This is how the corona vaccination affects the period

Especially in social networks, women report that they have noticed changes in their cycle or bleeding intensity as a result of the corona vaccination. Some women observed heavier and more painful bleeding, others a changed cycle rhythm. Why vaccination can affect the cycle and how these changes affect it.

This is how the corona vaccination influences the cycle

American experts analyzed anonymous data from a fertility app from 2,400 vaccinated and 1,500 unvaccinated women aged 18 to 45. The majority of the vaccinated test subjects received the  mRNA vaccine  from BioNTech/Pfizer (55 percent), followed by  Moderna  (35 percent) and  Johnson  & Johnson (7 percent), with around another three percent not knowing the vaccine.

A total of three cycles before and three cycles after vaccination were evaluated and compared to the six consecutive cycles of unvaccinated women. The results show only slight changes in the cycle:

• After the first dose, the cycle lengthened by about 0.64 days on average.
• After the second vaccination, the cycle was delayed by about 0.79 days.
• Two vaccinations with BioNTech/Pfizer or Moderna in the same cycle could delay the bleeding by two days on average.

No data are known for the booster vaccination.

The study does not confirm previous rumors from social networks. The corona vaccination has only a minor effect on the female cycle. The specialist society International Federation of Gynecology and Obstetrics classifies cycle changes of less than eight days as normal. Cycle length and the strength of the period can vary over time, factors such as diet, exercise and physical and mental  stress  also influence the cycle.

cycle is sensitive to stress

The female cycle naturally fluctuates and is generally very sensitive to stress. The body releases sometimes more, sometimes less hormones that regulate the cycle. This can lead to premature or delayed menstruation, which can also be weaker or stronger. Cycle changes are not uncommon at first.

It is known that women who want to have children often document their cycle very meticulously and then also notice more abnormalities that they may not have noticed before.

These mechanisms also seem to take effect after the vaccination: On the one hand, the vaccination can cause stress in the body because the person to be vaccinated is excited or anticipatory beforehand. On the other hand, it may be that the woman observes the cycle more closely after the vaccination and the changes are more noticeable.

According to experts, however, there is no reason to worry that the vaccination will change the cycle in the long term. Also with regard to fertility, contrary to what is often stated, no restrictions are to be expected from the corona vaccination.

Corona vaccination: reaction of the immune system responsible for altered cycle

A strong immune system reaction could be partly responsible for the slight cycle changes. Among other things, it influences the connection between the hypothalamus, the  pituitary gland  and the ovary – and thus the production of hormones.

In addition, the production of cytokines (inflammatory proteins) can also affect the cycle. The timing of the vaccination is also important here. Women who were vaccinated in the follicular phase (day one of menstruation until ovulation) were affected more often.

Women and men have different side effects

In gender medicine, which deals with different symptoms and therapies in women and men, it has long been known that some diseases trigger symptoms that differ in men and women. This may have something to do with the different hormonal situation of the sexes.

There also seem to be differences in the side effects related to vaccination against  COVID-19  : three quarters of the side effects reported to the Paul Ehrlich Institute so far affect women.

Most of these side effects, such as  headaches , fatigue or pain at the injection site, are harmless and disappear within a short time. The  COVID arm  as a side effect is also significantly more common in women.

The Paul-Ehrlich-Institut has so far not reported any significant increase in menstrual cycle changes in women.