After vaccination against Covid-19, the menstrual cycle can be lengthened by almost a day

A study shows that the Covid vaccination is associated with a small temporary increase in the length of the menstrual cycle.

On health, this American study carried out by researchers from Oregon Health & Science University (Portland) and published in the journal ‘Obstetrics & Gynecology’ shows that no undesirable incidence is to be noted. Indeed, some women present a menstrual cycle lengthened by one day following being vaccinated. Remember that these upheavals remain a priori ‘temporary’.

The authors found that women vaccinated (either with Pfizer, Moderna or Janssen) had an average delay of just under a day (approximately 0.75 days) in the cycle following the vaccine injection.

The observed increase remains within the range of normal variability

One of the authors of this study, Dr Alison Edelman, adds that menstrual cycles may vary slightly from month to month and the observed increase remains within the range of normal variability.

Researchers are continuing their research to find out the mechanism by which vaccination Covid-19 might influence other menstrual characteristics, such as associated symptoms (pain, mood changes, etc.) and bleeding characteristics. The results let women know what to expect from the pandemic vaccination, the study said.

No impact on fertility

In the columns of Science and the Future, American College of Obstetricians and Gynecologists Vice President Christopher M. Zahn adds: “This study shows that the impact of Covid-19 vaccines on menstruation is minimal and temporary. We continue to stress that vaccines have no impact on fertility. Women should feel confident in their decision to be vaccinated, and if eligible, be reminded“, He reassures.

For its part, the National Agency for the Safety of Medicines and Health Products (ANSM – France) specifies that ‘Menstrual disorders declared following vaccination with an mRNA vaccine are subject to careful monitoring. These effects occurred both following the first injection and following the second injection. Most of these are short-lived and self-limiting events. To date, the available data do not allow us to determine the direct link between the vaccine and the occurrence of these disorders of the menstrual cycle. These events remain under surveillance ”, it is indicated.