Disruption of menstruation, risk of becoming infertile: a look at what is and is not known about the effects of the Covid-19 vaccine. (Photo: Matic Zorman/Maison Moderne/archives)

Disruption of menstruation, risk of becoming infertile: a look at what is and is not known about the effects of the Covid-19 vaccine. (Photo: Matic Zorman/Maison Moderne/archives)

While many women report that the Covid vaccine has an impact on their menstruation, studies have yet to explain the cause and effect relationship. There are also concerns that it may cause infertility. Current studies show the opposite, although there is no evidence to predict longer-term effects.

However, the benefits of the vaccination tip the balance towards inoculation, say the experts interviewed. 

Late or early, longer, painful or heavy... After receiving their Covid-19 vaccine, many women have noticed changes in their periods.

"We hear this in consultations," says Pit Duschinger, a gynaecologist in Ettelbruck and president of the Luxembourg Society of Gynaecology and Obstetrics (SLGO). He believes that this is still a minority, "of the order of 5%". Above all, it would be "reversible". He does not have any statistics but notes that in general "everything disappears after half a year". Rosa Padovano and Marc Peiffer, gynaecologists in Luxembourg, confirm similar returns from patients in consultation. This only concerns a "small percentage".

More than 3,000 reports in France, no figures in Luxembourg

In France, the National Agency for the Safety of Medicines and Health Products (ANSM) has identified 3,870 cases of menstrual disorders reported after vaccination with the Pfizer-BioNTech vaccine and 562 with the Moderna vaccine, according to its latest update published on 21 December and covering the period from 26 November to 9 December 2021. It details that these were either more or less heavy bleeding, delayed periods or no periods at all. "These effects occurred both after the first injection and after the second. Most of them are not serious, short-lived and self-limiting events,” says the ANSM. The Belgian Federal Agency for Medicines and Health Products (FAMHP) also reports menstrual disorders after the administration of the vaccine, without being able to establish a cause and effect relationship. Studies are underway on the subject.

In Luxembourg, the latest pharmacovigilance report on the Covid-19 vaccine published on 17 December, for data dated 29 November, does not say whether adverse events related to menstruation are among the 2,016 reported since the start of the vaccination. When contacted, the Pharmacy and Medicines Division of the Health Directorate did not respond to Delano’s sister publication Paperjam.

A direct or indirect link

How can a vaccine potentially affect menstruation? "It remains an enigma," admits Pit Duschinger. In the meantime, he prescribes anti-inflammatory drugs to his patients with painful periods, "as for any treatment of non-vaccine related dysmenorrhoea". Gynaecologist Marc Peiffer guesses: "During menstruation, inflammatory phenomena are greatly increased.” This could be the reason why women who are vaccinated at the time of their menstruation experience disturbances. Even for those who receive their dose outside this period, "the reactions differ from one person to another, some will have a headache for a few days, others for several weeks. So it may well be that a woman who was not vaccinated during her period will feel the impact during her next period." He points out that this refers to natural periods, not artificial ones, caused by the pill.

I don't see how this could affect fertility.

Marc Peiffergynaecologist

On her website, puts forward several hypotheses. One is that it has an impact on the "chemical messaging from the brain to the ovaries", on the "chemical messaging from the ovaries to the uterus" or on the endometrium. It could also come from the "immune system response to the vaccine" or from "vaccine-related stress". Duschinger adds that "a large number of side effects are made public because hundreds of thousands of people are vaccinated at the same time".

Other vaccines have been suspected of affecting menstruation. In a 2015 report, the European Medicines Agency (EMA) noted several reports of "menstrual abnormalities" after vaccination against human papillomavirus (HPV), although a study in Japan did not find a direct link.

No proven impact on fertility

Another question that worries some people, even deterring them from getting vaccinated, is whether it will affect fertility. I don't see how it could affect fertility," says Peiffer. "There are no repercussions, enough big studies show that," adds Duschinger. On its website, the French National Institute for Health and Medical Research (Inserm) cites several such studies. One of them, conducted on 36 couples and published in May 2021, concludes that there is no effect on ovarian performance or embryo characteristics during in vitro fertilisation. Another, published in Jama Network in June, compared the sperm of 45 healthy men before and then more than 70 days after their second dose of the vaccine. It found no effect on these parameters either. These data are "few in number, but very reassuring", according to the Institute.

Two doctors had reported that the antibodies produced by the vaccine could make women infertile because they attacked a protein involved in the formation of placenta. "This has been shown to be false," rejects Duschinger. Several experts spoke of a very low probability , explaining that even if this were the case, the antibodies would not last long. found no more placental abnormalities in the group of 84 vaccinated pregnant women than in the control group of 116 women without the vaccine.

More benefits than risks

The vaccine does not therefore appear to affect fertility, according to the current data. But can we be sure that this will always be the case, even in the long term? "If there are after-effects, we will know in a few years' time," says Rosa Padovano. "I don't think we can expect any impact on fertility," reassures Peiffer.

I don't hesitate for a second and advise vaccination.
Pit Duschinger

Pit DuschingerPresidentLuxembourg Society of Gynaecology and Obstetrics

"We can ask this question for everything. In medicine, we will never be able to say with 100% certainty that there is no danger," admits Duschinger. He takes the example of paracetamol, which has been considered safe for years to relieve the pain of pregnant women, but has recently been called into question. Several experts signed in September in which they listed several possible effects on the foetus and called for its use in pregnant women to be avoided, pending further studies on the subject.

Despite this, "I do not hesitate for a second and advise vaccination" against Covid-19, maintains the gynaecologist. If some people fear that the vaccine will prevent them from having a child, they can also worry about the effects of a Covid-19 infection, he adds. "There are no exact statistics on this, and it will have to be observed after the crisis is over.” Pregnant women, who were initially excluded from the first waves of vaccination because they had not been involved in the clinical trials, were even considered a priority in the Luxembourg campaign, as in other countries. "We don't know why at the moment, but a pregnant woman is more likely to get sick if she gets Covid.” But she is not more likely to be infected, according to the gynaecologist. The Higher Council for Infectious Diseases (HCID) points to a higher risk of premature delivery or miscarriage in case of infection. There is even evidence to suggest that vaccinated pregnant women pass on their antibodies to their babies. The same applies to breastfeeding. It is not known for how long.

This story was first published in French on . It has been translated and edited for Delano.