COVID vaccination not linked to reduced childbirth

COVID-19 vaccination is not the cause behind a decrease in childbirth, according to a study from Linköping University, Sweden. The results speak against rumours about vaccination and reduced fertility. The findings have been published in the journal Communications Medicine.

"Our conclusion is that it's highly unlikely that the mRNA vaccine against COVID-19 was behind the decrease in childbirth during the pandemic," says Toomas Timpka, professor of social medicine at Linköping University.

The researchers investigated the issue because, since the beginning of the COVID-19 pandemic, unfounded rumours have circulated, especially on social media, alleging that vaccination impairs chances of becoming pregnant. In the later stages of the pandemic, there was a decrease in the number of children born in some countries, including Sweden. This raised the question whether this could be due to the new vaccines.

In the study, the researchers analysed all women aged 18 to 45 years in Region Jönköping County, a total of almost 60,000 women (of the region's total population of 369,000 people). Of these women, 75 per cent were vaccinated once or more against COVID-19 from 2021 to 2024. The researchers used data on childbirths, vaccination, miscarriages and deaths from healthcare records.

When the researchers compared childbirths and miscarriages between vaccinated and unvaccinated women, they found no statistically significant difference between the groups. This is in line with several previous studies that have not found any association between COVID vaccine and fertility.

"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," says Toomas Timpka.

The researchers believe that the decrease in childbirth has other, more likely explanations. Those who are now in their 30s, an age when it is most common to have children, were born in the second half of the 1990s. This was a time of financial difficulties and declining childbirth rates in Sweden. In other words, the group of current potential parents has become smaller due to declining birthrates 30 years earlier. Also, factors linked to the pandemic may have reduced childbirth, such as health and economic concerns and changed behaviour during lockdown.

One of the strengths of the study is that it examines pregnancy outcomes in a large group that is representative of the country's population. The researchers have taken into account that the woman's age is a possible factor that could hide a possible effect of vaccines on childbirth, and they have therefore compensated for age in their analysis.

The study received financial support from, among others, the Swedish Research Council.