Around age 9 to 13, girls enter puberty and have their very first period.
From this day forward, their hormone levels fluctuate, affecting their body, brain and behavior - a phenomenon known as the menstrual cycle.
The menstrual cycle is divided into 4 phases: Menstruation, follicular phase, ovulation with a fertile window, and the luteal phase.
The length of the cycle is, on average, 28 days. However, for most women it ranges somewhere between 22 and 35 days and can be regular or not.
Since menstruation is a consequence of changes that happen before it, we will start our story with the follicular phase.
During the Follicular phase, the hormone estrogen increases steadily and Leah starts to feel happy, is physically stronger, and is generally on top form.
Inside her body, her uterine lining starts to thicken and in the ovaries, her follicles mature. Inside one of them is a tiny cell that's about to become an egg.
At the end of this phase, Leah notices a change in her discharge. During Ovulation the ovary releases the egg, which makes its way towards the uterus and then implants itself inside the lining.
For about 5 days, Leah could potentially get pregnant. The high levels of estrogen make Leah more interested in boys than she used to be, which is why she is more conscious about her appearance.
Her senses are heightened and she hears, sees, tastes and smells more acutely. In the Luteal phase, her body temperature rises slightly.
