Researchers from the University of Edinburgh’s Centre for Reproductive Health (UK) have discovered that Long COVID is linked to abnormalities in the menstrual cycle — in particular, unusually heavy bleeding, prolonged menstruation, or intermenstrual spotting, even though ovarian function remains intact.

The results of their study were published in Nature Communications.

The research included several components: an online survey, symptom-tracking data collected via an app, as well as blood tests and endometrial samples from women with Long COVID and from a control group. They compared women who had never had COVID-19, those who had experienced the acute form, and those who developed Long COVID.

The findings showed that women with Long COVID were more likely to experience heavy menstrual bleeding, periods lasting longer than eight days, missed periods, and intermenstrual bleeding. However, menstrual frequency and cycle regularity did not differ significantly.

Menstrual cycle symptoms were most pronounced in the late secretory and menstrual phases, as well as the proliferative phase. In women with Long COVID, blood samples revealed higher levels of 5α-dihydrotestosterone during the secretory phase. Endometrial changes were also observed: fewer androgen receptor–positive cells and increased inflammatory activity.

The authors concluded that while ovarian function is largely preserved in Long COVID, key factors likely include disruptions in androgen regulation and inflammation. They recommend further research into targeted treatments and emphasize the importance of considering menstrual cycle phases when developing biomarkers and therapies.