A new study has indicated that some COVID-19 vaccines may affect the length of a woman’s menstruation.
The research found that after getting a dose of the COVID-19 vaccine, some women’s menstrual cycles increased by one day longer than usual.
They noted that the average increase in the length of the menstrual cycle appeared to be driven largely by women who received doses of either Pfizer/BioNTech or Moderna within one menstrual cycle.
As reported by CNN, the researchers added that for this group of women, cycle length increased by an average of about two days. But the change was only temporary and resolved within a couple of months.
The study was conducted in the US and saw researchers collecting menstrual cycle data of women between October 2020 and September 2021 via a fertility-awareness app.
The participants were between 18 and 45 with at least three cycles post-pregnancy or post-use of hormonal contraception.
Experts say this change is not clinically significant nor a cause for worry.
Speaking with CNN, the lead researcher and professor of obstetrics and gynaecology, Dr. Alison Edelman said the results are reassuring for reproductive health.
The reseacher added that there is more of a personal relationship with the menstrual cycle than clinical, adding that the study will further help people to understand what to expect when they get vaccinated.