Sudden Infant Death Syndrome (SIDS) is the sudden death of a healthy baby in the first year of life. SIDS is the leading cause of post-neonatal mortality in the United States (1 in 2,000 infants).
SIDS is the diagnosis made by exclusion, that is, if after investigation and autopsy no other cause of death is established. Although the cause of SIDS is by definition unknown, it is crystal clear that vaccines have nothing to do with it, exactly as is the case with autism.
In infants whose mothers smoked during pregnancy, the risk of death was 4 times higher compared to non-smoking mothers. SIDS risk was also increased if mothers continued to smoke after birth. The more mother smoked, the higher was the SIDS prevalence. Father's smoking also increased the risk of SIDS. More: 
In infants of alcoholic mothers, the prevalence of SIDS was increased by 7-8-fold, and the risk of death from other causes was 2.3 times higher. More: 
Sleep on the stomach is associated with a 3-9-fold increased prevalence of SIDS.
Some parents believe that the baby is uncomfortable sleeping on his back, or that it does not sleep well in this position. The American Academy of Pediatrics argues that indeed, a baby sleeping on his stomach sleeps longer, but it’s normal that the baby wakes up often, and this does not mean that the quality of sleep is lower. Also, per AAP the baby’s ability to sleep for a long time may not be physiologically beneficial.
Sleeping in a separate room is associated with a ten-fold risk of SIDS. Sleeping with parents in the same bed (especially on the couch) is also associated with a ten-fold risk of SIDS, but only if parents smoke or drink. Parents of 80-90% of babies who die from SIDS smoke.
Clothing that is too warm and excessive wrapping are associated with an 18-fold risk of SIDS. The risk of SIDS increases during winter months. Blankets and pillows also increase the risk.
Other risk factors include drug abuse, low socioeconomic status, lower maternal education level and low birth weight. Infant boys are 30%–50% more likely than girls to be affected.
Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis.
Meta-analysis of 18 studies. In infants who received any amount of breast milk for any duration, the incidence of SIDS was 60% lower. For exclusive breastfeeding the incidence of SIDS was 73% lower.
Breastfeeding does not reduce the risk of SIDS in smoking mothers.
The use of pacifiers is associated with a reduced risk of SIDS. However, it is associated with an increased risk of otitis media and gastrointestinal infections.
Diphtheria-tetanus-pertussis immunization and sudden infant death syndrome.
Am J Public Health
The SIDS mortality rate during first 3 days after DTP vaccination was 7.3 times higher than during the 30 days after vaccination. The mortality rate decreased gradually over the four weeks after vaccination. The mortality rate in the first month after DTP vaccination was 2.9 times higher than the mortality rate post this time period.
However, the mortality rate among non-vaccinated with DTP was 6.5 times higher than among vaccinated. This conclusion was made based on six non-vaccinated infants. Mothers of 4 of them were single, 3 were unemployed, 2 received welfare and at least in one of the families physical violence was observed. The authors note that SIDS mortality rate has not changed in the UK after the vaccination refusal became common and the subsequent epidemic of pertussis, and therefore it is unlikely that vaccination against pertussis protects against SIDS.
Possible temporal association between diphtheria-tetanus toxoid-pertussis vaccination and sudden infant death syndrome.
Pediatr Infect Dis
DTP vaccination and doctor visits are associated with SIDS in Los Angeles. 6 out of 27 infants died within 24 hours of the vaccination, and 17 died in the first week after the vaccination.
This study was criticized because, in the reviewer's opinion, it does not take into account that the period of increased risk of dying from SIDS coincides with the period when infants are vaccinated and then falls sharply. It may therefore have been a coincidence that infants died more often on the first day and the first week after vaccination.
Do immunisations reduce the risk for SIDS? A meta-analysis.
The highest rate of SIDS occurs between the second and fifth months of life. That's when infants get their first vaccinations. This temporary link begs the question of whether vaccination is not a risk factor for SIDS.
The authors performed a meta-analysis of 9 studies and found that vaccination was associated with reduction of SIDS risk by half. They notice that this may be due to the "healthy vaccinated effect", as vaccination is generally avoided during illness. All the included studies were case-controlled, as there are no randomized studies on the subject.
Confounding in Studies of Adverse Reactions to Vaccines.
Am J Epidemiol
Most studies have found that vaccinated infants die less frequently from SIDS than the non-vaccinated. Moreover, there are studies showing that the risk of SIDS decreases immediately after vaccination.
This happens because the risk factors for SIDS are the same as medical reasons for avoiding vaccinations. In addition, usually the children that are being vaccinated are healthy, and the risk of sudden death for them is lower than in unhealthy ones. Studies do not take these factors into account, leading to underestimation of the real risks associated with vaccination.
It is also reported that the largest study of encephalopathy in the UK found a significant correlation between DTP (but not DT) vaccine and encephalopathy over the next 7 days, and between measles vaccination and encephalopathy over the next 7-14 days.
Vaccination and unexplained sudden death risk in Taiwanese infants.
Pharmacoepidemiol Drug Saf
In March 1992, 8 infants in Taiwan died within 36 hours of their DTP vaccination. Seven of them received vaccines from the same lot (which accounted for 58% of the vaccines used at that time), which prompted the authorities to suspend the vaccination of that lot.
The authors analyzed the cases of SIDS in Taiwan between 1996 and 2013 and concluded that the risk of sudden death after DTP is 60% higher in girls within two days of vaccination. The authors conclude that the vaccine probably only accelerated the deaths of these girls for a couple of days, and they were already destined to die from SIDS, just a little later than they actually did.
Deaths reported after pentavalent vaccine compared with death reported after diphtheria-tetanus-pertussis vaccine: an exploratory analysis.
Med J DY Patil Vidyapeeth
In 2011, India began using pentavalent vaccines (DTP-Hib-HepB).instead of trivalent ones (DTP). This made possible the comparison between post-vaccination mortality rates of both vaccines. The authors have analyzed data on 45 million infants. The mortality rate within 72 hours after the pentavalent vaccine was twice as high as after the trivalent vaccine (4.8 vs. 9.6 per million). The authors note that not all post-vaccination deaths occur within 72 hours, so the post-vaccination mortality rate in this study is underestimated.
Mortality varied considerably between provinces, which was probably due to the fact that some provinces had poor record keeping. If considering the average rates, the vaccine will result in 122 additional deaths within 72 hours (per 26 million infants born per year). But if we consider the provinces with the most accurate records, the vaccine will result in 7020-8190 deaths. (That's about 1 per 3,200 vaccinated. And if we take into account that only additional deaths on top of the DTP-associated ones are considered, and that DTP itself probably also leads to death, then the total mortality rates associated with the pentavalent vaccine will be 1 in 1600 vaccinated. And that applies just to the first 72 hours).
Most of these deaths cases had been examined by experts, and not in a single case was vaccination recognized as the cause of death. According to the new WHO criteria, only adverse events that had already been published in scientific articles may be recognized as vaccination adverse effects. Both the DTP insert and the pentavalent vaccine insert do not list death as a possible adverse effect, so it is of no surprise that no investigated death cases have been recognized as caused by vaccines.
The pentavalent vaccine was also introduced in Sri Lanka, Bhutan and Viet Nam, and in all these countries it was associated with adverse effects, including unexplained deaths. There have been sporadic deaths cases shortly after this vaccination in India as well, including the death of two infants the day after the vaccination. WHO had investigated these cases and concluded that they are unlikely to be related to vaccination. 3 deaths in Sri Lanka were initially recognized as likely caused by the vaccine. WHO then revised the algorithm for determining vaccine adverse effects in 2013, and these deaths were reclassified as unrelated to vaccination. More:  
Deaths following pentavalent vaccine and the revised AEFI classification.
Indian J Med Ethics
According to the new WHO algorithm, deaths that occurred after the vaccine was certified cannot be classified as vaccine-related if no statistically significant increase in mortality was found in small clinical studies. If the vaccine was associated with a significant increase in mortality in clinical trials, it would not be certified. After the vaccine is certified, all the death cases are being marked just as coincidental.
Also, according to the new protocol, if, for example, a child with a heart condition develops heart decompensation after vaccination, then the decompensation will not be considered to be causally related to the vaccination, although the vaccination contributed to it.
The implications of this new classification are shown in the analysis of serious adverse event cases in India. Of the 132 infants, 78 were hospitalized and 54 died. In 47% of those who survived, the adverse events were recognized as related to the vaccine, while no death case was recognized as such.
The author concludes that the protocol should be reviewed urgently and that the focus should be on the safety of children and not on safety for vaccines.
AEFI and the pentavalent vaccine: looking for a composite picture.
Indian J Med Ethics
In Viet Nam, the usage of the pentavalent vaccine had ceased in 2013, after death of 12 infants and 9 cases of non-lethal serious adverse events. WHO concluded that not-lethal serious cases might be associated with vaccination, but fatalities cannot. Because no one has ever died from that vaccine.
These infants were healthy before the vaccination, but within a few hours after they started to cry, experience convulsions and difficulty breathing, and passed away in a short time.
In Bhutan, the vaccination program was halted after four death cases. WHO persuaded Bhutan to resume the program, as the deaths were probably coincidental, due to viral meningoencephalitis. After that, four more infants died. Vaccination was cancelled in Bhutan second time, and no cases of "meningoencephalitis" had been reported in the following year.
Three infants died in Pakistan, one within half an hour and two within 12-14 hours after vaccination. It was determined that those who died after sunset died from SIDS, and that the cause of death of the infant who died within half an hour is "unclear". The vaccine remained at no fault. These deaths were not mentioned in the WHO report.
In Sri Lanka, five infants died, and after that the vaccination was stopped. Fourteen more infants died after it resumed.
The incidence of invasive H.influenzae infection in India is very low. 350 children are expected to die from it in the next five years. The vaccine that claims to protect against Hib will kill 3125 children.
The vaccine insert does not mention infant deaths, either in India or elsewhere. A total of at least 70 deaths in 5 countries were associated with different brands of pentavalent vaccine.
It is reported that more than 10,000 children in India have died due to vaccines adverse events in the past 10 years.
Evidence of Increase in Mortality After the Introduction of Diphtheria-Tetanus-Pertussis Vaccine to Children Aged 6-35 Months in Guinea-Bissau: A Time for Reflection?
Front Public Health
A meta-analysis of three studies in Guinea-Bissau. Among those vaccinated with DTP, the mortality rate was twice as high comparing to those who were not vaccinated. The ratio was higher for girls. In addition, unvaccinated children were usually too sick or too weak to receive the vaccine, and their nutrition was poorer. They more often lived in rural areas where child mortality was generally higher. Therefore, the authors write, the negative effect of vaccination in these studies is underestimated.
There is no prospective study showing that DTP vaccination is associated with reduced mortality. Moreover, over the past 20 years, several studies have found that DTP is associated with higher mortality, especially among girls. However, three-dose coverage of this particular vaccine is used as a key indicator of the success of vaccination programs. Given that all studies, including the present one, suggest that DTP is associated with increased female mortality, this is really an illogical position. We need to use program performance indicators which are positively associated with better child survival.
WHO experts have argued that the negative effect of DTP is exaggerated, because studies have only been conducted in situations with herd immunity against pertussis and where the benefit of preventing pertussis would not be seen. However, pertussis was endemic in the 1980s before the roll out of the vaccination program in Guinea-Bissau, but all three studies of the introduction of DTP into urban and rural areas of Guinea-Bissau showed excess mortality associated with DTP vaccination.
Report of the Task Force on Pertussis and Pertussis Immunization-1988.
In Japan, there had been 37 compensation payments for vaccination-related deaths in 5 years beginning in 1970. That included 11 cases of SIDS. Then, due to the death of two infants within 24 hours of vaccination, the recommended vaccination age was raised from 3 to 24 months, and in the next 6.5 years there were only 3 compensations for vaccine-related deaths. The authors conclude that postponing vaccination until the age of 2 years reduces most of the severe adverse events associated with it.
Simultaneous sudden infant death syndrome.
J Forensic Leg Med
Twins (3.5 months age) received a second dose of DTP and OPV and the first dose of hepatitis B vaccine. They had fever and were given paracetamol. Two days later, both died in their sleep lying on their backs. It was determined that their death was not related to vaccinations, and that they died of an unknown reason.
Vaccination and cot deaths in perspective.
Arch Dis Child
Twins died simultaneously 3 hours after a DTP vaccination. The authors conclude that this happened after the vaccination by a coincidence, that according to their calculations 9 infants a year are expected to die accidentally within 24 hours after the vaccination in the UK, and that the risk of SIDS in twins is 3 times higher. They point out that the number of reported deaths has not reached the projected number.
In 20 years, only 6 deaths after DTP have been reported, but there have probably been other cases. In the 14 months following this high-profile case, 5 deaths were reported within 24 hours of vaccination.
Simultaneous sudden infant death syndrome: case report.
Hong Kong J Emerg Me
Two-month-old twins suddenly died 3 days after being vaccinated. It was determined that the deaths were unrelated to the vaccination and they died from SIDS.
The case of simultaneous sudden death of three-month-old twins 5 days after vaccination is described here. They received both 3-month and 1.5-month vaccinations. Cause of death is SIDS.
Here is a case description of simultaneous SIDS in 2.5-month-old twins two weeks after vaccination.
Here is a case of simultaneous SIDS in two-month-old twins, 18 days after the vaccination.
Here is a case of simultaneous death of ten-month-old twins the day after vaccination in 1945. The cause of death was determined to be anaphylactic shock, but nowadays their diagnosis would be considered SIDS. The authors cite several more cases of lethal anaphylactic shock which does not occurs instantly after the injection, but rather a few hours or a day after.
Sudden and unexpected deaths after the administration of hexavalent vaccines
Eur J Pediatr
The authors researched the mortality rate following administration of two hexavalent vaccines (Infanrix Hexa and Hexavac) in Germany. For children in the second year of life, the mortality rate within 24 hours of Hexavac was 31 times higher than expected.
The authors note that the number of cases of SIDS occurring a few days after vaccination is likely to be underestimated, as these cases are not reported to the Paul Erlich Institute (which documents cases of vaccination adverse events). For example, only one of the six SIDS cases that occurred within two weeks after hexavalent vaccination was reported. This case occurred within 24 hours after the vaccination.
Sudden unexpected deaths and vaccinations during the first two years of life in Italy: a case series study.
Unlike the previous study, a study of 3 million infants in Italy found no connection between hexavalent vaccine and SIDS in the second year of life. Instead it found that the risk of SIDS during the first week after Hexavac was 2.8 times higher, the risk of SIDS after the first dose of any hexavalent vaccine was 2.2 times higher, and the risk of SIDS during the week after the first dose of any vaccine was 1.5 times higher than in the control group.
The control group consisted of the same infants that were vaccinated, just before they were vaccinated and 14 days after. That is, if an infant died on the 15th day after the vaccination, his death would increase the likelihood that the vaccine was not related to SIDS, since that infant already would be a part of the control group.
A modified self-controlled case series method to examine association between multidose vaccinations and death.
The authors analyzed 300 death cases in Germany using a new statistical method and found that the fourth dose of the penta- or hexavalent vaccine was associated with a 16-fold increase in the risk of SIDS, and any dose of the vaccine was associated with a 2-fold increase in the risk.
Elevated serum concentrations of beta-tryptase, but not alpha-tryptase, in Sudden Infant Death Syndrome
Clin Exp Allergy
Beta-tryptase is an enzyme that is secreted from mast cells (a type of white blood cell). This enzyme is a marker of anaphylactic shock.
The authors analyzed the plasma of infants who died from SIDS and found that their beta-tryptase levels were significantly higher than those of infants who died with another diagnosis. They conclude that anaphylactic shock may be the cause of SIDS. More:  
Beta-tryptase and quantitative mast-cell increase in a sudden infant death following hexavalent immunization.
Forensic Sci Int
A healthy three-month-old infant refused to eat a few hours after the vaccination, then exhibited severe shortness of breath and was urgently taken to hospital, where he was diagnosed with shock and acute respiratory failure. Two hours after arriving at the hospital, despite resuscitation attempts, the child died.
He had high levels of beta-tryptase in his blood, from which the authors conclude that the cause of death was hexavalent vaccine (Infanrix Hexa).
Sudden infant death syndrome
A healthy three-month-old girl was vaccinated with hexavalent vaccine. An hour later she lost consciousness, another hour later an ambulance took her to a hospital, while attempting to resuscitate her. Two hours after arriving at the hospital, she was pronounced dead.
The authors point out that a full autopsy should be done at each case of SIDS, otherwise the connection between vaccination and death might not be established.
In 2003, the EMA (European analogue of the FDA) analyzed the deaths of 5 children who died within 24 hours after being vaccinated with hexavalent vaccine and concluded that vaccination is beneficial for every child in particular and for society as a whole, and the cause of death of these children remains unexplained and it is impossible to establish a causal relationship with the vaccination. EMA suggests that there is no plausible biological link between SIDS and the hexavalent vaccine.
Unexplained cases of sudden infant death shortly after hexavalent vaccination.
In six SIDS cases that occurred within 48 hours of being vaccinated with a hexavalent vaccine, autopsies were performed in Munich Institute. 5 of the infants were vaccinated with Hexavac and one with Infanrix Hexa. In addition to neuropathological and histological abnormalities, an unusual swelling of the brain was evident in all cases.
Brain weight gain due to edema or hyperemia (overflow of blood vessels) is mainly observed after DTP vaccination. Two of the three tested for tryptase showed very high levels.
The authors conclude that after the introduction of hexavalent vaccine, the number of SIDS deaths immediately after vaccination increased 13 times.
The previous article was strongly criticized. The critics pointed out that the authors are not experts on vaccination, that they refer to the article of a well-known opponent of vaccination, and the report contained grammatical errors. Other critics write that it is unclear which autopsy protocol was used, that the article was not systematically written, and that no vaccine is 100% effective or safe. Yet other suggest that comparison between present and historical data is problematic (it is interesting that the comparison between incidences of vaccine-preventable diseases before and after vaccination is not considered "problematic"), and that the authors should not dismay doctors and parents.
Hexavac was licensed in 2000 and recalled in 2005. But not because of the deaths incidence increase, of course, but because of "insufficient immunogenicity against hepatitis B". A scientist who worked at the Paul Erlich Institute, however, still thinks it was because of the mortality.
Sudden infant death following hexavalent vaccination: a neuropathologic study.
Curr Med Chem
11.8% of 110 sudden infant deaths occurred within a week after hexavalent vaccination (Infanrix Hexa and Hexavac). The authors suggest that some components of hexavalent vaccines can easily penetrate the hemato-encephalic barrier, which is still permeable in the first months of life, and they induce molecular changes in DNA, RNA and brain proteins that regulate vital functions. This is followed by lethal respiratory control disorder in predisposed infants. They note that the neurotoxicity of aluminum, including its ability to penetrate the hemato-encephalytic barrier and to induce inflammatory and neurodegenerative changes, has been demonstrated empirically.
Infanrix hexa and sudden death: a review of the periodic safety update reports submitted to the European Medicines Agency.
Indian J Med Ethics
The Infanrix Hexa manufacturer (GSK) submits to the EMA periodical confidential reports, which analyze the number of deaths immediately after vaccination and show that the number is lower than statistical expectations.
The authors analyzed three of these reports (15th, 16th and 19th), which were made publicly available by the Italian court, and found that the death cases that appeared in the 16th report were removed from the 19th. If we do take into account the cases from the 16th report, it turns out that the number of deaths within 4 days of vaccination among children over one year is much higher than could be expected.
The authors note that since SIDS statistics are collected by the manufacturer passively, its incidence is probably underestimated. On the other hand, the expected number of deaths is overestimated, since it is assumed that all the supplied vaccine doses have been used.
The authors do not understand why EMA accepted this report and call the manufacturer to explain why it removed these deaths from the report.
Mercury in vaccines from the Australian childhood immunization program schedule.
J Toxicol Environ Health A
The authors tested 8 different vaccines for mercury and found it in a concentration of 10 ppb in one of them only (Infanrix Hexa). Then they tested three other Infanrix Hexa vials and found mercury in a similar concentration again. The authors note that although this concentration is well below the established safety limit (2 μg/ml), the results of this study suggest inaccuracies in official documents and public communications claiming that the vaccine contains no mercury. They call for an urgent solution of this issue.
Infant mortality rates regressed against number of vaccine doses routinely given: Is there a biochemical or synergistic toxicity?
Hum Exp Toxicol
Before modern vaccination programs were introduced, "death in the cradle" was so rare that it was not included in infant mortality statistics. In the USA, national vaccination campaigns were launched in the 1960s. For the first time in history, most American children were required to receive several doses of vaccines, and soon after that, in 1969, a new medical term appeared – Sudden Infant Death Syndrome. By 1980, SIDS had become the main cause of postneonatal mortality.
In 1992, the American Academy of Pediatrics launched the "Back to Sleep" campaign, which encouraged parents to put their children to bed on their backs rather than on their stomachs.
Between 1992 and 2001, the incidence of SIDS decreased on average by 8.6% per year. However, the incidence of other causes of sudden unexpected infant death (SUID) has increased. For example, infant mortality from suffocation in bed has increased on average by 11.2% per year. Infant mortality from suffocation due to other causes as well as mortality in general has also increased. Similar observations were made in other studies as well.
Analysis of data from 1999 to 2001 shows that SIDS incidence continued to decline, but there was no significant change in overall postneonatal mortality. Although some studies have not found a correlation between SIDS and vaccines, there is evidence that some infants are more susceptible to SIDS after vaccination. For example, Torch found that two-thirds of the infants who died of SIDS were vaccinated with DTP. Of these, 6.5% died within 12 hours after vaccination; 13% within 24 hours; 26% within 3 days; and 37%, 61% and 70% within 1, 2 and 3 weeks respectively. Torch also found that non-vaccinated children died most often from SIDS in the fall or winter, while those vaccinated died most often at ages of 2 and 4 months – that is, when infants are first vaccinated with DTP. He concludes that the risks of vaccination may outweigh its potential benefits
Here is the CDC data. SIDS incidence in the US have declined significantly since 1992, but when considering all unexpected deaths altogether, their incidence decreased by 30% by the mid-1990s and has remained virtually unchanged since then.
Native and African Americans die from sudden causes twice as often as whites and 5 times as often as Asians.
The mortality rate of infants from suffocation in bed has increased more than tenfold since the 1990s, although the recommendation to place children on their backs should have reduce the incidence of suffocation. The CDC, for some reason, has nothing to say about this fact.
The same happens in Australia – although the SIDS incidence is decreasing, the number of deaths from suffocation is increasing. More: 
Defining the sudden infant death syndrome
In 1991, the definition of SIDS was changed. For example, autopsy and investigation of the stage of death were not previously required, but have now become mandatory. It also became necessary to investigate personal and family medical history. However, the new definition is by far applied to 35% of cases only. In 7% of cases the definition from 1969 is used, and which definition is used in the remaining cases is unclear.
Mississippi has a 12 times higher SIDS incidence than New York. In some states, investigators do not use SIDS as a cause of death if any other cause is suspected. SIDS incidence may vary within 300-400% from district to district in the same state. More: 
Supine and prone infant positioning: a winning combination.
J Perinat Educ
Prior to the 1990s, nearly all infants in the United States were placed for sleep in the prone or “tummy” position. In 1992, the American Academy of Pediatrics (AAP) published a position statement recommending that all infants be placed in nonprone positioning for sleep with the intended purpose of decreasing the incidence of SIDS. In 1996, the AAP position was amended to promote supine sleep as the preferred position. Sometimes, however, when medical practice changes, unforeseen consequences arise in other areas.
Prior to the Back to Sleep campaign, infants who slept in the prone position also tended to spend awake time in the prone position. When an infant awakes in prone and becomes fussy or bored, it naturally learns to push up on its forearms and lift its head to explore the environment. Pushing up against gravity also has the added benefit of strengthening the muscles used in other prone skills. Infants who sleep in a supine position are not in the appropriate position upon awakening to achieve these skills spontaneously. Without adequate prone time, the antigravity motor patterns may be underdeveloped.
Motor skills: The first trend noted following the change to supine sleep positioning involves delays in acquisition of early gross motor milestones. Those sleeping on their backs begin to turn over, sit, crawl and get up with a delay, compared to those sleeping on their stomachs.
Shoulder retraction: Shoulder external rotation and retraction with scapular adduction has been seen more frequently since the change in sleep position. Some infants get "stuck" in this position, which can affect fine motor skills and other skills.
Positional Torticollis: More often observed in infants sleeping on their backs. With torticollis, the infant is unable to turn his head away from the affected area, which over time may cause mild facial asymmetry, range restriction of the neck, delayed development of postural control, and alteration in visual gaze to one side.
Positional Plagiocephaly ("flat head syndrome"): Infants sleeping on their backs have a higher risk of flattening of the skull. Between 1992 and 1994, 6 times more cases of plagiocephaly were reported than in the previous 13 years. Babies with plagiocephaly are more likely to lag behind in cognitive and psychomotor development. 40% of them need special education, compared to 8% of infants without plagiocephaly. Untreated plagiocephaly can also cause abnormal occlusion, temporomandibular joint difficulties, and strabismus.
A case is described of a girl who's slept on the same side since birth. The parents didn't put it on her stomach during the day because she didn't like it. She developed torticollis, plagiocephaly, asymmetrical forehead and skull, and delayed motor skills.
The author concludes that infants should still sleep on your back, but they should be put on the stomach during playtime for at least for 15 minutes a day. More: 
Apart from the above effects, sleep on the back and lack of time on the stomach also lead to brachycephaly (short head).
Special clinics for plagiocephaly treatment have appeared in Canada. By 2013 plagiocephaly was already observed in 46% of three-month infants.
Prone or Supine?
The fact that motor skills development is delayed in infants who sleep on their backs was known since the early 1960s. It was also known that the prone position helps with evening cramps. 
The hypothesis described here suggests that sleeping on the back increases the risk of autism, as in five countries (Denmark, the United Kingdom, Australia, Israel and the United States) a sharp increase in autism started immediately after campaigns recommending that infants be placed on their backs. The author writes that the data quality in support of this hypothesis is quite low, but the correlation between sleep in the prone position and SIDS was based on data of similar quality. The author also notes that biologically speaking, sleep in the prone position is more natural and healthy, as almost all mammals (except bats and sloths) sleep that way.
Sudden infant death syndrome: a possible primary cause.
J Forensic Sci Soc
The authors analyzed more than 100 mattresses on which infants who died of SIDS were sleeping. In all of them, the fungus Scopulariopsis brevicaulis was found in the area that was heated by baby's breath. Also such extremely toxic gases as phosphine, arsine and stibine were detected as well. These gases are released by the fungus while it processes phosphorus, arsenic and antimony respectively. The manufacturers add these ingredients to PVC mattresses as fire-retardant materials.
There have always been unanticipated and unexplained deaths, but their incidence increased dramatically 40 years ago. In England, it peaked in 1986-88, and it was then that the most fireproof materials based on phosphorus and antimony were introduced to mattresses production. In Japan, for example, where boron is used as a fire-retardant material, SIDS is not common.
An infant who sleeps on the stomach is exposed to these gases more. Excessive wrapping also increases the risk, as it leads to hyperthermia and increased production of toxic gases. It also explains why sleeping the back reduces the risk of SIDS. It is reported that 100,000 mattresses were wrapped with polyethylene in New Zealand, and there have been no recorded cases of SIDS when those mattresses were used. In Russia, mattresses are usually covered with rubber, and SIDS is practically nonexistent there. More: , 
In response to this hypothesis, an expert committee was set up in the UK. It issued a report that concluded in its report that the hypothesis is incorrect and that the fire resistant materials are safe.
- The committee found a bacterium instead of a fungus, trimethylarsin instead of arsine, and trimethylsurma instead of stibine. These materials are less toxic and probably are not produced at normal temperatures.
Cook's report (from another committee) found that the concentration of antimony in the liver and blood of those who died of SIDS was higher than normal, and correlated with the antimony content in the mattresses. Infants were also found to have higher levels of antimony than their mothers. But the expert committee concluded that those measurements were unreliable. The levels of antimony in the lungs and blood of infants who died in womb were similar to those in adults, which means that the mattresses had nothing to do with it.
- One study found elevated levels of antimony in the liver in 52% of those who died from SIDS, but only 6% of the control group. Subsequent studies, however, did not find a significant difference between those who died from SIDS and those who died from other causes.
- The committee confirmed that the antimony content of the infants' hair was indeed higher than that of their mothers', but found no correlation with the level of antimony in the mattresses. It concluded that antimony is found in healthy infants as well, which suggests that it is safe in these concentrations. In addition, antimony is found in many products, such as polyester fabrics, which means it is in the dust that we breathe and swallow. If you rub polyester fabric against your hair, antimony remains on it, which also means that the mattresses have nothing to do with SIDS.
Re-use of a mattress is associated with a three-fold risk of SIDS. The risk was higher if the mattress was borrowed from another family. More:
In Sweden, there was a correlation between the incidence of SIDS and the nitrates level in water.
In utero and childhood polybrominated diphenyl ether
Environ Health Perspect
Fire protective materials (flame retardants) are found in furniture, mattresses, pillows, electronic equipment, baby products, textiles, cars, carpets, and household plastic products, from where they are distributed to the environment, starting from eagles and including whales and dolphins.
Prenatal and childhood levels of brominated flame retardants are associated with poorer attention, fine motor coordination, and cognition. They penetrate the placenta and are secreted in breast milk, and are neurotoxic.
Flame retardants are associated with decreased fertility in women, hormonal disorders and decreased sperm quality in men, low weight and reduced head circumference in infants, low IQ in children and thyroid cancer.
Flame retardants are also found in household and car dust. 55 of the 62 flame retardant materials were found in house dust. Flame retardant concentrations found in children's blood are three times higher than those in their mothers'.
Sudden unexplained death in childhood is no longer defined as SIDS but as SUDC (Sudden unexplained death in childhood). SUDC is considered a very rare cause of death. In the United States there are around 400 SUDC cases a year, and there are almost no scientific articles on this phenomenon. In comparison, invasive meningococcal infection death cases number is an order of magnitude less.
An 18-month-old child was vaccinated with MMR, even though he was sick. He died ten days later. The pathologist found that the child's death was not related to the vaccination, as his symptoms appeared too quickly after the vaccination to be related to it, and the child died of SIDS.
In 2011, a healthy four-month-old infant in the United States received 7 vaccines and died the next day with a diagnosis of SIDS. In July 2017, the Special Masters court decided that the vaccines played a significant role in the boy's death, and without their influence he would not have died.
SIDS and Vaccination
Infanrix Hexa and other hexavalent vaccines
The aftermath of the "Back to Sleep" campaign
Full-text of papers mentioned above on Google.Drive