Sudden infant death syndrome (SIDS) or cot (crib) death

Sudden infant death syndrome (SIDS) or cot (crib) death

Sudden infant death syndrome (SIDS) is the most frightening thing for parents to the extent that they avoid reading about it.

But parents of babies under the age of one should be aware of and take valid measures.

What is sudden infant death syndrome (SIDS)?

The definition of SIDS is a sudden and unexplained death of an infant of up to the age of one year old in his sleep. The exact definition requires a post-mortem and a criminal examination of the place of death, in order to identify medical causes such as birth defects, infections or abuse.

Although since 1992 there is a significant decrease in SIDS in the United States (the year that the campaign of sleeping on the back started), this is still the most common cause of death of babies age one month to a year (about 1500 cases every year in the United States compered to 7000 cases every year up to 1992).

Today, there is a separate definition for SIDS and similar medical conditions which include suffocation in bed. The more general definition is sudden unexpected infant death (SUID) but for the purpose of this article since there is a great overlap between the conditions and especially the ways to prevent them, I will combine the two and refer only to SIDS.

Are there any medical conditions related to an increased risk of SIDS?

Many studies as well as postmortem autopsies showed endless medical variables – anatomical, biochemical, endocrinological, neurological and genetic factors between infants after SIDS and healthy babies.

From my experience in medicine, when there are many (or too many) reasons for a single medical condition, it is clear that there is no single specific medical explanation. In addition, there is no current test for children that can be done in advance, to be able to determine that a certain child is at high risk.

Are there any environmental risk factors in children with SIDS compared to other children?

Yes. The environmental risk factors can be divided into two groups: preventable and non-preventable factors.

Non-preventable factors for SIDS:

Genetic factors – many genetic factors have been found both in research and in clinical level to be associated with SIDS, such as genes coding for channels involved in the child’s heart function and rate, genes related to serotonin secretion, inflammation and to the autonomic nervous system. However, at this point there is no particular test recommended in children that can determine who is at high risk and who is not. We can say that perhaps genetic predisposition combined with environmental factors and risk factors (sleeping on the stomach for example) lead to SIDS.

Socioeconomic status – SIDS occurs in all socioeconomic levels but is more common in low socioeconomic population.

Age – SIDS is more common in babies aged 1-4 months and most events occur up to the age of 6 months.

Season – SIDS is mostly common in the winter, possibly because of overheating the room, the use of blankets or viral respiratory infections.

Gender – SIDS is more common in boys than girls by approximately 30-50%.

Family – siblings of babies that have died from SIDS are at high risk.

Infections – viral infections involving the upper respiratory system (simple cold) are found as risk factor for SIDS. That might be one of the reasons there are more cases during winter.

Preventable factors for SIDS:

Pregnancy related factors – a number of intrauterine factors have been shown to increase the risk of SIDS, some can be prevented and some less so. Among them are poor pregnancy follow-up, low birth weight, premature babies and more.

Smoking – there is a great link between exposure to cigarette smoke during pregnancy and SIDS. After reduction in SIDS incidence, followed by the instruction to place babies to sleep on their back, infants of women who smoked during pregnancy are still four times more likely to have SIDS. There is also an independent link between father smoking during the pregnancy.
Furthermore, the risk of babies who have been exposed to environmental smoke only after birth (and not during pregnancy) doubles. There is a correlation between the number of people who smoke around the baby and to the number of cigarettes. Therefore, parents (both mums and dads) who considered smoking during pregnancy or after birth – please don’t.

Drug and alcohol use – drug use during pregnancy or after the birth is associated with significant increase of SIDS rates. The effect of alcohol use is slightly more difficult to prove but the association is similar. A study in New Zealand showed that babies of mothers who smoked cannabis at night (not during day time…) doubled the chances of cot death.

Sleeping position – laying baby on his front is a major risk factor for SIDS. The risk even grows in babies who usually sleep on their back and are placed on their front on a certain night. This emphasizes that all care givers should put baby on its back.

Sleeping on the side doubles the risk of SIDS. In babies that during the night turn from sleeping on the side to sleeping on the front, the risk is even higher.

Many parents assume that sleeping on the back increases the prevalence of other medical conditions from restless sleeping to reflux, colic and vomiting. This is not true. On the contrary. Babies who sleep on their backs have less fever when they are one month old, less sleep problems at six months and less ear infections at a young age.

In order to strengthen the shoulder girdle and to encourage proper development of a baby sleeping on its back, it is important to determine specific times, only when awake, of laying the baby in the prone position.

Baby’s sleeping surrounding – soft bedding including, thick blankets, soft toys and so on, have been found to increase the risk of SIDS. If we want to elevate baby’s head in cases of reflux or cold, use two thick books under the legs of the top of cot, creating a sleeping angle for the whole bed rather than using pillows or as such inside the cot.

Use a tight fitted sheet and cover baby with a thin blanket, tightening it to the edge of the cot, pelvis height. Avoid the use of head bump.

Heating baby’s environment – over heated bedroom or over clothing, including head cover have been found risky to cot death. The recommended temperature is about 22℃. The temperature outside the room is not a factor.

Co-sleeping – with parents or siblings in the same bed or sofa is a significant risk factor. On the other hand, sharing a room in separate beds lowers the risk of SIDS.

Baby’s nutrition – breastfeeding has been found to be a preventative factor in SIDS by 45%. Other advantages of breastfeeding are addressed in the following link.

Using a pacifier – most studies show that the use of pacifier when going to sleep lowers the prevalence of cot death. The advantage of going to sleep with a pacifier continues even when the pacifier falls out during sleep. Meaning there is no need to put it back in baby’s mouth after he falls asleep.

Vaccinations – SIDS is more common among babies that have not been vaccinated opposed to vaccinated babies, although there might not be a direct connection. In babies properly vaccinated there is no association between SIDS and the timing of the vaccines.

Premature babies – preterm babies are at risk of cot death with almost a direct link to the week of the birth. The more premature the baby, the risk is higher. It is found that premature babies sleep more on their backs also after being released from hospital. While they were monitored at hospital, they are not at home. Nevertheless, the prevalence is higher also among premature babies that sleep on their backs.

Are home monitors devices recommended?


There is no monitor device in the market that has been proven to reduce the risk of SIDS. Even if we did use different kinds of monitors and sensors, they do not help and sometimes even cause stress. Yet, it seems it will be difficult to abandon the use of these devices, therefore I have two recommendations for parents wanting to invest in buying a monitor / sensor:

1. Read this article carefully, embrace all the preventing methods and then buy the device you wish.
2. From my experience, I recommend that when the device beeps, go to baby’s room, turn on the light and first of all look at the baby, mostly his color and breathing movements in the chest area. Most times you will find a relaxed baby with normal color and breathing (chest properly rising and lowering). Most beeping sounds from these devices are false alarms that usually stress out the parents and causing them to react irrationally.

In summary:

How to reduce the risk of SIDS (cot death)?

The American Academy of Paediatrics has established a few guidelines for reducing the risk of cot death. I added to these recommendations some points also from my local ministry of health (Israel)

1. Place baby to sleep only on it’s back. Not on the front or the side.
2. Use a hard sleeping surface. Avoid putting baby to sleep on a sofa, couch, water bed, car seats, strollers and as such.
3. Breastfeeding is also recommended for reducing the risk of cot death. You can find more on the benefits of breastfeeding here.
4. It is recommended for the baby to sleep in the same space as the parents, using a bed and mattress that meet national safety standard. If baby is brought to bed for calming or feeding, once this is completed, he / she should be put back to sleep in a separate bed.
5. Avoid putting pillows, cushions, thick blankets and soft toys in baby’s bed.
6. Cover the mattress in a tight fitted sheet and cover baby in a blanket tightened to the edge of the bed, pelvis height.
7. Avoid using head bumps.
8. Avoid over dressing and overheating. The recommended room temperature is about 22℃.
9. Offer pacifier before sleep. In case the pacifier drops out of baby’s mouth after falling asleep there is no need to put it back. It is advised to offer breastfeeding babies the use of pacifier only after the breastfeeding is established.
10. Avoid smoking during pregnancy and smoking in the baby’s surrounding after birth.
11. It is recommended to have regular follow-ups during pregnancy.
12. Routine vaccines should be administered.

I truly hope that this article will reach as many parents, in order to lower the incidence of this devastating event.

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2 Responses
  1. Nancy Ely

    Thank you, great article. Particularly relevant because I have a 3 month old granddaughter!

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