What event officially starts the entire menstrual cycle?

Answer

The first day of menstrual bleeding

The menstrual cycle is defined as beginning on the very first day that menstrual bleeding starts, marking the initial phase known as menstruation. This day sets the stage for the entire sequence of hormonal events that follow throughout the cycle. The cycle officially concludes the day just prior to the start of the subsequent period. This definition helps establish a consistent starting point for tracking the biological process, despite the entire process spanning several weeks and involving complex hormonal interplay preparing the body for potential pregnancy.

What event officially starts the entire menstrual cycle?
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