The prevalence of smoking has declined in Norway since the end of the 1990es in the whole population of women as well as among pregnant women. However, both the data quality as well as trends in pregnancy smoking had differed between counties in the last decade. The aims of the study were twofold; to describe and evaluate the data quality of smoking habits over time and to describe national and regional trends in smoking prevalence in all pregnant women as well as in social and demographic subgroups in Norway since 1999. The Medical Birth Registry of Norway (MBRN) has national coverage of all births of 16 or more gestational weeks. Since 1999, women have been asked about tobacco smoking at the beginning and at the end of pregnancy. We will include records from all women giving birth in the years from 1999 and up to the last available year of data from MBRN. The MBRN data will be linked to the education register in Statistics Norway.
Some parts of this study are a follow up on previous analyses from the Medical Birth Registry of Norway.
