A retrospective case-control study on menstrual cycle changes following COVID-19 vaccination and disease.

In a previous UK study, participants with polycystic ovary syndrome (PCOS) and endometriosis were “somewhat” more likely to report, respectively, a later and earlier timing of cycle after vaccination (borderline significance), but participants with a pre-existing diagnosis of fibroids and heavy menstrual bleeding were not more likely to report a change in flow as compared to others. 36 Conversely, in the US study, 35 participants diagnosed with fibroids were slightly more likely to experience heavier bleeding.

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