What is Sudden Infant Death Syndrome (SIDS)?
Sudden Infant Death Syndrome (SIDS) is when a baby less than a year old dies suddenly and without clear explanation. Even after going through the baby’s medical history, investigating the cause of death, and doing a full autopsy, no clear cause of death can be found. SIDS often happens while the baby is sleeping and is the main cause of death for babies between one to twelve months old in the United States. Due to some inconsistency in using “SIDS” to describe these kinds of deaths, the term “Sudden Unexpected Infant Death” or “SUID” has been introduced. SUID is a broader term that includes SIDS, death from accidental suffocation or lack of oxygen, and deaths where the cause is uncertain.
What Causes Sudden Infant Death Syndrome (SIDS)?
The cause of Sudden Infant Death Syndrome (SIDS), also known as crib death, is not completely understood. Research suggests that it might be caused by a baby’s inability to respond properly to conditions where there’s too little oxygen (hypoxemia) or too much carbon dioxide (hypercarbia) in the body, along with a mix of other internal and external factors.
The most effective way to prevent SIDS that we know of is placing a baby to sleep on their back, also known as the supine sleeping position. Promoting this method of sleeping has greatly reduced the number of SIDS deaths. In fact, countries that specifically promote back sleeping have seen significant decreases in SIDS cases.
For instance, SIDS cases decreased by over 50% in the United States when doctors began advising parents to put their babies to sleep on their backs. After the American Academy of Pediatrics (AAP) recommended back sleeping in 1992, the number of SIDS cases fell dramatically. From 1992 to 2001, the rate of SIDS deaths went from 1.2 to 0.56 deaths per 1000 live births. During this time, the percentage of babies sleeping on their backs rose from 13% to 72%.
Risk Factors and Frequency for Sudden Infant Death Syndrome (SIDS)
The Centers for Disease Control and Prevention (CDC) states that in 2017, 35.4 out of 100,000 live births in the U.S. resulted in Sudden Infant Death Syndrome (SIDS). Previously, before efforts were made to reduce SIDS, the death rates varied across different countries and ethnic communities. For instance, among Asian communities in the U.S. and Bangladeshis in the U.K., the death rate was as low as 0.3 in 1000 live births, whereas it was as high as 7.4 in 100 live births among the Maori community in New Zealand. Cultural norms, childcare practices, and socioeconomic status often accounted for this variation.
In the U.S., the CDC reports revealed similar variations across different racial and ethnic groups. The peak occurrence of SIDS is between 2 and 4 months of age, and 90% of the cases occur before the age of six months.
Evidence suggests that in most SIDS cases (about 95%) there was at least one risk factor present, and in 78% of the cases, there were at least two risk factors. Some identified risk factors include sleeping face down, sleeping on soft surfaces, sleeping with soft objects, co-sleeping with parents, maternal smoking during pregnancy, having a mother younger than 20 years, late or no prenatal care, premature birth, low birth weight, lack of breastfeeding, and overheating. Maternal drug use and exposure to tobacco smoke were also associated with a higher incidence of SIDS. However, being exposed to smoke doesn’t necessarily mean it’s a primary cause of SIDS.
On the other hand, a history of apnea and upper respiratory infection aren’t considered to be risk factors for SIDS. Some controversial studies suggest that parents sleeping in the same room (but in separate beds), breastfeeding, using pacifiers, using fans, and vaccinations might act as protective factors against SIDS.
Additionally, siblings of infants who died from SIDS have a 5-6 times higher risk of dying from it as well. However, not all sibling deaths can be attributed to SIDS as some were caused by metabolic disorders, abuse, and malnutrition. Twins are twice as likely to die from SIDS, regardless of whether they were born prematurely, at term, or weighing more than 3kg at birth.
Signs and Symptoms of Sudden Infant Death Syndrome (SIDS)
Sudden Infant Death Syndrome, or SIDS, often results in infants being found deceased during the morning hours. A major percentage of these sad events occur between midnight and 6 o’clock in the morning. It’s also not uncommon for these infants to be discovered with their heads covered by their bedding. Sometimes, these babies might have a liquid that appears to be tinged with blood in their noses, but other than that, they physically look normal on the outside.
Testing for Sudden Infant Death Syndrome (SIDS)
Sudden Infant Death Syndrome (SIDS) is a condition that causes sudden and unexpected death in infants, typically during sleep. The exact cause of SIDS is not known. However, diagnosing SIDS requires a thorough investigation, which includes reviewing the baby’s medical history, an assessment of the scene where the death occurred, and a full autopsy. This investigation process generally follows international guidelines and protocols. Unfortunately, no national protocol is available in the United States, as the laws around investigations of unexpected deaths vary by state.
The first part of the investigation is a detailed interview with caregivers. This is usually done by professionals who are sensitive to the cultural backgrounds of the caregivers. The focus is on open-ended and non-blaming questions. The objective is to gather information about any risk factors present, including the baby’s sleeping position, whether the baby was sharing a bed with anyone, and the baby’s medical history including any prenatal history.
Then, an autopsy is carried out. This is a comprehensive examination of the baby’s body after death. Despite performing autopsies, it’s important to note that the specific cause of death is only found in about 15% of SIDS cases. The autopsy involves both external and internal inspection of the body, X-rays, testing for infections, toxic substances, and any anomalies in the baby’s metabolism. Additionally, tests are performed to screen for inherited disorders in the baby’s genes.
Further to the autopsy, metabolic screening is conducted. This includes specific tests such as plasma acylcarnitine profile, quantitative plasma carnitine levels, quantitative plasma amino acid analysis, qualitative urine organic acid analysis, as well as plasma lactate and pyruvate.
Another important part of the investigation is a detailed examination of the scene where the death occurred. This should ideally be done by first responders, who should observe and record various details even before starting resuscitation efforts. These details include the room temperature, the baby’s first recorded temperature, the heating or ventilation system in the home, location of the baby, condition and quality of the bed or crib, the baby’s clothing and the presence of any bedding or soft objects which could potentially block the baby’s airway, any marks on the baby’s body, and the reactions of the caregivers. The goal is to collect as much information as possible to give the best chance of understanding what may have led to the baby’s death.
Treatment Options for Sudden Infant Death Syndrome (SIDS)
If a baby’s death raises suspicions of Sudden Infant Death Syndrome (SIDS), a thorough inspection needs to be conducted as per guidelines. During this challenging time, it’s vital to comfort and teach parents or caregivers about SIDS.
If the investigation reveals a genetic cause, the family may need to speak with a genetic counselor. This professional can help them understand the nature of the genetic issue and its implications for future pregnancies.
Prevention of SIDS is often achieved through awareness and understanding of the risk factors. This knowledge allows parents and caregivers to create safer sleeping environments for their babies. However, using devices to monitor a baby’s heart and breathing is not recommended for preventing SIDS.
What else can Sudden Infant Death Syndrome (SIDS) be?
There are several conditions that can seem very similar to Sudden Infant Death Syndrome (SIDS). These include:
- Aspiration (inhaling food, drink, vomit, or saliva into the lungs)
- Suffocation
- Severe allergic reactions (anaphylaxis)
- Poisoning
- Child abuse that results in death
- Injuries (trauma)
- Overheating (hyperthermia)
- Metabolic disorders (problems with the body’s chemical reactions)
- Breathing and lung issues, like cystic fibrosis
- Liver inflammation (hepatitis)
- Pancreas inflammation (pancreatitis)
- Brain inflammation (encephalitis)
- Bleeding caused by abnormal blood vessels (AV malformation with hemorrhage)
- Excessive hormones caused by enlarged adrenal glands (congenital adrenal hyperplasia)
- High blood pressure in the lungs (pulmonary hypertension)
- Sickle cell crisis (a painful episode common in people with sickle cell disease)
- Heart problems, including birth defects
- Sepsis (a life-threatening infection)
- Infections like bronchiolitis, pneumonia, tracheobronchitis, pyelonephritis, and enterocolitis with Salmonella, Shigella, or E. coli bacteria
Child abuse that results in death and certain metabolic diseases are of special concern because they can impact other family members as well. Child abuse can cause up to 5% of cases that are initially thought to be SIDS. Abuse could lead to injury, choked breathing, or poisoning. Autopsies can’t always tell the difference between accidental choking, purposeful choking, or SIDS, but some warning signs of abuse are unexplained drops in blood oxygen levels, stop in breathing, or life-threatening events happening when only one person is caring for the child.
Metabolic diseases weren’t found to be more common in sudden infant deaths, compared to the general population. These conditions can be suggested by a past unexplained death of a sibling, a history in the family of certain conditions, or signs such as failing to gain weight, vomiting, low blood sugar, low muscle tone, trouble controlling breathing, serious infections, or high levels of liver enzymes. The defects often affect how the body breaks down fatty acids and certain amino acids, or how it processes waste products. defects in fatty acid metabolism, specifically in an enzyme called MCAD, are often found in sudden death cases. Autopsies can sometimes identify abnormal by-products in the body as a result of metabolic diseases.
Preventing Sudden Infant Death Syndrome (SIDS)
Doctors strongly advise a few safety measures to prevent Sudden Infant Death Syndrome (SIDS), a sudden and unexplained death of a baby less than 1 year old. During pregnancy, one should avoid consuming alcohol and using illegal drugs. After birth, babies should always be put to sleep on their backs, in their own crib that is placed in the same room as caregivers. The crib should have a firm, flat surface and be safety-approved.
Things such as blankets, pillows, toys, and bumper pads should not be in the crib. It’s also critical to ensure the baby’s head is uncovered so they don’t get too hot. Second-hand smoke can harm the baby, so if a person smokes, they should change clothes and wash their hair before contact with the baby.
Infants and caregivers can also benefit from learning how to use a pacifier at bedtime. But remember, do not ever prop bottles in the baby’s mouth! Breastfeeding and immunizations are likewise beneficial for the baby.
Unfortunately, despite knowing these safety measures, not everyone follows them. In 2015, about 80% of people in the U.S. were reported to be following these guidelines. Even though this rate increased to 93% in 2019, it still didn’t reach the targeted level. Some parents didn’t even recall hearing about or weren’t following properly the recommendations regarding avoiding soft objects near the crib (85%), using safe sleeping surfaces (84%), or sharing a room without sharing a bed (50%).
