Some women have reported changes to their menstrual cycle – including early or late periods – after taking a COVID-19 vaccine

In addition to delayed or early starts, some women have reported symptoms including spotting, severe cramping, heavier than usual flows and “prolonged menstruation,” the doctor added.

https://english.alarabiya.net/features/2021/09/14/COVID-19-vaccines-may-cause-temporary-disruption-to-women-s-periods-expert-weighs-in