If you have been vaccinated against Covid-19 and have experienced a delay in period, it could be an after effect of the vaccine as found in a US government-funded study.

According to a report in the AFP, the study saw a slight delay of getting their periods in vaccinated women.

The delay is almost a day compared to unvaccinated women, with no changes in the number of days of bleeding.

When vaccination takes place has an impact too

Lead author Alison Edelman of the Oregon Health & Science University was quoted in the report as saying that the effects are small and expected to be temporary.

For the study, close to 4,000 vaccinated and unvaccinated women between the ages of 18 to 45 were roped in. The women were not using hormonal contraception.

The women’s data consisting of their six menstrual cycles was analysed from a fertility tracking app.

The study, that was published in "Obstetrics & Gynecology” linked the first vaccine dose with a 0.64-day increase in cycle length and the second dose with a 0.79-day increase, when comparing the vaccinated to unvaccinated group.

The report said this is most probably due to the immune system's response to the vaccine.

It added that the changes seem to be most pronounced when vaccination takes place early in the follicular phase of the menstrual cycle.

With the finding of the study, the team hopes to gather more data especially regarding subsequent cycles among vaccinated women and expand the study globally to differentiate the effects between vaccine brands.