Covid-19 vaccines affect menstruation, study shows


The study, which was published in the scientific journal, BMJ, vindicates more than 85 women who spoke to the Nation last year, complaining that their periods had delayed after taking the vaccines.

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Scientists have confirmed that Covid-19 vaccines temporarily tamper with women’s menstrual cycles.

The study, which was published in the scientific journal, BMJ, vindicates more than 85 women who spoke to the Nation last year, complaining that their periods had delayed after taking the vaccines.

At the time, their link of Covid-19 vaccines and menstrual cycles was based on speculation since no research had been done.

During the pandemic, the Pharmacy and Poisons Board, through the Health ministry, had asked people to report any possible side effects from the jab. However, no data on the side effects shared is publically available.

In the study, the researchers used data from a period-tracking mobile application called Natural Cycles and the participants were between the ages of 18 and 45.

They tracked users’ menstrual cycle about three months before vaccination and another cycle after vaccination making a comparison with those that did not receive the Covid-19 jab.

Vaccinated and unvaccinated

Using data of about 20,000 people, vaccinated and unvaccinated, the scientists found that those who were vaccinated had a small and likely temporary change in their menstrual cycle length.

However, it did not find any change in the number of days girls have their periods.

“Individuals who were vaccinated had a less-than-one-day adjusted increase in the length of their first and second cycles, compared with individuals who were not vaccinated,” said the study.

It showed that people who received two vaccine doses during the same cycle were likely to have delays of up to about four days before their menses began.

However, the study says this temporary change lasts only in one cycle and the subsequent cycle after vaccination is likely to revert to normalcy. There was no difference in the vaccine type that people used as the changes were observed across all the available jabs.

This study builds up to a previous small study conducted in the US earlier this year and their findings are the same.

“The vaccinated cohort experienced a less-than-one-day unadjusted increase in the length of their menstrual cycle during the first vaccine cycle compared with their three prevaccination cycles,” said the study.

“Menstrual cycle timing is regulated by the hypothalamic-pituitary-ovarian axis, which can be affected by life, environment, and health stressors. Our results cannot be explained by generalised pandemic stress because our unvaccinated control group saw no changes over a similar time period,” explained the researchers.

Commenting on the study findings at the United States National Institute of Child Health and Human Development, Dr Diana Bianchi said it is reassuring that the study found only a small, temporary menstrual change in women.

 “These results provide, for the first time, an opportunity to counsel women about what to expect from Covid-19 vaccination so they can plan accordingly,” said Dr Bianchi.

Starting puberty earlier

At a recent European Society for Paediatric Endocrinology conference, scientists from German also reported that more young women are starting puberty earlier than before and the number rose during the pandemic.

“Researchers at the University of Bonn, Germany, reported how the number of girls diagnosed with early puberty at a single medical centre remained constant between 2015 and 2019, at fewer than 10 cases a year. This more than doubled to 23 in 2020, when the Covid-19 outbreak took hold worldwide, rising further still to 30 in 2021, according to results presented,” reported an article published by the New Scientist.

Other studies show that there are public health impacts of early puberty, especially in girls.

“Children with early puberty are at a risk for accelerated skeletal maturation and short adult height, early sexual debut, potential sexual abuse, and psychosocial difficulties. Altered puberty timing is also of concern for the development of reproductive tract cancers later in life,” says a study.