It’s confirmed: Covid-19 vaccines disrupt the menstrual cycle

A rather reassuring conclusion on the effects of the vaccine against Covid-19Covid-19 on menstruation just appeared in the journal Science. This is an article entitled “Perspectives”, written by Victoria Male, Professor of digestiondigestion and of metabolismmetabolism at theImperial College from London. After analyzing several studies on the subject, the scientist reports that the vaccinationvaccination against Covid-19 causes slight changes in menstruation, but which most often disappear in just two cycles.

Elements of previous reports

Victoria Male recalls that women around the world have reported changes in their menstrual cyclemenstrual cycle after vaccination against Covid-19, such as heavier bleeding and increased durationduration of the menstrual cycle. For example, the Vaccine Adverse Event Reporting System of the United States received more than 11,000 reports of unexpected menstrual changes and vaginal bleeding after vaccination last April.

A study of data from nearly 4,000 women — residing in the United States and users ofapplicationapplication menstrual cycle tracker Natural Cycles — found that there was no effect of the first dose of vaccine, that the second dose was associated with an increase in cycle length of 0.45 days, and that administration of both doses of vaccine during the same cycle was associated with an increase of 2.32 days.

Another study found that heavier than normal bleeding was most often associated with vaccination. This was the case for 13.6% of participants for the period after vaccination, against 7.6% for the period before vaccination. In contrast, there is ample evidence that vaccination against Covid-19 does not affect fertility.

Two overriding assumptions

As the type of vaccine does not seem to influence this change in menstruation, the effect would result from the immune responseimmune response to vaccination, rather than a specific component of the vaccine. Indeed, menstrual changes have already been reported with vaccines against typhoid,Hepatitis BHepatitis B and human papillomavirus (HPV).

If we still do not know with certainty why the menstrual cycle is disturbed, two hypotheses are retained: “ Innate immune responses may transiently interfere with hormonehormone that govern the menstrual cycle, or they could affect macrophagesmacrophages and natural killer cells mucosamucosa of the’uterusuteruswhich control the degradation and regeneration of this tissue during the cycle writes Male in his post. Furthermore, the timing of vaccination in the menstrual cycle would have a impactimpact on increasing cycle time. Thus, longer cycle length would only be associated with vaccination during the follicular phase of the cycle, which occurs before theovulationovulation.

The second hypothesis of immune cells affected by vaccination against Covid-19 is supported by the fact that increasing age was associated with an increased risk of heavier bleeding. ” This could suggest that impaired tissue repair, which is mediated by immune cells in the uterus and which may be less effective in older people, is the mechanism by which vaccination with Covid-19 increases menstrual flow. “explains the professor.

In order to identify with certainty the pathways involved, she believes that further studies that track hormone levels in the blood before and after vaccination, as well as studies of immune cells isolated from biopsiesbiopsies endometrial or liquidliquid menstrual are justified.


Does the Covid-19 vaccine change the length of the menstrual cycle?

Article of Stephanie LeGuillouStephanie LeGuilloupublished on January 7, 2022

Rumors are circulating about potential adverse effects of anti-Covid vaccines on the menstrual cycle of women. A scientific study was conducted to explore the issue. It was published this Thursday, January 6 in the journal Obstetrics and Gynecology. Decryption.

The study published in the journal Obstetrics and Gynecology is based on the collection of data from a menstrual cycle tracking application, from October 2020 to September 2021. Four thousand women were included in the trial, aged between 18 and 45 years. These women had regular cycles of normal length (between 24 and 38 days). Among them, 2,500 were vaccinated with Pfizer-BioNtech, Moderna or Janssen, while the others were not vaccinated. The women’s cycle length was analyzed for six consecutive months. For the group of vaccinated women, follow-up started three months before vaccination and ended three months after vaccination.

A lengthening of the cycle following vaccination of less than one day

In the group of vaccinated women, the menstrual cycle following the injection was lengthened by less than a day (0.75 days) while the menstrual cycle of the unvaccinated women was not lengthened.

A variation in the length of the menstrual cycle of less than eight days is not abnormal

To put this delay into context, it should be noted that the International Federation of GynecologyGynecology and Obstetrics considers that a variation in the duration of the menstrual cycle of less than eight days is not abnormal. Indeed, while some women have extremely regular cycles, others can observe huge variations from cycle to cycle. Moreover, there was no longer any difference between the two groups at 2e cycle following vaccination. Some women reported delays of more than eight days in both groups, with no significant difference. Women who received two injections during the same cycle (n=358) experienced an increase in cycle length of almost two days, an effect which disappeared during the second cycle after the injections.

A known effect

A minimal and temporary prolongation of the length of the menstrual cycle in women had already been observed after vaccination against human papillomavirushuman papillomavirus. As a reminder, this vaccine protects against cervical cancerscervical cancers caused by sexually transmitted human papillomaviruses. This vaccine is recommended in France for all children (girls and boys) between 11 and 14 years old. Catch-up is possible between the ages of 15 and 19. In addition, another study reported that infection with SARS-CoV-2 led to an extension of the duration of the menstrual cycle in a quarter of infected women.

Other rumors circulate about a possible negative effect of vaccines on female fertility. The data available to date show no impact of vaccination on fertility in either women or men.

On the other hand, a Covid-19 infection in a pregnant woman increases the risk of miscarriage or premature birth. In conclusion, if you are a woman who wants to have a child, know that the vaccine has no impact on your fertility. On the other hand, being infected with SARS-CoV-2 during the pregnancypregnancy may interfere with its smooth running.


Do Covid vaccines really affect fertility and menstruation?

Vaccines can cause infertility and affect menstruation. These assertions are regularly shared on social networkssocial networks. What does the scientific community say?

Article of Julie KernJulie Kernpublished on August 27, 2021

These are rumors that die hard. They spread on social networks or during discussions with family or friends. Anti-Covid vaccines would make women sterile and disrupt the menstrual cycle.

How does the scientific community respond to these concerns that can deter women of childbearing age, especially the youngest, from getting vaccinated?

Do vaccines make women sterile?

The theory that vaccination or infection with SARS-CoV-2 could cause infertility is based on the presumed similarity between the proteinprotein S of SARS-CoV-2 and syncytin-1. Syncytin-1 is encoded by a retrovirusretrovirus endogenous human (HERV), a gene inherited from a retrovirus that has taken up residence and stabilized in the genomegenome of our ancestors, millions of years ago. This protein plays a fundamental role in the formation of the placenta.

Thus, some people think that the antibodyantibody specific for protein S, whether related to natural infection or vaccination, can also recognize syncytin-1 and destroy it. If this cross-neutralization occurs, it would cause sterility.

However, as indicated this study published on June 2, 2021, this theory could not be proven by rigorous scientific experiments. No alteration of the implantation of theembryoembryo in pregnant women vaccinated or infected with Covid-19 has been observed, in comparison with seronegative women.

Do vaccines disrupt the menstrual cycle?

A second rumor spread from real and valid testimonies. On TwitterTwittermany women have reported problems with their period after vaccination: longer or shorter, heavier or lighter, more painful or suddenly irregular.

These experiences do not appear to be a consequence of vaccination. Other factors can explain these very common variations, and most of the time transitory. The first is undoubtedly the stressstress related to vaccination. But there is also fatigue or a change in lifestyle.

In a report published in early Augustthe Pharmacovigilance Risk Assessment Committeea committee responsible for pharmacovigilance issues for the European Medicines Agency, found no causal link between Covid vaccines and menstruation disorders, reported by many women.

Nevertheless, they are to be watched. If menstruation problems persist over time or worsen, they may be synonymous with a more serious condition such asendometriosisendometriosis or the formation of uterine fibroids.

These two rumors are therefore not based on verified scientific data, like many medical publications that go viral on social networks.

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