What is menarche ?

Explanation

### Step-by-Step Solution:

1. **Definition of Menarche**: Menarche is defined as the first occurrence of menstruation in a female's life. It marks the beginning of a woman's reproductive capability.

2. **Age of Onset**: Menarche typically occurs between the ages of 13 to 15, coinciding with the onset of puberty.

3. **Hormonal Changes**: During puberty, significant hormonal changes occur in the female body. The two primary hormones involved are estrogen and progesterone. These hormones are crucial for regulating the menstrual cycle and ovulation.

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