The prevalence, trends and heterogeneity in maternal smoking around birth between the 1930s and 1970s

This paper shows the prevalence, trends and heterogeneity in maternal smoking around birth in the United Kingdom, focusing on the war and post-war reconstruction period in which there exists surprisingly little systematic data on (maternal) smoking behaviours. Within this context, we highlight relevant events, the release of new information about the harms of smoking, and changes in (government) policy aimed at reducing smoking prevalence. We show stark changes in smoking prevalence over a 30-year period, highlight the onset of the social gradient in smoking, as well as genetic heterogeneities in smoking trends. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement We gratefully acknowledge financial support from NORFACE DIAL (462-16-100) and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 851725). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: UK Biobank has received ethical approval from the National Health Service Northwest Centre for Research Ethics Committee (11/NW/0382) and has obtained informed consent from its participants. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes This work is based on data from the UK Biobank which are accessible to researchers online by application and payment of a fee. This work is also based on data provided through [www.VisionofBritain.org.uk][1] and uses historical material which is copyright of the Great Britain Historical GIS Project and the University of Portsmouth. [1]: https://www.VisionofBritain.org.uk