People who received the Covid-19 vaccine reported slightly longer menstrual cycles, but the change was temporary, Addis said. Research It was published Tuesday in the journal BMJ Medicine.

“Compared to unvaccinated individuals, vaccinated individuals had an adjusted increase in menstrual cycle length of less than one day for both first and second vaccination doses,” wrote researchers from the universities of Oregon, Massachusetts, London, and Edinburgh. “Adjusted cycle length increased by 3.70 days in individuals who received two doses of the Covid-19 vaccine per cycle compared with those who were not vaccinated.”

The vaccinated group had a change in cycle length of about 0.71 days after the first dose, the authors said.

There was a “significant increase” in the proportion of responders who increased their cycle length by more than eight days, the authors said, with 13.5% of vaccinated individuals and 5% of unvaccinated participants reporting this.

“We found no difference in menstrual length in any group of vaccinated individuals,” the study says.

Changes in the length of the cycle did not remain in the cycle after vaccination, the authors – except for the group that received two doses in one cycle.

The changes appeared to be the same no matter which vaccine a person received.

The authors observed nearly 20,000 people, representing more than 250,000 cycles, who recorded their data through the Nature Cycles app between October 1, 2020 and November 7, 2021. For the vaccinated group, they looked at three pre-vaccination cycles and at least the first cycle of Covid. -19 dose cycle. For unvaccinated people, the same period included four to six cycles.

The participants come from many countries, but mostly from Europe and America and Canada. Nearly two-thirds of the 15,000 vaccinated participants received the Pfizer/BioNTech vaccine, although participants also received Johnson & Johnson, Moderna, and Oxford-AstraZeneca vaccines, among others.

“These findings provide more information to guide what to expect after vaccination,” said Dr. Diana Bianchi, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). News release. “Changes after vaccination appear to be small, within normal ranges, and transient.”

The study has some limitations, say the authors, including that people using hormonal birth control were not included, the researchers were limited in the number of post-vaccine cycles, and they were unable to account for the effects of potential infections in the participants.

The findings from A Early research Published by the same group of researchers focusing on women in the US.

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