SIDS manifests itself in the sudden and unexpected death of an apparently healthy infant, often in the complete absence of premonitory signs and plausible causes.
Almost always the death remains unexplained even after post-mortem examinations.
Grief support for families affected by SIDS is important, as the infant’s death is sudden and apparently without cause, resulting in an unpredictable and unexplained tragedy that leaves the parents in inconsolable grief, resistant even to long sessions of psychotherapy and antidepressant drug support.
Since cot death has no witnesses, it is often associated with an investigation in search of possible guilt on the part of one or both parents.
Rates of cot death
The syndrome affects children in the first 12 months of life and is still the leading cause of death of healthy babies born in industrialised countries.
In Italy it had an incidence of about 0.5 per thousand in 2011 (23 children under 5 years of age, 1.3% of total deaths in the reference period).
Data for the years 2004-2011 for the Piedmont region show an average SIDS mortality rate of 0.09 per 1000.
It is the most common cause of death between one month and one year of age.
About 90 per cent of cases occur before the age of six months, with the peak of cases between two months and four months of age.
SIDS is more common in boys than girls.
SIDS accounts for about 80% of sudden unexpected infant deaths (SUIDs).
Are there ‘premonitory’ symptoms of cot death, SIDS?
Many parents wonder if it is possible to tell by a few small signs that their baby is at risk of being affected by this syndrome, so that they can intervene in time?
The answer is unfortunately no.
There are no detectable symptoms of SIDS, infants who die from this syndrome do not seem to suffer from any form of pain or show any physical evidence.
Some researchers have tried to hazard a correlation between flu-like respiratory symptoms, but the issue is still highly debated.
Although there are no certain causes or symptoms, there is evidence of the existence of behaviours and conditions that may be factors that increase the risk of SIDS, and others that are, on the contrary, protective factors (lowering the risk).
Factors that increase the risk of cot death in infants
Faced with the impossibility of determining an unambiguous cause, epidemiological studies have been carried out which have found the existence of some preventable and some non-preventable risk factors; none of these, however, is a specific cause of SIDS.
The requirement for a combination of factors including an underlying genetic susceptibility, a specific time frame in the child’s development and an environmental stressor has been proposed.
These environmental stresses may include sleeping on the stomach or on the side, overheating and exposure to tobacco smoke.
Accidental suffocation during bed sharing (also known as co-sleeping) or suffocation from soft objects may also play a role.
Another non-modifiable risk factor is 39 weeks gestation.
Other causes include infections, genetic disorders and heart problems.
While child abuse in the form of intentional suffocation may be misdiagnosed as SIDS, this is believed to account for less than 5% of cases.
Differences in frequency have been found in correlation with gender and age of the infant, ethnic origin, cultural and economic level of the parents.
Methods that completely reduce the risk of SIDS are not currently available, although there are several interventions that can significantly reduce the incidence of SIDS in children.
Numerous studies show that one of the main factors is a sleeping position other than supine (the risk is much higher if the infant sleeps on its stomach, or on its side).
It is therefore strongly recommended to always put the baby to sleep on its back (back against the bed, belly up).
It is estimated that if the safer habit of having babies sleep supine (on their stomachs) instead of prone (on their stomachs) had become widespread as early as the 1970s, i.e. when the first scientific and clinical evidence on the subject was available, the lives of about 50,000 babies in Western countries alone could have been saved.
Modifiable and/or preventable risk factors for infant cot death
Preventable risk conditions for SIDS include:
- cigarette smoking in the home
- mother smoking during pregnancy (similarly with stop-smoking patches);
- inadequate prenatal nutrition and care;
- alcohol and heroin use;
- excessively high room temperature;
- excessive clothing;
- excessive use of blankets;
- respiratory infections;
- sleeping position other than supine;
- long QT interval (detectable by electrocardiogram).
Non-modifiable risk factors
- age of the infant (younger than 5 months)
- premature birth;
- winter season.
Parental bed sharing
Parental bed sharing appears to increase the incidence of the syndrome, particularly if:
- one or both parents are smokers
- one or both parents use alcohol, drugs, medication;
- one or both parents are of imposing weight and build;
- one or both parents are ‘heavy sleepers’;
- one or both parents sleep on armchairs, sofas, soft surfaces in which there is the possibility of ‘sinking’.
Passive and tertiary smoking
Second-hand smoke is correlated with the syndrome: children who die from SIDS tend to have higher concentrations of nicotine and cotinine (indicating chronic exposure to second-hand smoke) in their lungs than children who die from other causes.
Even smoking outside the home, however, exposes the child to high amounts of tertiary smoke, so in order to completely eliminate the risk factor, it is absolutely advisable for parents to stop smoking altogether, which will improve the health of all members of the household and also lower the risk of the child smoking as an adult.
Cot death and vaccines: is there a link?
Vaccines are NOT a risk factor for SIDS. On the contrary, according to some studies, in some cases vaccines have a protective effect against SIDS: the diphtheria-tetanus-pertussis vaccination, for example, is correlated with a reduction in SIDS.
Cot death and cardiac arrhythmias
Alongside numerous studies on the pathogenesis of SIDS, those dealing with genetically based cardiac arrhythmias, i.e. channelopathies and especially long QT syndrome, are becoming increasingly important.
Although in more limited numbers some cases of SIDS have been associated with Brugada syndrome, short QT syndrome and catecholaminergic polymorphic ventricular tachycardia.
Prevention of infant cot death
In view of the risk factors, there are some recommendations to reduce the risk of SIDS:
- the baby should sleep on its stomach (supine);
- there should be no smoking in the environment where he or she stays or sleeps and in the home;
- the environment where he sleeps must not be too hot, (the microclimate of the room is optimal when the temperature is between 18°C and 20°C and when a good change of air allows the humidity to be around 50%) he must not be overly covered and he must sleep far from sources of heat;
- in case of fever, the child should be covered less;
- it is recommended that the baby sleep in its parents’ room in its cot and not in its parents’ bed;
- the use of dummies is now considered a risk mitigating factor.
How to organise the cradle to lower the risk of infant cot death?
To lower the risk of SIDS, no objects that might restrict the baby’s breathing (e.g. puppets, stuffed animals, pillows, crumpled sheets) should be present in the cradle.
The sheet should not be placed over the baby’s head but should only cover up to the chest and the arms should be uncovered so that their movement does not cause the sheet to cover the head and airways.
Sucking and cot death of the infant
A 2005 study showed that dummy use reduced the risk of the syndrome by 90%.
This appears to be due to the fact that the mesencephalic nucleus of the trigeminal nerve, activated by dummy use, activates Arousal through the activation of the reticular formation.
This allows control of the infant’s vital functions (heart rate, respiration, pH and blood temperature), which otherwise, especially in immature infants, might fail under conditions of minimal environmental stimulus (in sleep).
The effector of these functions is the neurotransmitter Glutamate produced, precisely, by the mesencephalic nucleus of the trigeminal on stimulation, in this case, of the dummy.
Near miss SIDS
If rescued promptly, some SIDS infants can be resuscitated and in this case we speak of ‘near miss SIDS’, however, there is still a very high risk of more or less severe permanent brain injury due to anoxia with possible disability.