Recent reports linking cot deaths, or sudden infant death syndrome (SIDS) with a face-down sleeping position in the baby are supported by WA scientists J.A. Corbyn and P. Matthews. In their paper, the scientists argue that the major contributory causes of SIDS are environmental.
"The investigations show that if babies are left alone in the absence of minor draughts then excess carbon dioxide, ammonia or other pollutants can accumulate at the face of the baby", wrote Corbyn.
According to the paper, cot death appears to be more common during winter and among poorer sections of the population, although it is known to occur in all social groups. The incidence of cot death varies from 0.3 per thousand in Hong Kong, 0.6 per thousand in Sweden to 4 or more per thousand in parts of Britain, Germany, New Zealand and Tasmania. It can occur any time during the first year, although there appears to be an increased likelihood at about six months of age.
The authors argue that a significant number of cot deaths can be explained in terms of exceptional levels of ammonia, carbon dioxide and/or other pollutants in the air being breathed by the baby. Ammonia could affect the nervous system, triggering a reflex associated with cot death. This reflex could be associated with pollutants or with the baby lying face down.
"The circumstances favourable to such dangers are thus those that result in the accumulation of dangerous gases/gaseous combinations at the face of the baby", the authors write. In practical terms, it was important to always ensure that air currents existed at the face of the baby, and to avoid soft, air-trapping bedding.
The ammonia and carbon dioxide levels in the baby's environment were primarily due to urine and respiration respectively. The use of commercial nappy treatment and baby care products, and the use of artificial feeding formulas could lead to increased ammonia gases in the baby's environment.
"Reduction in the production of ammonia in a nappy depends on ensuring the chemical environment is slightly acidic rather than alkaline as acid conditions are unfavourable to the action of the enzyme urease which converts urea to ammonia.
"The chlorine-based disinfectants commonly used for nappies do not inhibit the action of urease and provide an alkaline environment. Skin creams and lotions are also generally alkaline, as this promotes a smooth skin."
Excess ammonia-producing urea in the nappy "can be derived from unsuitable types and amounts of protein if the baby is artificially fed or has supplements."
The authors recommend that babies not sleep in a face-down position, or be encouraged to sleep through the night. Both of these could lead to the formation of polluting gases at the baby's face.