The ups and downs of birth rate in Switzerland 2020 to 2023 in a historical context

We follow population trends in the birth rate in Switzerland almost up to the present day and place the latest developments during the Covid-19 pandemic in a historical context. The birth rate in 2022 was the lowest it has been since the 1870s, and it seems the trend is continuing in 2023. The latest decline had already begun 1-2 years before Covid-19. Previous pandemics (1890, 1918, 1920, 1957) had each led to a temporary decline in the birth rate around 9 months after the peak of these outbreaks. With Covid-19, this appears more complex. The immediate shock of the global outbreak has not left a nega-tive mark on births in Switzerland. However, during and shortly after the first two pandemic waves and partial shutdowns in 2020, there were more conceptions and thus significantly more births in 2021, in all available subgroups except Italian-speaking Switzerland, and somewhat more pronounced among >30-year-old mothers and second parities. The subsequent decline in births from January 2022 was stronger than the increase in births in 2021. The first part of the 2022 decline falls on conception months in the first half of 2021, when the vaccination campaign started in Switzerland. However, given that the proportion of young people vaccinated by summer was still small, vaccination cannot by itself explain the decline in birth rate. The second part of the 2022 decline is associated with conceptions during the large Omicron wave in winter 2021/2022. The decline appears to continue in 2023, albeit not substantially. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the Swiss National Science Foundation under Grant 197305. ### 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: According to the Human Research Act HRA, no ethical approval is required when working with fully anonymized government data. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the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 The data used in this study are publicly available from the Swiss Federal Statistical Office or can be ordered from them in a fully anonymised form.