According to a new study, COVID vaccinations may temporarily lengthen a woman’s menstrual cycle. In comparison to uninfected women, women who received one dose of a coronavirus vaccine during their menstrual period observed their cycle lengthen by up to one day as reported by Study Finds.
The National Institutes of Health (NIH)-funded research discovered that changes in cycles alter the time between bleeding but not the duration of bleeding.
Influence on menstrual cycle
Study authors, led by Dr Alison Edelman from the Oregon Health & Science University in Portland, confirmed that it is not uncommon for menstrual cycles to vary from month to month and the increase they found was “well within the range of normal” variability.
Dr Edelman adds that further research is necessary to determine how COVID vaccines could influence other menstrual characteristics like pain, mood changes, and the heaviness of flow.
In a bid to understand why the changes occur, the team analyzed data from the fertility tracking app, Natural Cycles.
To get an accurate reading, users have to input data on their temperature and menstrual cycles.
For vaccinated women, researchers looked at data from three consecutive cycles before the patients received the vaccine and from three more consecutive cycles after — including the cycle or cycles in which their vaccination took place.
2 days longer
Of the 3,959 individuals in the study, 2,403 were vaccinated and 1,556 were unvaccinated. Most of the vaccinated app users received either the Pfizer or Moderna vaccines. On average, the first vaccination dose displayed a connection to a 0.71-day increase in a woman’s cycle length. A second COVID vaccine dose increased cycle length by 0.91 days.
There were no changes in the number of menstrual bleeding days for the vaccinated patients and the researchers did not detect any significant change in the cycle length for unvaccinated app users. However, 358 app users who received two doses of the coronavirus vaccine during the same menstrual cycle experienced a noticeably larger average increase in their cycle length — lasting up to two days longer.
According to the researchers, this change appeared to decrease in the following cycles, which suggests that the menstrual changes are temporary and will go away shortly after vaccination. Dr Bianchi and the team add that the International Federation of Gynecology and Obstetrics classifies a change in cycle length as “normal” if the change is less than eight days.
Did you subscribe to our newsletter?
It’s free! Click here to subscribe!
Source: Study Finds
