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26th Dec 2021

Period irregularities ‘most likely’ caused by Covid vaccine, new study finds

Trine Jensen-Burke

Period irregularities most likely caused by Covid vaccine

“There are sufficient numbers of women who are experiencing changes, not just in Norway, but also abroad, to make it likely that this is connected to the vaccine.”

According to a brand new Norwegian study, there seems to be a link between the Covid-19 vaccine and certain period changes some women have experienced.

Speaking to Norwegian TV2, Gunnveig Grødeland, a highly regarded vaccine researcher based at the University of Oslo and Oslo University Hospital, explains that by looking at statistics, it can seem like the vaccine has indeed caused period changes in some women – but Grødeland doesn’t think these sudden changes will lead to any permanent changes and still recommends everyone eligible to get vaccinated.

The Norwegian institute of public health, the NIPH, are currently conducting a study in order to find answers to what might be the cause of the period irregularities. According to, the NIPH say that nothing suggests that the irregularities are dangerous or that they will lead to permanent change. Grødeland agrees with this assessment.

“Women experience irregularities but will return to normal after some time. So far there is nothing to suggest that this is more than a change which will pass”, she explains.

However – we should still take these changes seriously, Grødeland cautions.

“It is an unpleasant experience, and it’s important to try to understand why it is happening. As of now, we don’t know a lot about possible causes. But when so many are experiencing it, we have to try and find the biological explanation”, she says.

Heavy and extended bleeding

Norweigan TV2 recently asked their audience whether or not they had experienced changes in their periods after getting a corona vaccine – and were overwhelmed by the response. More than 200 women came forward and shared their stories, ending in a series of articles on the topic.

Of the 200 women, 70 per cent experienced changes in their menstrual cycle. 55 per cent experienced heavier bleeding, while 53 per cent experienced prolonged bleeding. Just over 40 per cent of the women experienced heavier menstrual pains.

One woman did not get her period for a month and a half, only to be hit with ‘extreme amounts of blood and heavy pains’ when it finally arrived. Another woman said her gynaecologist could see that her ovaries were active again, despite having gone through menopause years ago.

The Norwegian Medicines Agency has filed more than 1200 reports on menstrual irregularities after the Covid vaccination program kicked off, and according to, 99 of them are classified as serious, meaning the woman ended up in hospital or experienced great discomfort.

“This is unusual. We have never received reports on menstrual irregularities connected to a vaccine before”, Sigurd Hortemo from the Norwegian Medicines Agency says.

Too early to conclude anything

Norwegian professor and immunologist Anne Spurkland has also spoken about menstrual irregularities.

She, however, believes it is too early to conclude that there is a connection between the vaccine and the menstrual problems but acknowledges that the timing of the vaccine and subsequent menstrual irregularities is striking.

“The fact that almost all of us are having this vaccine within the same short timeframe makes it easier to discover that some women are experiencing menstrual irregularities after the vaccine”, Spurkland says.

The professor says that it may not be unusual to experience menstrual changes following an infection with other viruses, like the flu. However, only a smaller part of the population will get the flu, and the women who may have this side effect may not think too much of it, as they are alone in experiencing it.