What is cot death (SIDS)? Cot death (SIDS) is the most common cause of infant death in many western countries. In most cases the baby has been put down to sleep in his or her cot (crib) and later found lifeless, with no sign of illness or physical struggle. Cot death can also occur in other situations which parallel "cot situations" or which are sleeping environments, for example: prams, carseats, playmats, sofas, and adults' and children's beds.   What is the cot death risk age? If a baby was born at full term, with a normal birth weight, and does not experience any significant health problems, the risk age can be regarded as over at one year. If any of those situations does not apply (for example, if the baby was premature), the risk age can extend out to fifteen months.   What is the cause of cot death? Cot death is caused by highly toxic nerve gases which can be generated from mattresses and other bedding used in babies' cots. The gases are generated by action of common household fungi on compounds of phosphorus, arsenic and antimony present in the mattress or bedding.   How can cot death be prevented? By preventing exposure of the baby to the toxic gases which cause cot death. This is done by wrapping the baby's mattress in accordance with a specified protocol (to separate the baby from gas generation in the mattress) and using specified bedding (so that the gases cannot be generated on top of the wrapped mattress). For information on how to wrap a baby's mattress for cot death prevention click on How to prevent SIDS.   Why do cot death babies show no symptoms? The toxic gases which cause cot death are anticholinesterase agents. They depress the baby's central nervous system, resulting in cessation of the heart and lung functions. Babies who die of cot death are not "ill" in the medical sense; they are poisoned by environmental gaseous poisoning.     What is a "near miss"? A "near miss" occurs where a baby has been seriously affected by the toxic gas/es which cause cot death but is still alive. The baby's heart and lung functions may have stopped.  "Near miss" babies often have blue lips (indicating shortage of air). If at this stage the baby is picked up and air is blown onto his or her face, the baby may start breathing again. If a partly poisoned baby is moved into fresh air and can be made to breathe, the baby usually survives.   What research has been done into the toxic gas theory for cot death? A large amount of research relating to the toxic gas theory has been published in peer-reviewed scientific journals.  Every step in the fungal generation of toxic gases from infant bedding has been proved. Mattress-wrapping for cot death prevention is supported by wider research than supported the introduction of various items of orthodox advice (including face-up sleeping). For more information about research, click on Research and Statistics.     Didn't the 1998 UK Limerick Report disprove the toxic gas theory for cot death? No. For more information about the Limerick Report click on the sidebar heading Limerick Report.     Didn't the UK CESDI Study find that three babies in Britain died on polythene-wrapped mattresses? No.  There is no evidence that these mattresses were wrapped in polythene. For such a claim to be valid, chemical analysis of the plastic was required; however no such analyses were carried out. In February 2000 Professor Peter Fleming (an author of the CESDI Study) conceded that the CESDI study had not demonstrated that the mattresses on which the babies died were wrapped in polythene.   Why are recently vaccinated babies and babies with infections at higher risk of cot death? The fever which results from infection and which can also follow vaccination results in increased temperature in the baby's cot. If bedding in the cot is capable of toxic gas generation, a rise in temperature of (say) three degrees Celsius in the cot can result in a tenfold increase in the rate of gas generation.     Why does the risk of cot death rise from one baby in a family to the next? Many parents re-use cot mattresses from one baby to the next. If a mattress contains phosphorus, arsenic or antimony and certain household fungi have become established in the mattress during previous use by another baby, generation of toxic gas commences sooner and in greater volume when the mattress is re-used for the next baby.   Why do babies of solo parents have a very high cot death rate? For economic reasons, solo parents are more likely to sleep their babies on previously used mattresses which they have acquired secondhand. The risk of cot death increases as a mattress is re-used from one baby to the next.     Why does overheating increase cot death risk? The extra warmth in the baby's cot causes the fungus to increase gas generation. A rise in temperature of three degrees Celsius in a baby's cot can cause gas generation to increase tenfold or more.   Why do more cot deaths occur in winter than in summer? During winter babies frequently use more bedding, resulting in greater risk of overheating in the cot and thus greater risk of gas generation. Also, windows and doors are more likely to be closed during winter, decreasing ventilation around the baby's cot. As a result, draughts which could cause gases to disperse are reduced or eliminated.   Why does face-up sleeping reduce the risk of cot death? The gases which cause cot death (phosphines, arsines and stibines) are all more dense than air. They diffuse away from a baby's mattress towards the floor, so a baby sleeping face-up is less likely to ingest them.   Why does bedsharing between adults and babies pose cot death risk? Adults' mattresses frequently contain the same chemicals and fungi as babies mattresses, and therefore can generate the same toxic gases. For physiological reasons adults are not put at risk by this gas generation in beds, but a bedsharing baby can die within a short period of time.   Why do dummies (pacifiers, soothers) appear to reduce cot death risk? Mothers who wish to use a dummy will very often sleep the baby face-up so that the dummy stays in place. And face-up sleeping reduces the risk of cot death, because the gases which cause cot death are more dense than air and a baby sleeping face-up is less likely to ingest them. So it is not the dummy which reduces cot death risk, but rather the statistical likelihood that the baby using the dummy will be sleeping face-up.   Cot death rates in various countries fell during the 1990s but have now levelled out and are no longer falling. Why is this? In most countries these reductions in cot death rates were the result of face-up sleeping campaigns. However, for reasons relating to the chemistry of the gases which cause cot death, face-up sleeping is only a partial preventive. In particular, it is not very effective against the danger posed by phosphine. As a result, all face-up sleeping campaigns (wherever they occur) achieve a reduction of around 40~45% in the cot death rate, at which point the rate hits a plateau and does not fall further. This plateau has now been reached in the USA and Canada.   In many countries where there is an indigenous or coloured minority population, that group has a much higher cot death rate than the local European population. Why is this? Cot death has a strong socio-economic bias, because less well-off parents are much more likely to use secondhand or previously used mattresses for their babies. Since, therefore, indigenous and coloured populations are frequently in low income groups (e.g. African Americans, Canadian Indians, Australian Aborigines and Maori New Zealanders), these groups also have very high cot death rates. In addition, some minority ethnic groups (e.g. Maori New Zealanders) traditionally bedshare with their babies, and adults' mattresses are by definition re-used mattresses.   How does the toxic gas theory explain cot deaths which occur in adults' arms? If a baby has been lying in a cot or on some surface where he or she has been exposed to a lethal dose of toxic gas, and as a result the mechanism of death is already occurring when the baby is picked up, the baby can die while being held in the adult's arms. Also, cot death can occur in an adult's arms if a baby is picked up and held in an item of  bedding which is generating toxic gas.   Is cot death cause by babies re-breathing their exhaled carbon dioxide? No. All babies exhale a similar amount of carbon dioxide, regardless of whether they are first, second, third or later babies in a family. Therefore, the statistical finding that the cot death rate rises from one sibling in a family to the next disproves the carbon dioxide theory.     Does cot death have any medical or physiological cause? No. For more information on this topic click on the sidebar heading Cot death: no medical cause.     Autopsies have shown that cot death babies frequently have bacterial and fungal infections in their throats and lungs. Why is this? The conditions in the baby's bedding which favoured the growth of fungi generating toxic gases would also have favoured the growth of other micro-organisms, which the baby has then breathed in. Many of these other micro-organisms would be harmless, but they would still be noticeable at autopsy.   Why aren't there many cot deaths among babies less than one month old? A significant number of babies sleep on new mattresses, and it takes around one month for fungi capable of gas generation to become established in a mattress. However, a baby less than one month old can die of cot death if he or she is placed on a mattress which has recently been used by another baby and is already capable of generating toxic gas.   Why do relatively few cot deaths occur among babies over six months old? An older baby is more able to respond physically to the initial distress which is caused the exposure to the toxic gases. An older baby experiencing this distress (e.g. the initial headache which occurs) can take action by flailing around in the cot, throwing off bedding, or sitting or standing up in the cot. This attracts the attention of adults. It also disperses gases from around the baby; or physically removes the baby from the gases (if the baby sits or stands up in the cot), since these gases are more dense than air.   Why is the cot death rate higher for twins than for singleton babies? First, if the twins are not the mother's first pregnancy, often the mother already has a cot mattress. Secondly, many twins sleep in the same cot when they are very young babies, but at some point while still within the cot death risk age are separated so that they are sleeping in separate cots. Both of these situations require a second mattress to be obtained. As a consequence, it often occurs that one twin in a family sleeps on a previously used mattress, while the other twin sleeps on a new mattress. This has the result that the cot death rate among twins is significantly higher than among singleton babies; also it is statistically much more likely that one twin will die of cot death than the other. The twin sleeping on the re-used mattress is at around double the cot death risk of the twin sleeping on the new mattress.   Given that millions of unwrapped mattresses contain phosphorus, arsenic or antimony, why aren't there more cot deaths? In order for cot death to occur, the following circumstances must co-exist in the baby's cot: 1.  The mattress (or other bedding) beneath the baby must contain phosphorus, arsenic or antimony. 2.  The condition of the mattress or bedding must support fungal growth (for example, be damp with sweat or milk, or contaminated with urine). 3.  Fungi capable of generating gases from phosphorus, arsenic and antimony must be growing in the mattress or bedding. 4.  The fungi must be sufficiently active to produce a lethal dose of the gases. 5.  The baby must ingest a lethal dose (for example, because the baby is sleeping face down, or because there is insufficient ventilation around the baby to disperse the gases).   It is uncommon for all these circumstances to co-exist in a baby's cot. Many babies are exposed to sub-lethal doses of toxic gas/es in their cots, and no immediate harm results.  Occasionally, however, all the above circumstances do co-exist and a cot death ensues.