COVID-19 Vaccination Does Not Affect Fertility or Pregnancy Outcomes, Study Finds
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A Swedish study found no statistically significant difference in childbirth or miscarriage rates between women who received COVID-19 vaccines and those who did not. Despite widespread misinformation during the pandemic suggesting vaccines could harm fertility, the findings provide reassuring evidence that COVID-19 vaccination does not negatively impact chances of pregnancy or pregnancy outcomes. The study was published in the Communications Medicine journal by Dennis N. and colleagues.
Women of childbearing age are hesitant to receive the COVID-19 vaccine due to widespread worries and conjecture that the vaccine may reduce childbirth or impair fertility. This study's main goal was to ascertain whether changes in Swedish women's childbirth rates are causally related to COVID-19 vaccination.
A large population-based cohort study was performed to mimic a randomized experiment. The study consisted of about 369,000 women from a representative Swedish population. The study compared vaccinated and unvaccinated women using Cox proportional hazards models, with vaccination as a time-varying exposure.
To reduce bias and improve causal inference, advanced causal models were used. To adjust for the impact of vaccination on both conception and existing pregnancies, childbirth was dated back to an estimated conception date, which was defined as 280 days before delivery. Sensitivity analyses were also performed using an average pregnancy duration of 266 days.
Key findings
In all the analyses, there was no statistically significant relationship found between COVID-19 vaccination and childbirth.
With a presumed pregnancy duration of 280 days, the unadjusted hazard ratio (HR) for childbirth was 0.94 (95% CI 0.89-1.00), and the adjusted HR was 1.03 (95% CI 0.97-1.09).
However, with a presumed pregnancy duration of 266 days, the results were similar, with an unadjusted HR of 0.96 (95% CI 0.90-1.02) and an adjusted HR of 1.04 (95% CI 0.98-1.11).
These results show that there was no significant reduction in childbirth among vaccinated women.
There was also no significant relationship found between COVID-19 vaccination and the recorded number of miscarriages.
The unadjusted HR for miscarriage was 0.84 (95% CI 0.69-1.03), and the adjusted HR was 0.86 (95% CI 0.70-1.05), showing that there was no increase in the risk of miscarriage among vaccinated women.
COVID-19 vaccination was not related to a reduction in childbirth or an increase in miscarriage after adjustment for common confounders. This large Swedish population-based study gives reassuring data that COVID-19 vaccines do not affect fertility or pregnancy outcomes, supporting current vaccination recommendations for women of reproductive age.
Reference:
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
