The sudden and unexpected death of an infant is one of the most emotionally devastating occurrences a parent can experience. It’s emotional toll ranks up there with delivering a stillborn infant. A seemingly healthy infant, growing and thriving, is suddenly found dead in its bed and no one can find a reason why. He or she was a precious child whose parents were blessed with a new life and a growing family. Then tragedy struck.
Sudden Infant Death Syndrome is a term used to describe the death of an infant under 12 months of age for which, after investigation, an immediate cause or explanation cannot be found. Each year in the United States, approximately 3400 infants die suddenly and unexpectedly, and of these, 1400 are diagnosed as SIDS. For many years, SIDS has been a leading cause of infant death, and despite the best efforts by researchers, a definitive cause has yet to be found. This a huge concern for doctors who work to find preventive measures and for parents whose anxiety levels are raised by the fear of it happening to them.
Risk factors for SIDS fall into two categories: modifiable and non-modifiable; factors you can and can’t control. Non-modifiable risks include premature (“preterm”) birth, male gender, and low birth weight. Male infants are 21% more likely to die of SIDS, and the lower the birth weight, the greater the risk of SIDS. These plus socioeconomic factors (poor sleep environment, lack of prenatal and newborn care, and lack of breast feeding) are non-modifiable conditions. Infants that sleep on loose bedding or have toys, pillows, or crib bumpers in their beds have higher SIDS risk. Infants delivered from mothers without prenatal care or who have limited, or no, newborn care are at increased risk, as well.
Modifiable risk factors—factors you can do something about—include sleep position, tobacco exposure, maternal alcohol use, sleeping with others, or sleeping in a non-bed environment (couch, chair, infant carrier, etc.). Breast feeding is recommended for up to 6 months of age and plays a role in SIDS prevention. Maternal breastfeeding is known to be preferable nutritionally, but also lowers the chances of SIDS.
Since a cause for sudden infant death has not been identified, the focus of treatment has been on the control or elimination of circumstances that may well contribute to sudden infant death; those modifiable risk factors. The greatest emphasis has been on sleep positioning. Infants are recommended to lay on their backs, face up, and not on their side or abdomen. Since 1992, the supine sleep positioning has been actively advocated for infants through the “Back to Sleep” campaign. It resulted in a reduction of the frequency of sudden infant death, but not a complete elimination of the problem. Rates have leveled off, but deaths still occur.
Besides the supine sleeping position, preventive measures such as breast feeding, flat, firm sleeping surfaces, pacifiers, and avoidance of maternal alcohol intake during gestation and tobacco smoke exposure after birth. Additionally, the infant’s “independent sleep surface should be in the parents’ bedroom for 6, and preferably 12, months.” The sleep surface should be firm and flat covered by tight-fitting bedding and free of accessory items (toys, rattles, pillows, etc.). Overheating of the bedroom should be avoided, as well.
My concern, and that of many others, was that the supine sleeping position could result in the aspiration of regurgitated formula. Newborns have incompletely developed gastroesophageal sphincters, causing stomach contents to freely reflux into the mouth where they may be aspirated into the airway. Observational studies have shown, however, that aspiration is not increased by the infant laying on its back. Supine positioning can also result in flattening of the back of the infant’s head. This can be lessened by supervised, intermittent prone sleep positioning.
In 40 years of practice, I did not have a case of SIDS. However, I had one patient whose third child had succumbed to a crib death prior to her becoming my patient. Anxiety about future such incidents was a concern for her, but not to the level of it disrupting her life. She came to me as a new OB patient already having two healthy sons, and the history of SIDS in her third child. Her pregnancy went well resulting in twin sons who grew and thrived normally with no threat of trouble. I suspect she lost a lot of sleep in those first two years after their birth, though.
Sudden Infant Death Syndrome is a family tragedy that has unknown origins and is completely unpredictable. There is no set of circumstances that signal it may happen. But there are multiple common sense, responsible, preventive measures parents can use to minimize the likelihood of it occurring. We must hope researchers can determine the cause of SIDS, and that measures to counter it can be found, saving families this tragedy.
References: Darrow HJ, Carman KA, Wheeler V. Sudden Infant Death Syndrome: Common Questions and Answers. Am Fam Phys 2025 February;111(2):164-170.
Thach BT, Davies AM, Koenig JS. Pathophysiology of Sudden Upper Airway Obstruction in Sleeping Infants and its Relevance for SIDS. Ann NY Acad Sci. 1988 August;53(1):314-328.
Aldridge CM, Keene KL, Normeshie CA, Mychaleckyj JC, Hauck FR. Metabolomic profiles of Infants classified as Sudden Infant death syndrome: a case-control analysis. eBioMedicine 2025;111:105484.
ADDENDUM
RECOMMENDATIONS TO REDUCE THE RISK OF SIDS
FACTOR: RECOMMENDATIONS:
Bedding Loose bedding, accessories should not be placed in sleep environment
Breast Feeding Recommended for first six months of life. Any is better than none
Monitors These devices do not reduce risk of SIDS. Not substitute for guidelines
Pacifier Use Use at sleep onset is protective.
Prenatal Care Always a helpful recommendation
Room Sharing Infant should sleep in caregivers’ room for 6-12 mos, not in same bed
Sleep Attire Swaddle ok til infant can roll over. Room temp at comfortable level
Sleep Position Under 12 mos infant should be placed in supine (on its back) position
Sleep Surface Flat, firm; not in car seat, stroller, or upright device
Smoking Infant exposure to tobacco smoke should be avoided
Alcohol, Drugs Avoid both during pregnancy
Surface Sharing Infant should always be on an independent sleep surface.
