Earlier this year we reported that a study had confirmed what many of us had long suspected – that getting vaccinated against COVID-19 can have an impact on your period, either causing it to arrive late, last longer or feel heavier/more painful. Thankfully, the side effects are short-lived, and now further research has found that your regularly scheduled period should resume after one menstrual cycle.
This latest research from the Department of Obstetrics and Gynecology, Oregon Health & Science University, published on Tuesday (27 September), uses a wide sample pool of almost 20,000 people (around 75% of whom have been vaccinated and 25% who have not). According to the British Medical Journal, it solidifies and provides sturdy evidence that cycles are altered post-jab and identified that these changes occur irrespective of which pharmaceutical company produced the vaccine a person received (e.g. Pfizer, AstraZeneca, Moderna).
As for how long people's cycles are increasing for, the new research suggests by 0.71 days following the first dose and 0.56 days after the second dose. For those who had multiple coronavirus-related jabs within the same menstrual cycle, the delay leapt up to four days.
Speaking about the phenomenon of the jab altering periods, back in January Dr Victoria Male, an expert in menstruation from Imperial College London, said the research is "reassuring", according to the BBC. "Changes to the menstrual cycle do occur following vaccination – but they are small compared with natural variation and quickly reverse," she explained. "[Concerns around fertility being impacted have arisen only] from misinformation that Covid-19 vaccines cause female infertility."
Earlier this year, one US-based study harvested data from close to 4,000 women who use a cycle-tracking app and found that on average, their period was delayed by half a day after their second dose, but there was no delay after the first. This came after more than 36,000 people reporting post-vaccine period irregularities to the MHRA Yellow Card scheme.
Another research project from Norway (of over 5,600 people) reinforced how much periods can also vary naturally – due to an array of reasons from diet changes, to stress. Nearly 40% of study participants reported at least one change to their period, even before being vaccinated, the most commonly noted change being heavier than normal bleeding.
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The study said that "menstrual disturbances were generally common regardless of vaccination" but that there was a "significant increase in menstrual disturbances after vaccination, particularly for heavier bleeding than usual, longer duration and for short interval between menstruations."
Anecdotally, others have reported that their period felt heavier and more painful for the first cycle after they contracted COVID-19.
This article is not intended to be a substitute for professional medical advice or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Jennifer Savin is Cosmopolitan UK's multiple award-winning Features Editor, who was crowned Digital Journalist of the Year for her work tackling the issues most important to young women. She regularly covers breaking news, cultural trends, health, the royals and more, using her esteemed connections to access the best experts along the way. She's grilled everyone from high-profile politicians to A-list celebrities, and has sensitively interviewed hundreds of people about their real life stories. In addition to this, Jennifer is widely known for her own undercover investigations and campaign work, which includes successfully petitioning the government for change around topics like abortion rights and image-based sexual abuse. Jennifer is also a published author, documentary consultant (helping to create BBC’s Deepfake Porn: Could You Be Next?) and a patron for Y.E.S. (a youth services charity). Alongside Cosmopolitan, Jennifer has written for The Times, Women’s Health, ELLE and numerous other publications, appeared on podcasts, and spoken on (and hosted) panels for the Women of the World Festival, the University of Manchester and more. In her spare time, Jennifer is a big fan of lipstick, leopard print and over-ordering at dinner. Follow Jennifer on Instagram, X or LinkedIn.
