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:
-
maternal dietary antigen avoidance in pregnancy and
lactation9
-
the optimal duration of breastfeeding35
-
the use of hydrolysed protein in allergy prevention10
-
cow’s milk protein avoidance and childhood wheeze.19
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 of age.
-
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 are
not applicable to the general population.
Summary of current evidence
Pregnancy
|
|
| Antigen avoidance during pregnancy is unlikely to
reduce the risk of giving birth to an atopic child and may have an
adverse effect on maternal and/or foetal nutritional status.9
Note that the studies included in this review related to atopic
disease in general and not to asthma specifically. |
Level I |
| Lactobacillus supplementation in pregnancy may play
a role in preventing or delaying atopic disease in children at high
risk.27,
32 The primary outcome examined in this study was atopic
eczema. |
Level II |
Breastfeeding
|
|
| There are numerous health benefits for infants who
are exclusively breastfed for 6 months. No growth deficits have been
demonstrated among such infants.35
|
Level I |
| Exclusive breast-feeding for 4 months or more after
birth is associated with lower prevalence of childhood asthma.14,
17 |
Level I |
| A maternal antigen avoidance diet during lactation
may reduce the infant’s risk of developing atopic eczema.9
Other atopic diseases, including asthma, have not been studied. |
Level I |
| Lactobacillus supplementation during lactation may
increase the immunoprotective potential of breastmilk.33
The primary outcome examined in this study was atopic eczema. |
Level II |
| Supplementing infant dietary omega-3 fatty acids
may reduce the likelihood of wheeze during the first 3 years of
life.20,
34 |
Level II |
If breastfeeding is not possible
|
|
| The use of hydrolysed formula for 4 months or more,
in addition to dietary restrictions and house dust mite reduction,
is associated with a lower risk of wheeze in the first year of life
compared to standard cow’s milk based formula.10,
19
|
Level I |
| There is insufficient evidence to suggest that
soya-based milk formula instead of standard cow’s milk based formula
modifies the risk of developing asthma or wheeze.10 |
Level I |
| Infant supplementation with Lactobacillus for the
first 6 months combined with prenatal maternal supplementation may
play a role in the prevention of atopic disease in children at high
risk.27,
32 The primary outcome examined in this study was atopic
eczema. |
Level II |
| Supplementing infant dietary omega-3 fatty acids
may reduce the likelihood of wheeze during the first 3 years of
life.20,
34 |
Level II |
