Current suggestions

The following suggestions for the bedding of infants who may be genetically predisposed to atopy or asthma are based on the evidence discussed in
this paper, and current recommendations on SIDS.

1 Impermeable encasings (available from Manchester shops and some department stores) should be used for bedding items (mattresses, quilts, pillows) for infants and children at risk of atopy to reduce exposure to house dust mites and their allergens.^{<Level of evidence II>}

Some health funds may provide a rebate for purchase of these items. If covers are not available, blankets and non-encased washable doonas should be washed at least every two months (see below).

2 Due to the likely increase in the risk of SIDS, soft bedding (pillows, quilts) should not be used for infants under 12 months of age.

3 Washable bedding items used for infants and children, including cotton blankets and soft toys, should be washed weekly at >55°C.^{<Level
of evidence II>} It is not necessary to use an acaricidal laundry product.

4 The use of sheepskins as under bedding is linked to high dust mite sensitisation and increased risk of SIDS in infants under 12 months. It should therefore be avoided.^{<Level of evidence II>}

5 Low allergen bedding should be used for infants and children. Feather bedding has substantially lower house dust mite allergen levels than synthetic bedding.^{<Level of evidence III-2>}

Where impermeable casings are used, tightly woven fabric encasings are preferable to plastic covers.

It is important to note that even if these suggestions are carried out, there is still a significant chance that high-risk infants will develop asthma.

Bedding and primary prevention of asthma

The increase in the prevalence of allergy-related asthma over the last two decades, and recognition that the increase may have resulted from environmental changes,^1-3 have highlighted the need for further investigation of primary preventive strategies in high-risk infants.³ Infant bedding is one area that has come under close scrutiny, largely because infants spend prolonged periods in close proximity to bedding items.^4-6

The main reason that interventions have targeted bedding is that mattresses and other bedding items are significant reservoirs of house dust mite (HDM) allergens,^7-10 and the bedding environment may therefore play a role in increasing an infant’s likelihood of HDM sensitisation.^{5,
11} However, while some studies have shown an association between sensitisation and childhood asthma,^{12,
13}the relationship between allergen exposure and development of asthma is as yet unproven.¹⁴ A growing body of research indicates that the prevalence of asthma may be independent of allergen exposure in early life,^{15,
16} with this being substantiated by the number of young children in whom asthma occurs in the absence of allergen sensitisation.^{15,
17}

As well as investigating measures to reduce exposure to HDM allergens, recent studies have examined the effects of different types of bedding. Feather bedding had long been considered
a potential source of allergen exposure and thus a potential risk factor for asthma.¹⁸ However, several studies have found an association between synthetic bedding and increased childhood wheeze.^{6,
19-21} The mechanisms for this effect remain unclear but volatile organic compounds in synthetic bedding items, including HDM-impermeable mattress covers,
may play a role.²²

Primary preventive measures target a population that is still healthy but at risk of a disease, mostly using a range of interventions. However, it remains uncertain whether manipulation of factors associated with the development of asthma can reduce prevalence or delay onset.

Quality of the evidence

This paper is based on review of the recent literature as outlined below.

Sources of evidence

Systematic reviews, including Cochrane reviews on feather versus non-feather bedding and HDM control in asthma management
Randomised controlled trials into factors contributing to the development of atopic diseases, in particular asthma.
Other studies exploring the aetiology and prevention of atopic diseases, in particular asthma.

While there is increasing interest in the prevention of asthma in those genetically at risk,² there remain a number of limitations to the available evidence.

Limitations of existing evidence

There are difficulties in defining asthma in children under
five years.
Studies have tended to measure outcomes other than asthma (eg wheeze or atopic disease).
The fact that many of the studies are so recent means that there has been limited time for follow-up.
Many trials use a combination of interventions and outcomes are not always separable.

It should also be noted that the studies tend to focus on infants at high risk of atopy or asthma (usually on the basis of family history) so findings may not be applicable to the general population.