COVID-19 vaccination is unlikely to be responsible for the decline in childbirth observed during the pandemic, according to a new study by researchers at Linköping University in Sweden.

“Our conclusion is that it’s highly unlikely that the mRNA vaccine against COVID-19 was behind the decrease in childbirth during the pandemic,” said Toomas Timpka, Professor of Social Medicine at Linköping University.

Since the onset of the pandemic, unsubstantiated claims have circulated suggesting that COVID-19 vaccination could reduce the chances of becoming pregnant. A subsequent decline in birth rates in several countries, including Sweden, prompted questions about whether newly introduced vaccines could be a contributing factor.

To investigate, researchers analysed data from nearly 60,000 women aged 18 to 45 in Region Jönköping County, which has a total population of about 369,000. Of the women included in the study, 75 per cent received at least one dose of a COVID-19 vaccine between 2021 and 2024.

Using healthcare records, the team examined data on childbirths, miscarriages, vaccinations and deaths. The analysis found no statistically significant differences in childbirth or miscarriage rates between vaccinated and unvaccinated women.

“We see no difference in childbirth rates between those who have taken the vaccine and those who haven’t. We’ve also looked at all registered miscarriages among those who became pregnant, and we see no difference between the groups there either,” Timpka said.

The findings are consistent with several previous studies that have found no association between COVID-19 vaccination and reduced fertility.

Researchers suggest that other factors are more likely to explain the decline in births. Women currently in their 30s — the age group most likely to have children — were born in the late 1990s, a period marked by economic challenges and falling birth rates in Sweden. As a result, the pool of potential parents has been smaller. In addition, pandemic-related factors such as health concerns, economic uncertainty and behavioural changes during lockdowns may have influenced family planning decisions.

The study’s authors noted that one of its strengths is the large and population-representative sample. They also adjusted for age in their analysis to account for its potential influence on childbirth rates.

The research was supported financially by the Swedish Research Council, among other funders.