Den yngste del af Det Danske Tvillingregister: Etablering og analyse af zygotispecifikke tvillingfødselsrater

In order to be able to study the aetiology and pathogenesis of diseases with manifestation in childhood and youth a Danish register of young twins has been established. The compilation of the register is based on the Danish Civil Registration System, with the Danish Vital Statistics as source of validation. All twins were sent a one side questionnaire asking about diabetes, willingness to participate in other projects and pairwise similarity in the twins. Comprising 20,888 twin pairs the register covers 74.4953-67 (incl.) and 97.4968-82 (incl.). The response rate of the questionnaire study was 92.39 180 twin pairs. Ninety-six percent of the respondent twins declared their willingness to participate in additional studies. An analysis of trends in the twinning rates for the years 1968-82 showed that the rate in monozygotic twinning is increasing and the twinning rate of opposite-sexed twin pairs is decreasing, thus confirming earlier estimated trends in twinning rates. This register provides a valuable resource for future twin studies.