Key Points
- There have been reports around the world of people's menstrual cycles changing after COVID-19 infections and vaccines
- While more research is needed, experts say there's a "probable" link between COVID and and changes to people's periods
People all around the world have reported changes to their periods after being infected with COVID-19 or getting vaccinated.
For some, the length of their cycle is different, while others have experienced changes to their flows, persistent bleeding, and increased pain levels.
Here's what experts know so far about why some people's menstrual cycles are different post-COVID, what changes are considered "normal", and when to seek help.
Is there proof COVID can cause changes to people's periods?
While anecdotal evidence shows large numbers of people who menstruate are experiencing changes to their cycle post-COVID infection or vaccine, researchers have so far struggled to definitively determine the main driver behind it.
Dr Mike Armour, senior research fellow in reproductive health at Western Sydney University, said that's because none of the studies conducted so far have used a control group of people who haven't been infected with COVID-19 or received a vaccine.
"That would really, obviously allow us to narrow down exactly what is it that's happening," he told SBS News.
Despite this, Dr Armour said there is enough evidence to suggest a "quite probable" link between COVID infection and vaccine, and changes to some people's periods.
There are two main hypotheses as to why this is happening, Dr Pav Nanayakkara, a specialist gynaecologist and advanced laparoscopic surgeon at Jean Hailes for Women's Health, said.
"It could be hormone-related, so either the vaccine or the infection is affecting the hormones, or the second mechanism is that it's immune-mediated so the inflammation in response to the vaccination may potentially cause immune changes in the uterine lining, which has the potential to then influence menstrual changes," she said.
"We know that women that are both on and off hormonal contraceptives do report changes, so it's less likely to be hormone-mediated, more likely to be inflammation."
Dr Pav Nanayakkara says changes people experience in their periods post-COVID infection tend to revert back to normal after a few menstrual cycles. Source: Supplied / Jean Hailes for Women's Health
"Inflammatory markers are a good predictor of things like premenstrual symptoms," he said.
"So I think what's likely is that both COVID itself and the COVID vaccine cause an inflammatory response."
What menstrual changes are considered 'normal'?
While everyone's period is "quite individual", Dr Armour said any menstrual cycle that varies in length between around 24 to 35 days is "pretty normal".
That means that if your period comes a few days earlier or later than it typically would after you've had COVID-19 or a vaccine, then you shouldn't be concerned.
Having a heavier or lighter flow than usual or experiencing higher levels of period pain are also commonly reported changes that you shouldn't be alarmed by, Dr Armour said.
"The key thing is that a lot of the people report that their changes then revert back to normal again after a few menstrual cycles," Dr Nanayakkara said.
"At this stage, it also doesn't look like there are any implications on fertility or pregnancy rates going forward."
When should I seek medical advice?
Dr Armour said anyone who experiences persistent pain, two or more weeks of continuous bleeding, or changes to the colour of their vaginal discharge should consult medical advice.
"I think it's better to be safe than sorry," he said.
"We don't want people to just brush it off as COVID-related."
Dr Mike Armour says there is enough evidence to suggest a "quite probable" link between COVID infection and vaccine and changes to some people's menstrual cycles. Source: SBS News / Insight
"It might be heavy bleeding, so you're soaking a pad an hour, passing large clots, or if you're noticing periods are more frequent, or you haven't had a period for a number of months, then it would be important to exclude some other causes that may contribute to those symptoms," she said.
"The worst thing is for you to sit at home suffering in silence, worrying, or using Dr Google when the help is out there to make sure that there's nothing that you should be concerned about."
Dr Nanayakkara said reaching out to your doctor if you experience menstrual changes could also help increase understanding about the impacts of COVID-19 infection and vaccination.
"At this stage, it appears that the risks are all very short-term in terms of changes to menstrual bleeding, but the only way we'll know is if you come forward," she said.
