Sudden infant death syndrome (SIDS) is the unexpected, sudden death of a child under age 1. An autopsy does not show an explainable cause of death.

Crib death; SIDS

The cause of SIDS is unknown. Many health care providers and researchers now believe that SIDS is caused by many factors, including:

• Problems with the baby's ability to wake up (sleep arousal)
• Inability of the baby's body to detect a buildup of carbon dioxide in the blood

SIDS rates have gone down sharply since providers began recommending that babies be put on their backs or sides to sleep to reduce the chance of problem. However, SIDS is still a major cause of death in infants under 1 year old. Thousands of babies die of SIDS in the United States each year.

SIDS is most likely to occur between 2 and 4 months of age. SIDS affects boys more often than girls. Most SIDS deaths occur in the winter.

The following may increase the risk for SIDS:

• Sleeping on the stomach
• Being around cigarette smoke while in the womb or after being born
• Sleeping in the same bed as their parents (co-sleeping)
• Soft bedding in the crib
• Multiple birth babies (being a twin, triplet, or member of a larger multiple birth)
• Premature birth
• Having a brother or sister who had SIDS
• Mothers who smoke or use illegal drugs
• Being born to a teen mother
• Short time period between pregnancies
• Late or no prenatal care
• Living in poverty situations

While studies show that babies with the above risk factors are more likely to be affected, the impact or importance of each factor is not well-defined or understood.

Almost all SIDS deaths happen without any warning or symptoms. Death occurs when the infant is thought to be sleeping.

Several organizations offer resources and support services for people who have experienced the loss of a child from SIDS.

If your baby is not moving or breathing, begin CPR and call 911 or the local emergency number. Parents and caregivers of all infants and children should be trained in CPR.

The American Academy of Pediatrics (AAP) recommends the following:

Always put a baby to sleep on its back. This includes naps. Do not put a baby to sleep on their stomach. Also, a baby can roll onto their stomach from their side, so this position should be avoided.

Put babies on a firm surface (such as in the crib) to sleep. Never allow the baby to sleep in bed with other children or adults, and do not put them to sleep on other surfaces, such as a sofa.

Let babies sleep in the same room (not the same bed) as parents. If possible, babies' cribs should be placed in the parents' bedroom to allow for night-time feeding.

Avoid soft bedding materials. Babies should be placed on a firm, tight-fitting crib mattress without loose bedding. Use a light sheet to cover the baby. Do not use pillows, comforters, or quilts.

Make sure the room temperature is not too hot. The room temperature should be comfortable for a lightly-clothed adult. A baby should not be hot to the touch.

Offer the baby a pacifier when going to sleep. Pacifiers at naptime and bedtime can reduce the risk for SIDS. Health care professionals think that a pacifier might allow the airway to open more, or prevent the baby from falling into a deep sleep. If the baby is breastfeeding, it is best to wait until 1 month before offering a pacifier, so that it doesn't interfere with breastfeeding.

Do not use breathing monitors or products marketed as ways to reduce SIDS. Research found that these devices do not help prevent SIDS.

Other recommendations from SIDS experts:

• Keep your baby in a smoke-free environment.
• Mothers should avoid alcohol and illegal drug use during and after pregnancy.
• Breastfeed your baby, if possible. Breastfeeding reduces some upper respiratory infections that may influence the development of SIDS.
• Never give honey to a child younger than 1 year old. Honey in very young children may cause infant botulism, which may be associated with SIDS.

Published Date: July 01, 2025
Published By: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Hauck FR, Carlin RF, Moon RY, Hunt CE. Sudden infant death syndrome. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 423.

Kumar V, Abbas AK, Aster JC, Deyrup AT, Das A. Genetic and pediatric diseases. In: Kumar V, Abbas AK, Aster JC, Deyrup AT, Das A. eds. Robbins & Kumar Basic Pathology. 11th ed. Philadelphia, PA: Elsevier; 2023:chap 4.

Moon RY, Carlin RF, Hand I. Task force on sudden infant death syndrome and the committee on fetus and newborn. Sleep-related infant deaths: updated 2022 recommendations for reducing infant deaths in the sleep environment. Pediatrics. 2022;150(1):e2022057990. PMID: 35726558 pubmed.ncbi.nlm.nih.gov/35726558/.