INTRODUCTION: In this review a selection of studies published during the period 2002-2010, based on data from the Danish National Birth Cohort linked with other health registers, is described. Illustrative examples of studies addressing perinatal health outcomes (pregnancy complications and fetal and infant health) of a variety of exposures during pregnancy, as well as examples showing different methodological approaches in design and analyses of the studies, are presented. RESEARCH TOPICS: The exposures of interest include alcohol drinking, coffee intake, smoking, use of nicotine substitutes, physical exercise, working conditions, medication and infections during pregnancy, and environmental possible toxins. The study designs cover straightforward cohort analyses, case-control studies and sub-cohort analyses with enriched data collection. CONCLUSION: So far, the Danish National Birth Cohort has provided important knowledge for evidence-based antenatal care by giving more accurate risk estimates for adverse pregnancy outcomes associated with the exposures of interest. Some new potential hazardous exposures during pregnancy have been identified and others have been put to rest. We believe that this investment in epidemiologic infrastructure was well spent. The existence of the Danish National Birth Cohort together with other cohorts and national registers has given Denmark a leading position in reproductive epidemiology.