[Both risky and "healthy" factors in the allergy prevention counseling]

Most recommendations in order to prevent childhood allergy are based on data gained in retrospective studies. In future it is important that such recommendations are based on intervention studies. Results from prospective birth cohort studies may also be used, since ethical issues must be taken into consideration when interfering on matters like parental smoking, breast-feeding, the keeping of furred pets and the unsuitability of living in damp houses.