Periods are these annoying visits from Mother Nature that happen to girls every 28 days or so. They allow women to become preggers and have duh baby, but at a cost, primarily blood. The ironic thing is that the blood loss creates an iron deficiency, which allows women to live longer then men because iron makes your cells age, so the less iron you have, the longer you live. Now ya know. Normally, a girl gets her 1st period in between 11 and 14. Anywhere in between 11 and 14. The crying rate in girls during that time can increase up to 5x. When girls have period, they will mostly have a stomachache, but sometimes there's an exception because not all girls have period pain.