2,300 children die every year in the US because of Sudden Infant Death Syndrome (SIDS). However, many infants do not exhibit any SIDS symptoms. Read more at Meri Sehat.

Sudden Infant Death Syndrome (SIDS)

Humza Khizer

Overview

SIDS or sudden infant death syndrome is the sudden and unexpected passing, usually during sleep, of an otherwise healthy baby less than a year old. It is also called Sudden unexpected infant death (SUID)&nbsp; or &lsquo;crib death&rsquo; as newborns frequently pass away in their cribs<a href="#accordion">[1]</a>. Despite years of research, the cause of sudden infant death syndrome (SIDS) remains unknown.

&nbsp;

Every year, over 3,400 babies in the US pass away abruptly and unexpectedly<a href="#accordion">[2]</a>. Approximately 90 percent of these deaths occur within the first 6 months, with a peak between 1-4 months<a href="#accordion">[3]</a>. Usually, death comes during sleep and is very unpredictable and sudden, which is alarming since most babies are reported to be healthy before their death.

A thorough investigation is done of the death scene and environmental factors. Moreover, along with an autopsy, a history of the baby and caregivers is taken. If the right precautions are taken, the chances of SIDS can be reduced significantly<a href="#accordion">[2][3]</a>. 
&nbsp;

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There are no types of SIDS. 
&nbsp;

Signs and Symptoms

Unfortunately, there are no warning signs of SIDS. 
&nbsp;

Causes

Some factors make a child more vulnerable to SIDS. These are as follows: 
&nbsp;

<h5>Physical Factors:</h5>

<ul>
	<li>Defect In The Brain: Insufficient maturation of a portion of the infant&rsquo;s brain that controls arousal and breathing means the infant is more likely to die of SIDS.</li>
	<li>Low Birth Weight: Infants born prematurely or part of multiple births have an increased risk of an underdeveloped brain, which means they have reduced control over heart rate and breathing.</li>
	<li>Lung Infection: Several newborns that died of SIDS had a recent cold which could have caused breathing problems. 
	&nbsp;</li>
</ul>

<h5>Sleep Environmental Factors:</h5>

Certain objects present in the baby&rsquo;s cot and the position of the baby while sleeping can combine with physical problems to increase the risk of SIDS. For instance:

<ul>
	<li>Sleeping On The Side Or Stomach: In these positions, babies might have a tougher time breathing than when placed on their backs.</li>
	<li>Bed-Sharing: The risk of SIDS is lowered if the baby sleeps in the same room as the parents. However, the risk increases if a bed is shared with the infant by his parents or siblings.</li>
	<li>Overheating: If a baby is too warm while sleeping, it can increase the risk of SIDS.</li>
	<li>Sleeping On Soft Surfaces: An infant&#39;s airway can become blocked if they sleep on a fluffy, soft mattress or a waterbed. 
	&nbsp;</li>
</ul>

Diagnosis

To make a diagnosis, a thorough investigation is required

<ul>
	<li>History: Caretakers are interviewed using open-ended questions that do not have an accusatory tone. They are questioned on certain risk factors such as the infant&#39;s sleeping position, co-sleeping, and medical history. 
	&nbsp;</li>
	<li>Autopsy: Injuries, congenital abnormalities, metabolic defects and infections may come to light with an autopsy. The procedure helps identify the cause of only 15% of SIDS deaths4. Internal and external examination, radiologic evaluation, microbiology, toxicology, and laboratory studies are all part of an autopsy. Laboratory evaluation includes electrolytes, metabolism errors screening, and genetic disorders screening. 
	&nbsp;</li>
	<li>Metabolic Screening: The labs recommended are quantitative plasma carnitine levels, plasma acylcarnitine profile, quantitative plasma amino acid analysis, qualitative urine organic analysis, and plasma lactate and pyruvate. 
	&nbsp;</li>
	<li>Investigation Of The Death Scene: Before starting to revive the patient, first aid personnel should be taught to visually survey the scene as they arrive on the site. The following details should be noted: the room&#39;s temperature, the baby&#39;s first temperature, the type of heating or ventilation system being used in the house, the baby&#39;s location, the crib&#39;s condition and quality, the quantity and placement of the baby&#39;s clothing, the presence or absence of bedding or other soft objects in the baby&#39;s sleeping area, the presence or absence of marks on the baby&#39;s body, and the caregivers&#39; reactions. 
	&nbsp;</li>
</ul>

<h5>Differential Diagnosis</h5>

The following disorder can mimic SIDS:

<ul>
	<li>Asphyxiation</li>
	<li>Aspiration</li>
	<li>Fatal child abuse</li>
	<li>Anaphylaxis</li>
	<li>Hyperthermia</li>
	<li><a href="https://merisehat.pk/disease/cystic-fibrosis">Cystic fibrosis</a></li>
	<li>Metabolic disorders</li>
	<li>Encephalitis</li>
	<li>Pancreatitis</li>
	<li>AV malformation with haemorrhage</li>
	<li><a href="https://merisehat.pk/disease/pulmonary-hypertension">Pulmonary hypertension</a></li>
	<li>Congenital adrenal hyperplasia</li>
	<li>Sickle cell crisis</li>
	<li><a href="https://merisehat.pk/disease/congenital-heart-diseases">Congenital heart disease</a></li>
	<li>Myocarditis</li>
	<li>Sepsis and infections include bronchiolitis, <a href="https://merisehat.pk/disease/pneumonia">pneumonia</a>, tracheobronchitis, pyelonephritis, and enterocolitis with salmonella, shigella, or Escherichia coli. 
	&nbsp;</li>
</ul>

Fatal child abuse should be given immediate attention as other family members can also be potential victims. 1-5% of cases of SIDS are accounted for by child abuse4. The most frequent mechanism is a closed head injury, but other possible causes include trauma, intentional suffocation, or poisoning. An autopsy cannot distinguish between SIDS, intentional asphyxia, or accidental asphyxia. However, the characteristics that point to fatal child abuse include recurrent episodes of unexplained cyanosis and&nbsp;apnea, that&nbsp;happen in the presence of a single caregiver, the simultaneous death of twins, previously unsolved deaths of siblings, and the unexplained death of a child older than six months<a href="#accordion">[4]</a>. 
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Treatment

There is currently no treatment for SIDS as the definite cause is unknown. 
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Even though SIDS can affect any infant, research has given us several factors that might increase the risk. They are as follows: 
&nbsp;

<ul>
	<li>Age: the most vulnerable age for SIDS is between 2-4 months</li>
	<li>Sex: boys have a slightly higher risk of death from SIDS</li>
	<li>Race: for incomprehensible reasons, babies from ethnicities other than white are more likely to develop SIDS</li>
	<li>Family History: infants having siblings or cousins who have died from SIDS are at a higher risk of SIDS themselves</li>
	<li>Passive Smoking: infants living with smokers show a higher risk of SIDS</li>
	<li>Premature Baby: early birth and low birth weight both increase an infant&#39;s risk of SIDS</li>
	<li>Temperature: overheating while sleeping increases the risk</li>
	<li>Sleeping On soft Surfaces: babies who sleep on surfaces that are too soft or have soft blankets in their cribs along with bumper pads</li>
	<li>Co-Sleeping: the risk increases if a baby sleeps with parents or siblings</li>
	<li>Stomach Sleeping: babies who sleep on their stomachs or sides are at a higher risk because<a href="#accordion">[5]</a>,</li>
</ul>

<ol>
	<li>It may block the airway</li>
	<li>The baby could be rebreathing their own exhaled air which happens due to soft bedding, blanket, stuffed toys or pillow near their face. This causes a deficiency of oxygen in their body and an increase in carbon dioxide. The part of the brain that signals the baby to wake up due to lack of oxygen can have a problem and that signal can fail, causing the baby to stay asleep instead of wake up and cry. 
	&nbsp;</li>
</ol>

<h5>Maternal Risk Factors: </h5>

The presence of the following factors during pregnancy increases the risk of SIDS in infants.

<ul>
	<li>Maternal age below 20 years</li>
	<li>Smoking</li>
	<li>Alcohol or drug use</li>
	<li>Insufficient prenatal care<a href="#accordion">[1][3]</a>. 
	&nbsp;</li>
</ul>

Even though there are no guaranteed methods to prevent SIDS, these measures can help the infant sleep safer:

<ul>
	<li>Back To Sleep: Place your baby on their back when putting them to sleep for the first year of their life. Make sure if anyone else is putting them to bed, they are aware of placing the baby on the back and not the side or stomach. Only give the baby tummy time in your supervision and while they are awake, or able to roll over on their own. Advise the childcare providers or sitters not to calm a crying baby by putting them on their stomachs 
	&nbsp;</li>
	<li>KeepThe Crib As Light As Possible: Keep loose sheets and bedding away from the crib and use a firm mattress with a fitted sheet. No toys, pillows or heavy blankets are to be placed in the crib. Do not place bumper pads in the crib as they can be a strangulation or suffocation hazard. 
	&nbsp;</li>
	<li>Do Not Let Your Baby Get Overheated: Dress your baby to room temperature instead of covering them with blankets. A sleep sack can be used which keeps the baby&rsquo;s hands free and leaves no extra material that can reach and cover the face. Look out for signs of overheating like sweating or feeling hot on the touch. 
	&nbsp;</li>
	<li>Share The Room But Not The Bed: Ideally, you should keep the baby&rsquo;s crib in your room for the first 6-12 months. Bed sharing is dangerous as the parent can roll over and suffocate the baby, or they can be suffocated by blankets or the headboard slats. 
	&nbsp;</li>
	<li>Breastfeed The Baby: For at least 6 months, breastfeed the baby as it reduces the risk of SIDS. 
	&nbsp;</li>
	<li>Do Not Use Any Commercial Product Claiming To Reduce SIDS: Use of sleep positioners (such as wedges or incliners) or monitors that can track a baby&#39;s breathing pattern are examples of products or equipment that make the claim that they can reduce the risk of SIDS. This cannot truly be done by any known products. 
	&nbsp;</li>
	<li>Provide The Baby With A&nbsp;Pacifier: Give the baby a pacifier at bedtime, but once they are asleep and spit the pacifier out, there is no need to place it back into the mouth. If breastfeeding, wait for 3-4 weeks after birth to introduce a pacifier but if your baby refuses it then there is no need to force it. 
	&nbsp;</li>
	<li>Vaccinate Your Baby: There is no evidence that vaccination increases the risk of SIDS. Some evidence shows that vaccinations can help to prevent SIDS. 
	&nbsp;</li>
	<li>Prenatal Care: Get regular and early prenatal care. 
	&nbsp;</li>
	<li>Do Not Smoke: Infants of smoker mothers show a higher risk of SIDS, especially if that parent co-slept with them. 
	&nbsp;</li>
	<li>Do Not Consume Alcohol Or Drugs: Parents who use drugs and alcohol should not share a bed with their baby. 
	&nbsp;</li>
	<li>Do Not Let Your Baby Sleep In Products That Are Not Designed For Sleeping Babies: These products include feeding pillows, car seats, or infant loungers<a href="#accordion">[1][5]</a>. 
	&nbsp;</li>
</ul>

A recent Australian study analyzed blood samples from more than 600 healthy newborns as part of the newborn screening program. The study measured butyrylcholinesterase (BChE) activity in newborns. BChE is an enzyme that helps in the hydrolysis of the neurotransmitter acetylcholine. Thus, modulating cholinergic activity and enabling the brain to communicate waking-up instructions.

As per the results, 26 newborns died from SIDS, while 41 died of another cause. 9 out of the 10 infants who died from SIDS, had reduced levels of the enzyme BChE. The reduced enzyme levels support the theory that some infants die from SIDS due to the inability of the brain to send &lsquo;wake-up&rsquo; signals during harmful situations. This is the first time researchers have identified a biochemical marker specifically for SIDS. However, due to the study&rsquo;s small sample size and several limitations, it is unclear whether testing for BChE is effective for SIDS<a href="#accordion">[6]</a>. 
&nbsp;

Key Points

<ul>
	<li>Sudden infant death syndrome, or SIDS, is the unexpected passing of a seemingly healthy baby below the age of 1 year, usually while sleeping.</li>
	<li>90 % of deaths in SIDS occur within the first 6 months, with a peak between 1-4 months.</li>
	<li>Environmental factors for SIDs include bed-sharing, sleeping on the side or stomach, having soft bedding and overheating. Physical factors contributing to SIDS are low birth weight, neurological defects, and decreased lung infection.</li>
	<li>Diagnosis is based on history, autopsy, metabolic screening, and investigation of the death scene.</li>
	<li>One of the highlighted differential diagnoses of SIDS is fatal child abuse which turns out to be 1-5% of cases diagnosed as SIDS.</li>
	<li>Age, sex, race, family history, passive smoking, premature birth, overheating, sleeping on the stomach or sides, co-sleeping, and sleeping on soft surfaces are all risk factors for SIDS</li>
	<li>Maternal risk factors include being below 20, smoking, insufficient prenatal care, and use of alcohol or drugs.</li>
	<li>Preventive measures such as placing the baby on the back to sleep, keeping the crib as light as possible, not letting the baby overheat, sharing the room with your baby but not the bed, breastfeeding the baby, providing the baby with a pacifier, vaccination and &nbsp;prenatal care etc. can help prevent SIDS</li>
	<li>The latest research has found that babies that die of SIDS have reduced levels of the enzyme butyrylcholinesterase (BChE). The enzyme is responsible for helping the brain send &lsquo;wake-up&rsquo; signals to the baby in dangerous situations. 
	&nbsp;</li>
</ul>

[1] Sudden infant death syndrome (SIDS). Mayo Clinic.

[2] About sids and suid. Centers for Disease Control and Prevention.

[3] Paterson ~ D. Sudden infant death syndrome (SIDS). Sudden Infant Death Syndrome SIDS | Boston Children's Hospital

[4] NCBI Bookshelf.

[5] Ben-Joseph EP, ed. Sudden infant death syndrome (SIDS) (for parents) - nemours kidshealth. KidsHealth

[6] Harrington CT, Hafid NA, Waters KA. Butyrylcholinesterase is a potential biomarker for sudden infant death syndrome. eBioMedicine. 2022;80:104041. doi:10.1016/j.ebiom.2022.104041

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