Getting a COVID-19 vaccine has been linked to a change in the menstrual cycle among women, per a new study. Dr. Alison Edelman of the Oregon Health & Science University and other researchers studied cycles among 2,403 vaccinated and 1,556 unvaccinated women and concluded vaccination was associated with a change in cycle length. The change was pegged at under one day; no change in menses length was detected. Researchers said that vaccines that use messenger RNA technology—both Pfizer’s and Moderna’s do—trigger an immune response, which could temporarily affect the hypothalamic-pituitary-ovarian axis function, and the study results support the hypothesis. “Our findings are reassuring; we find no population-level clinically meaningful change in menstrual cycle length associated with COVID19 vaccination. Our findings support and help explain the self-reports of changes in cycle length. Individuals receiving two COVID-19 vaccine doses in a single cycle do appear to experience a longer but temporary cycle length …