Sudden infant death syndrome (SIDS) is the common term used when describing the unexplained and sudden death of a baby generally younger than 1 year old, where there is no known cause of death.
New parents do everything they can to keep their babies healthy. But sometimes, a baby who seems perfectly fine passes away for no clear reason.
Because SIDS often happens when a baby is asleep, you might also hear it called crib death or cot death.
The fact that it’s so hard to predict makes SIDS one of the leading causes of death for babies younger than 12 months in the U.S., behind birth defects and preterm birth/low birth weight, according to the CDC.
In the U.S., around 3,400 babies die each year from sudden unexplained infant deaths (SUID). SUID includes unknown causes of death, SIDS, as well as accidental suffocation and strangulation in bed. As of 2020, about 41% of these SUID deaths were due to SIDS.
SIDS Causes
Undiagnosed health problems and SIDS
Doctors aren’t sure what causes SIDS, but they have a few ideas. Some babies have a gene or a change to their genes that causes certain health problems that can lead to SIDS.
Other babies are born with problems in the part of their brain that controls breathing, heart rate, blood pressure, temperature, and waking from sleep.
Stress and SIDS
Stress from things such as poor sleep position, secondhand smoke, or a respiratory infection can be a risk for SIDS.
There is also evidence that prolonged and repetitive stressful or painful experiences for a baby before or after it’s born could also potentially be a risk factor for SIDS.
SIDS and vaccines
Multiple research studies and safety reviews suggest that there is no connection between vaccines and SIDS.
Babies receive several vaccines between 2 and 4 months of age when the risk of SIDS is at its highest. So, there have been questions about whether vaccines play a role. But repeated medical studies have shown no evidence of any relationship between vaccines and SIDS.
In fact, since the mid-1980s, SIDS cases have fallen by more than 50%, while the number of vaccines typically given to babies has risen. Some research suggests that vaccines may actually help prevent SIDS.
When Does SIDS Most Often Occur?
SIDS occurs most often when babies are between 2 and 4 months old. But it can happen at any time during the first year of life.
How common is SIDS?
SIDS isn't very common. Nearly 1,400 infants die from SIDS each year in the U.S.
Evidence shows that SIDS rates have noticeably declined since 1990 when there were 130.3 deaths from SIDS per 100,000 live births. As of 2020, the CDC reported 38.4 deaths from SIDS per 100,000 live births.
Risk Factors for SIDS
You can’t predict whether SIDS will affect your family, but there are a few things that make it more likely:
Sex. SIDS is more likely to affect boys, but only slightly.
Race. SIDS happens most often among African Americans, Native Americans, and Alaska natives. Doctors aren’t sure why.
Birth weight. SIDS is more likely in preemies, especially those born very small, than full-term babies.
Family history. A baby’s odds are higher if a sibling or cousin passed away from SIDS.
Maternal health. SIDS is more likely to happen to a baby whose mother:
- Is younger than 20
- Doesn’t get good prenatal care
- Smokes, uses drugs, or drinks alcohol while pregnant or during the baby’s first year
How to Prevent SIDS
There are a few easy things you can do to prevent SIDS and keep your little one safe:
Sleep positions to prevent SIDS
Put your baby on their back to sleep. Once they can roll over on their own, it’s safe for them to sleep on their tummy. Until then, remember this phrase -- “back to sleep.” It’ll help lower the risk of SIDS for your baby.
Safe bedding to prevent SIDS
Choose a firm, flat surface for your baby’s bed, and use tight-fitting sheets. Keep pillows, blankets, and other objects out of their sleep area until they are at least 1 year old. You can swaddle them for warmth, but only until they learn how to roll over.
Sharing a bedroom to prevent SIDS
When your infant is young, you should sleep in the same room but not in the same bed. Sharing a room with your baby can cut their chances of SIDS by half. But sleeping in the same bed with them raises their odds. Try not to fall asleep while sitting up and holding your baby.
Pacifier use, vaccinations, and breastfeeding
Use a pacifier, vaccinate, and breastfeed if you can. All three lower the risk of SIDS.
Temperature impact on SIDS risk
Keeping babies cool while they are asleep can help reduce the risk of SIDS. Don’t overdress them when you put them down. Their room should be cool and comfortable. You can use a special wearable blanket (called a sleep sack) that covers their body and leaves their face uncovered.
Maternal substance use and SIDS risk
Don’t smoke, drink, or use drugs. It’s bad for your growing baby when you’re pregnant. Using drugs and alcohol might even make you a less alert or careful parent. Breathing in secondhand smoke can also raise the odds of SIDS.
Pregnancy health and SIDS risk
Stay healthy during pregnancy. Avoid risky behaviors, eat healthy food, and see your doctor for regular checkups.
Takeaways
Sudden infant death syndrome (SIDS) happens when a baby passes away for no clear reason. Though doctors aren’t exactly sure what causes SIDS, they do know that babies are most likely to die of SIDS between 2 and 4 months. Still, it can happen at any time during your baby's first year of life. There are things parents and guardians can do to prevent SIDS. These include putting babies on their backs to sleep, choosing safe bedding, using a pacifier, vaccinating, and staying healthy during and after pregnancy.
SIDS FAQs
Are there any warning signs of SIDS?
No. Deaths from SIDS come without warning in almost all cases. It’s critical to use safe sleep practices, such as placing your baby on their back to sleep, to help prevent SIDS.
When can I stop worrying about SIDS?
SIDS deaths occur most often during the first year of a baby's life. About 90% of SIDS deaths occur before the age of 6 months. Generally, after a baby turns 1 year old, parents can be less worried about SIDS.
Why does SIDS peak at 2-4 months?
Most research shows that the peak risk age for SIDS, 2-4 months, has to do with the baby’s timeline of brain development. Between birth and 4 months, the brain is doing the most development around breathing control and wakefulness.
When does SIDS risk decrease?
SIDS is much less common after 8 months of age, and the risk goes down further as a baby approaches age 1. Doctors still recommend that parents and caregivers continue to follow all SIDS prevention measures until a baby’s first birthday.
