A prospective birth cohort study of different risk factors for development of allergic diseases in offspring of non-atopic parents.

BACKGROUND

Allergic diseases are thought to be inherited. Prevalence of allergic diseases has, however, increased dramatically in last decades, suggesting environmental causes for the development of allergic diseases.

OBJECTIVE

We studied risk factors associated with the development of atopic dermatitis (AD), allergic rhinitis (AR) and asthma (AS) in children of non-atopic parents in a subtropical country.

METHODS

In a birth cohort of 1,497 newborns, parents were prenatally enrolled and validated for allergic diseases by questionnaire, physician-verified and total or specific Immunoglobulin E (IgE) levels; 1,236 and 756 children, respectively, completed their 3-year and 6-year follow-up. Clinical examination, questionnaire, and blood samples for total and specific IgE of the children were collected at each follow-up visit.

RESULTS

Prevalence of AD, AR and AS was, respectively, 8.2%, 30.8% and 12.4% in children of non-atopic parents. Prevalence of AR (p<.001) and AS (p=.018) was significantly higher in children of parents who were both atopic. A combination of Cesarean section (C/S) and breastfeeding for more than 1 month showed the highest risk for AD (OR=3.111, p=.006). Infants living in homes with curtains and no air filters had the highest risk for AR (OR=2.647, p<.001), and male infants of non-atopic parents living in homes without air filters had the highest risk for AS (OR=1.930, p=.039).

CONCLUSIONS

Breastfeeding and C/S affect development of AD. Gender, use of curtains and/or air filters affect AR and AS, suggesting that control of the perinatal environment is necessary for the prevention of atopic diseases in children of non-atopic parents.