Their participation in the MAS study over 3 decades has served the scientific community well, leading to many learned lessons. Read more here.
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Frequencies of Allergic Diseases
Of the 3 most common allergic diseases, atopic dermatitis (atopic dermatitis or atopic eczema) usually begins in infancy, while asthma and allergic rhinitis (all year round or seasonal as hayfever) may occur early, but increasingly in their incidence become relevant in school and adolescence. Since the frequencies of allergic diseases u.a. depending on whether or not the parents are allergic or not, we will distinguish these two groups below.
Over 40% of all MAS participants with one or two allergic parents had at least one of the 3 most common allergic diseases at the age of 20: a total of 26% "only" one (14% allergic rhinitis, 7% eczema, 5% Asthma), but about 17% two or all three disorders at the same time (see Gough, H. et al., 2015).
In the case of MAS participants without allergic parents, at the age of 20 only about 25% had at least one of the 3 most frequent allergies: a total of 18% "only" one (8% atopic dermatitis, 7% allergic rhinitis, 3% asthma), and about 7% two or all three of these diseases at the same time (see Gough, H. et al., 2015).
While significantly more boys than girls developed asthma or allergic rhinitis in early and late school age, an equal number of girls and boys were affected by atopic dermatitis at this age.
For asthma, the sex ratio was balanced at age 20, while allergic rhinitis was still more common in male than female persons. Atopic dermatitis at the age of 20 affected twice as many women as men (see Gough, H. et al., 2015).
Lifestyle and Environmental Factors
Having a mother who smoked during pregnancy or later in her child's life increased its risk of developing asthma in the first 20 years (Grabenhenrich, L.B. et al., 2014).
Breastfeeding was not an allergy-protective factor in the MAS study. Nevertheless, breastfeeding for nutritional reasons is recommended for at least 4-6 months.
Owning fur or feathered pets during the first 3 years of life did not increase the risk of developing asthma later in school age. For dogs, a slight protective effect was found. However, if allergic reactions to pets are known, pets should of course be avoided (Lodrup Carlsen, K.C. et al., 2012).
Many studies have shown that children who were in kindergarten or preschool rarely developed allergies. New findings from MAS suggest that the age at which a child first enters a kindergarten or preschool may also have an impact. We found that children who started between 18 and 36 months of age were better protected from allergies than those who started prior to 18 months or later than 36 months of their age respectively (Grabenhenrich, L.B. et al., 2014).