Abstract
Background
Speculative claims about COVID-19 vaccines affecting fertility and childbirth have circulated widely. We aimed to examine whether COVID-19 vaccination is causally associated with childbirth in Swedish women.
Methods
We conducted a cohort study using a representative population of 369,000 to emulate a randomized experiment, comparing childbirth rates between vaccinated and unvaccinated women. Cox proportional hazards models were applied, treating vaccination as a time-varying covariate. Causal modeling was used to adjust for potential bias. To capture vaccine effects on both conception and established pregnancies, the index event was set at an estimated conception date, 280 days prior to childbirth.
Results
We show that with an assumed average pregnancy length of 280 days, there are no statistically significant associations between COVID-19 vaccination and childbirth (unadjusted HR = 0.94 (95% CI 0.89-1.00); adjusted HR = 1.03 (95% CI 0.97-1.09). Assuming a shorter pregnancy length (266 days), the associations between vaccination and childbirth remain insignificant (unadjusted HR = 0.96 (95% CI 0.90-1.02); adjusted HR = 1.04 (95% CI 0.98-1.11)). Neither are there statistically significant associations between COVID-19 vaccination and recorded miscarriages (unadjusted HR = 0.84 (95% CI 0.69-1.03); adjusted HR = 0.86 (95% CI 0.70-1.05).
Conclusions
COVID-19 vaccination is not associated with a decrease in childbirth after adjusting for common confounding factors. These findings provide evidence to support vaccination policies for women of childbearing age.
Plain Language Summary
Early, unfounded rumors spread during the COVID-19 pandemic claimed that mRNA vaccination could cause infertility. Later, suspicions were raised regarding whether reductions in childbirth observed during the pandemic were associated with the novel COVID-19 vaccines. We therefore study effects of COVID-19 vaccination in a representative population of Swedish women, and adjust for any confounding effects. No association is observed between COVID-19 vaccination and childbirth, or between vaccination and recorded miscarriages. We thus find no evidence for any connections between COVID-19 vaccination and the observed decrease in childbirth. Our results are relevant for consideration when vaccination policies involving women of childbearing age are determined.
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Data availability
The data that support the findings of this study are available on reasonable request five years after article publication from the corresponding author [toomas.timpka@liu.se]. The data are not publicly available due to Swedish legislation. Source Data for Fig. 2 is provided as Supplementary Data.
Code availability
The R code required to replicate our results is available from GitHub at https://doi.org/10.5281/zenodo.18138478.
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Acknowledgements
This study was supported by grants from the Swedish Research Council (VR 2021-05608, VR 2022-05608, VR 2025-06721), Region Östergötland (ALF-936190), and the Research Council of Southeast Sweden (FORSS-940915).
Funding
Open access funding provided by Linköping University.
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D.N., T.S., and T.T. conceived and designed this study; D.N. analyzed the data; A.S., O.E., J.L., Ö.D., and T.T. verified the results; D.N. and T.T. wrote this paper; T.S., O.E., J.L., A.S., J.H., M.B., D.A., E.G., and Ö.D. revised the manuscript and provided intellectual content. T.T. is the guarantor of the content.
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Nordvall, D., Schön, T., Hinkula, J. et al. COVID-19 vaccination carries no association with childbirth rates in Sweden. Commun Med (2026). https://doi.org/10.1038/s43856-026-01396-x
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DOI: https://doi.org/10.1038/s43856-026-01396-x
