For investigation of the effect of being vaccinated with DTaP-IPV-Hib compared with being non-vaccinated a Cox proportional hazards regression with age as the underlying time will be used to estimate the adjusted HR of developing atopic dermatitis among children vaccinated with DTaP-IPV-Hib compared with unvaccinated children. Vaccination status will be assessed from time of scheduled vaccination (3 months of age) and set as a time dependent variable with the categories unvaccinated and vaccinated.