Disrupted periods and Covid-19 jabs: is there a connection?

Some kind of “period weirdness” is “afoot”, and a growing number of people believe that “Covid-19 vaccines could have something to do with it”.

So claims journalist Annaliese Griffin in an article for The Cut, before citing anecdotal evidence that women have experienced changes to their menstrual cycle after being inoculated against coronavirus.

“I’ve heard about super-heavy periods, nonexistent periods, puzzling weight fluctuations, increased acne and new chin hairs,” wrote Griffin. And while anecdotal evidence “doesn’t exactly count as science”, she added, “it’s all we’ve got”.

Subscribe to The Week

Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.

SUBSCRIBE & SAVE

Sign up for The Week's Free Newsletters

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

Sign up

But that could be set to change. A newly published report in the British Medical Journal by Dr Victoria Male, a lecturer in reproductive immunology at Imperial College London, said that a link between menstrual changes and the Covid-19 vaccine is “plausible and should be investigated”.

As Male pointed out, more than 30,000 reports of post-vaccine menstrual disorders have been recorded by the UK Medicines and Healthcare Products Regulatory Agency (MHRA).

According to the government agency, “suspected reactions relating to a variety of menstrual disorders have been reported after all three of the Covid-19 vaccines” in use in the UK - Pfizer, AstraZeneca, or Moderna. And changes “including heavier than usual periods, delayed periods and unexpected vaginal bleeding” have been recorded after both the first and second doses of the jabs.

Other experts have joined Male in calling for research into the possible link. Dr Raj Mathur, a consultant in reproductive medicine and the chair of the British Fertility Society, told the Daily Mail that it “does appear” that “some women” experience “a transient disturbance in the menstrual cycle” after having the vaccine.

But the MHRA doesn’t support the theory. “The number of reports of menstrual disorders and vaginal bleeding is low in relation to both the number of people who have received Covid-19 vaccines to date and how common menstrual disorders are generally,” said the agency, which added that there was no evidence that the jabs have an adverse effect on fertility.

“Millions of British women have been jabbed”, wrote Lara Prendergast at The Spectator, so yes, these reports clearly amount to a “negligible number”.

But “it doesn’t seem negligible if you’re one of those women”, she continued, and “the real number of cases in the UK is possibly quite a bit higher”.

Talking about “what the jab has done to our periods” in public can feel “awkward”, but these conversations have been “going on discreetly, on WhatsApp chats, on internet threads, in hushed tones”.

In May, when a total of around 20 million people in the UK had been fully vaccinated, the BBC reported that “women online around the world have started asking if early, heavy or painful periods might be an unlisted reaction to the jab”.

Dr Male told the broadcaster that “there’s an issue here about how often women’s health is ignored”. She emphasised that there was “masses of evidence” that the menstrual cycle changes were temporary and don't affect fertility.

But in her newly published report, she argued that further research is needed into the “biologically plausible mechanisms” that may trigger the disorders. If there is a connection, she wrote, “it is likely to be the result of the immune response to vaccination rather than a specific vaccine component”.

Sex hormones and immune systems are closely linked, Male explained during an interview on BBC News, so if your immune system experiences a “big shock” - caused by a vaccine, or an infection itself - there may be changes to “when and how you bleed”.

The uterus is also lined with a lot of immune cells, which may be impacted by the “general activation of your immune system”, in turn affecting the menstrual cycle.

The theory that vaccines may disrupt menstrual cycles in by no means new. Indeed, doctors have been pointing to the possible link for more than a century.

Shortly before the outbreak of the First World War, for example, a US doctor published a report about how typhoid vaccines appeared to affect menstruation.

Yet such changes continue to be overlooked during most clinical trials. “In fact, in many trials, women are wholesale excluded because of potential menstrual cycle effects,” wrote author and feminist campaigner Caroline Criado-Perez in an article for The Telegraph, “so perhaps we should be grateful for small mercies that they were included at all” in those for Covid jabs.

“Still, enough women have now reported menstrual cycle effects that the issue has become impossible to ignore,” she continued. The US National Institute of Health (NIH) last month announced that $1.67m (£1.2m) had been allocated to research the link between menstrual changes and Covid vaccines. But while the funding is “hugely welcome”, it’s “too late for many of us”, said Criado-Perez.

As Griffin noted in The Cut, “medicine has a long history of telling women who report physical symptoms that it’s all in our heads”.

“Nobody wants to be thought of as hysterical. Emotional. A tad neurotic,” added Prendergast in The Spectator.

Women’s concerns about the possible effects of Covid jabs have also been dismissed in “a well-meaning but ultimately misguided effort to reduce vaccine hesitancy in young women”, wrote Criado-Perez. But “unlike the medical gaslighting approach”, research to find out what is going on “may actually convince some vaccine hesitant women to get their jab” and “could also form a basis for future, much-needed research on the interaction between the menstrual cycle and the female immune system”.

In the meantime, experts including Male are urging doctors to encourage women in the UK to report post-jab menstrual changes to the MHRA.

“This will provide more complete data to facilitate research into any link and signal to patients that their concerns about vaccine safety are taken seriously, building trust,” wrote Male in her BMJ report.