts of oxygen while in utero.
- Happenings after birth. Overheating, infection, lack of oxygen and excessive carbon dioxide intake may be linked to SIDS. Lack of oxygen and excessive carbon dioxide levels may be comprised of the following:
- Breathing problems caused by respiratory infection
- Re-breathing air that is trapped under a blanket
Normally, when a baby senses that he or she is not getting enough air, his brain wakes him up and he cries, changing his heart rate and breathing patterns to make up for lost oxygen. Researchers believe this may explain why babies who sleep on their stomachs are more at risk of SIDS, as well as the large number of babies who died from SIDS reportedly had respiratory infections prior to their death. SIDS is also more common during the colder months of the year, when respiratory infections are more common.
- Immune system problems. Some immune system cells and proteins in SIDS babies have been found to be higher than normal, potentially interacting with the brain, changing heart rate and breathing during sleep. This could potentially put the baby into a deep sleep, with effects strong enough to cause the baby’s death, especially if the baby has an underlying brain abnormality.
- Metabolic disorder. Some babies who die suddenly may be born with a metabolic disorder, such as a medium chain acyl-CoA dehydrogenase deficiency, which prevents the baby from properly processing fatty acids. Over time, a build up of these acid metabolites could lead to a rapid and fatal interruption in breathing and heart function. Genetic screening of the parents by a blood test can determine if they are carriers of this disorder, when a family history is present. If one or both parents are found to be a carrier, the baby can be tested soon after birth.
Who is at risk for SIDS?
More than 4,500 babies in the United States die of SIDS each year. Some babies are more at risk than others. For example, SIDS is more likely when a baby is between two and four months old, it is more common in boys than girls and most deaths occur during the fall, winter and early spring months.
Factors that may place a baby at higher risk of dying from SIDS include the following:
- Babies who sleep on their stomach rather than their back
- Babies who sleep on soft surfaces, have loose bedding and are covered by many blankets
- Babies who share a bed with other children (including twins or other infants), adults or pets
- Mothers who smoke during pregnancy (three times more likely to have a baby die of SIDS)
- Exposure to passive smoke from smoking by mothers, fathers and others in the household (doubles a baby's risk of SIDS)
- Mothers who are younger than 20 at the time of their first pregnancy
- Babies born to mothers who had no or late prenatal care
- Premature or low birthweight babies
What can be done to decrease the risk for SIDS?
There currently is no way of predicting which babies will die from SIDS. However, there are a few measures parents can take to lower the risk of their baby dying from SIDS, including the following:
- Prenatal care. Early and regular prenatal care can help reduce the risk for SIDS. Proper nutrition, no smoking or drug or alcohol use by the mother and frequent medical checkups 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. The risk of SIDS is higher for babies whose mothers smoked during pregnancy.
- Put your baby on his or her back for sleep, even at naptime. Parents and other caregivers should put babies to sleep on their back as opposed to on their stomach or side. Studies have shown that placing babies on their back to sleep has reduced the number of SIDS cases by as much as a half in countries where babies had traditionally slept on their stomach. The back sleep position is the best option from birth until the baby can roll over by him or herself.
Although many parents are afraid babies will choke on spit-up or vomit if placed on their back, studies have not found any evidence of increased risk of choking or other problems.
Because of safety concerns, always check with your infant’s doctor before elevating the head of the crib if he or she has been diagnosed with gastroesophageal reflux.
- Place baby on his or her stomach while awake and under supervision. A certain amount of tummy time while the infant is awake and being observed by the caregiver is recommended for motor development of the shoulders and strengthening of the neck and tummy muscles. 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. Avoid using infant seats, car seats, strollers, infant carriers, and infant swings for routine sleep and daily naps. These may lead to obstruction of an infant's airway or suffocation. Always place cribs, bassinets or play yards in hazard-free areas—those with no dangling cords or wires—to reduce the risk for strangulation.
- Proper bedding. Make sure that your baby sleeps on a firm mattress or other firm surface covered by a fitted sheet. Do not use fluffy blankets or comforters under the baby. Do not let the baby sleep on a waterbed, sofa, sheepskin, a pillow, or other soft materials. When your baby is less than a year old, do not place soft stuffed toys, pillows or bumper pads in the crib with him or her. Some babies have been smothered with these soft materials in the crib.
- Temperature control: Avoid overheating. Avoid over bundling, over dressing or covering your infant’s face or head. This will prevent him or her from getting overheated, reducing the risk for SIDS. Babies should be kept warm, but they should not be allowed to get too warm. 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.
- Same room / room-share. Place baby's crib or bassinet in parents' room for first six months. The risk for SIDS is reduced when a baby sleeps in the same room as the mother. However, the baby should be in his or her own crib, bassinet or Moses basket.
- Avoid bed-sharing. Recently, scientific studies have shown that bed-sharing between mother and baby can alter sleep patterns of the mother and her baby. While bed-sharing may have certain benefits (such as encouraging breastfeeding), there are no scientific studies demonstrating that bed-sharing reduces SIDS. Some studies suggest that bed-sharing, under certain conditions, may actually increase the risk for SIDS. Avoid putting your baby to sleep in a bed with other children or on a sofa with another person, as these have been found to increase the risk for SIDS. Infants can be brought into the parents' bed for feedings and comforting but should be returned to their own crib for sleep. Bed-sharing is not recommended for twins or other multiples.
- Smoke-free environment. Do not smoke when you are pregnant and do not let anyone smoke around your baby. Smoking in pregnancy is a major risk factor for SIDS. Babies and young children exposed to smoke have more colds and other diseases, as well as an increased risk for SIDS.
- Pediatric health care and immunizations. If your baby seems sick, call your doctor right away. Parents should take their babies for regular well baby checkups and routine immunizations. Claims that immunizations increase the risk for SIDS are not supported by research. In fact, recent evidence shows that fully vaccinating your child lowers the risk for SIDS. If a baby 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.
- Breastfeed your baby. Breast milk only is recommended for at least six months. Breastfeeding lowers the risk for SIDS. It also protects your baby from many health problems.
- Home monitors for babies at risk. Avoid using cardiorespiratory monitors and commercial devices—wedges, positioners and special mattresses—to help decrease the risk for SIDS and sleep-related infant deaths. Sleep positioning devices have never been shown to prevent SIDS. In rare cases, these devices have actually caused infant deaths. Although 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. In 1986, the National Institutes of Health recommended that home monitors not be used for babies who do not have an increased risk for sudden unexpected death. The monitors may be recommended, however, for babies who have experienced one or more severe episodes during which they stopped breathing and required resuscitation or stimulation, premature babies with apnea (stopping breathing) and siblings of two or more SIDS babies. If an incident has occurred, or if a baby 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.
- Offering pacifiers during sleep time. The American Academy of Pediatrics recommends that pacifiers be used for the first year of life during routine sleep and nap time. Pacifiers should be cleaned and replaced often. Talk with your baby's health care provider about when you should use a pacifier.