COVID-19 linked to small menstrual cycle length changes that resolve quickly

Key takeaways:

• Women with COVID-19 experienced a 1.45-day increase in menstrual cycle, and women with COVID-19 vaccination had a 1.14-day increase.
• These changes resolved within the next cycle.

Having COVID-19 was associated with a small change in menstrual cycle length like that observed with COVID-19 vaccination, with changes resolving within the next cycle, researchers reported in Obstetrics & Gynecology.

Previously, Healio reported on study results published in BJOG that found a small increase in the likelihood of greater total bleeding during menstrual cycles after receiving COVID-19 vaccinations.

“The immune and reproductive systems are known to interact with each other, and temporary disruption of the menstrual cycle is seen with acute infection and febrile episodes,” Alexandra Alvergne, PhD, CNRS research fellow at the Institute for Evolutionary Sciences at Montpellier University, France, and the University of Oxford, U.K., and colleagues wrote. “However, previous literature on the association between COVID-19 and menstrual cycle changes is scarce and inconsistent, limited by small samples, recall bias, lack of comparison groups or small subgroups of participants with COVID-19.”

Alvergne and colleagues conducted a retrospective cohort analysis with data from 6,514 women from 110 countries aged 16 to 45 years who used a period tracker app and who responded to a survey regarding COVID-19 symptoms and vaccination. Researchers analyzed prospectively tracked menstrual cycle length data and calculated the within-user change in cycle length from the three consecutive cycles before vaccination, disease or neither to the event and post-event cycles. All participants had normal cycle length of 24 to 38 days and regular tracking behavior during the five cycles recorded around COVID-19 symptoms, vaccination or a similar time period.

Overall, there were 32,570 menstrual cycles analyzed. Of all participants, 1,450 had COVID-19 symptoms, 4,643 had been vaccinated against COVID-19 and 421 had neither the vaccine nor COVID-19 symptoms.

Women with COVID-19 experienced a 1.45-day increase in menstrual cycle length during their fourth cycle compared with the three pre-event cycles. Women who were vaccinated against COVID-19 experienced a 1.14-day increase in menstrual cycle length during their fourth cycle compared with their pre-event average. Women in the control group experienced a 0.68-day decrease in their menstrual cycle during a similar period as those with COVID-19 symptoms or COVID-19 vaccination.

Researchers observed no significant differences in the extent of changes between women with COVID-19 symptoms or COVID-19 vaccination in post hoc tests. The menstrual cycle length changes resolved within the next cycle post-event for both groups.

“In summary, although the proportion of individuals who experienced a clinically significant change in cycle length of more than 8 days was higher for those with COVID-19, at the population level, experiencing COVID-19 was associated with a small and temporary change in cycle length similar to that with COVID-19 vaccination,” the researchers wrote.