A vaccination against the coronavirus can lead to a slightly longer menstrual cycle, but the disruption is minimal and disappears quickly. This is according to an American study of 4000 women.
The study is published in the scientific journal Obstetrics & Gynecology . The researcher surveyed both vaccinated and unvaccinated women. The vaccinated women were followed three cycles before their shot and three cycles after their shot, in order to accurately map the effects of vaccination on the menstrual cycle.
The women tracked their cycle via an app and shared that data with the scientists. It showed that the mean change after vaccination was just under one day. Abnormalities often resolved within the first full cycle after vaccination.
The menstrual cycle runs from the first day of your period up to and including the last day before the start of the next menstrual period. The exact length of this period varies per woman, but lasts an average of 28 days.
Lead researcher Alison Edelman calls the research results reassuring . “We don’t see any cause for concern about reproductive or physical health, for example.” The slightly longer cycle is labeled as “clinically irrelevant” in the study.
The researchers did see a greater effect in women who received both vaccinations in one cycle. Their cycle lasted about two days longer on average; according to scientists, this may indicate that the immune response that the vaccine elicits has an effect on the cycle. At the same time, they emphasize that many other factors can influence the menstrual cycle that are not related to vaccination, such as stress or illness.
This study says it’s not because of the vaccination, it’s just the usual variation.
Gynecologist Marlies Bongers about a changed cycle after vaccination
Gynecologist Marlies Bongers, who is a doctor at the Máxima Medical Center and a professor at Maastricht University, calls the American research “good and extensive”. She particularly appreciates the fact that data collection has already started before the first injection.
“So you can really see what changed in the cycle,” Bongers said in Nieuws en Co on NPO Radio 1. “And then they also compared it with a group that had not been vaccinated. There are women who, after a vaccination were worried because they were a week late or missed a period. But this study says it’s not because of the vaccination, it’s just the normal variation.”
17,000 notifications
The possible effect of corona vaccination on the menstrual cycle is causing a lot of unrest. For example, until 1 December last year, side effects center Lareb received more than 17,000 reports of menstrual disorders after vaccination against the corona virus. This involved a variety of complaints, such as heavy or delayed menstruation.
Since the summer, the center has been conducting follow-up surveys among 2000 reporters. Follow-up questions are asked about the nature of the complaints at the time in the cycle that they occurred. It is unclear when the results of that follow-up study will be published.
Lareb close the relationship between menstrual disorders and vaccination not , but stresses that there is no evidence that vaccines have a negative impact on fertility example. That fear of infertility appears to be persistent, NOS Stories pointed out at the end of last year via a questionnaire that was completed by more than 2,700 young people.
According to gynecologist Marlies Bongers, the recent American research is an extra reason not to fear infertility after vaccination. “Because so far there is no study that has shown that women become less fertile and it now seems that you ovulate at the same time. They also looked at women between 24 and 45 years, i.e. the age at which women typically want to get pregnant.”
According to her, this does not mean that everything around menstruation and vaccination has now been investigated. For example, Bongers considers it a missed opportunity that the American scientists did not immediately look at things such as the intensity of menstruation or changes in blood loss.
The American researchers write that they will look into this in a follow-up study. Bongers awaits the results with curiosity. “Because that has not been sorted out now and can also play a role.”
Report by NOS
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https://nos.nl/artikel/2412346-groot-onderzoek-vaccin-heeft-miniem-effect-op-menstruatiecyclus
