UK: A recent study has found that the COVID-19 vaccine is not associated with abnormal menstrual cycle parameters. However, women with a history of COVID-19 disease were at higher risk of inter-menstrual bleeding, ‘missed’ periods, and heavier bleeding.
The study says the research reassures women who might have avoided vaccination because they were concerned about the impact on their periods.

Researchers from the Universities of Edinburgh, Montpellier, Oxford, Bristol and Exeter investigated results from a survey conducted in the UK in March 2021.
Participants were asked about any menstrual changes during the pandemic, their Covid-19 vaccination history and whether they had ever had Covid-19.
The researchers examined results from almost 5,000 pre-menopausal participants who had been vaccinated against Covid-19.
The vast majority-82 per cent-reported no menstrual changes. Only 6.2 per cent reported more disruption, 1.6 per cent reported less disruption, and 10.2 per cent reported ‘other changes’, which could refer to things like changes to cycle length and regularity or amount of menstrual bleeding.
Of the 18 per cent who reported changes, the risk was higher among those who smoked, previously had Covid-19 or were not using oestradiol-containing contraceptives such as the combined contraceptive pill.
The researchers then looked at a wider group of 12,000 participants, including vaccinated and unvaccinated against Covid-19.
Compared to those who were not vaccinated and had never had Covid-19, vaccination alone did not show increased abnormal menstrual cycle factors. However, those with a history of Covid-19 were at increased risk of reporting heavier bleeding, missed periods and bleeding between periods.
The study was conducted against the public concern that the Covid-19 pandemic had disrupted menstrual cycles due to vaccination, infection with the virus, and lifestyle changes.
There has been a lack of research into how much each factor has contributed to the changes and who is most at risk. Still, experts say this research provides valuable information about the understudied area of periods and Covid-19.
The team hopes that the results will help healthcare professionals when counselling women about the relative risks of menstrual disturbance when vaccinating against Covid-19, compared with having the infection itself, and also help women make decisions about Covid-19 vaccination.
Reference:
Alvergne, A., Kountourides, G., Argentieri, M.A., Agyen, L., Rogers, N., Knight, D., Sharp, G.C, Maybin, J.A, Olszewska, Z., A retrospective case-control study on menstrual cycle changes following COVID-19 vaccination and disease, ISCIENCE (2023), doi: https://doi.org/10.1016/j.isci.2023.106401.