Periods.

(to male readers.. sorry, I guess. Nope. I'm not sorry.)
Girls have to handle periods. Fact of life. Sorry.
But how does one avoid it? I have the answers right here.

a) get pregnant then handle 18 years of a pain in the arse as well as your periods.
b) get so unhealthy that it is physically impossible to have a period.
c) wait for menopause... that's.... in your 50s. If you're lucky.
d) die.

This has been a comprehensive list of methods to avoid your period.
I wish you luck in your future endeavours.