When you were a teenager, getting your first period was everything. You were excited about the idea of "becoming a woman" and also completely freaked out about the idea of bleeding out of your vagina.
Now that you're a seasoned period pro, it's easy to forget how much you obsessed about your cycle back then. But it turns out, all that attention was worth something, since the age when you first got your period can actually impact your future health.
First, let's back up a little: There's a medical term for the age when you got your first period—menarche. Girls have started getting their first period earlier than in the past, so now it's considered "normal" for girls to get their period between 9 and 14 years old, says Maureen Whelihan, M.D., an ob/gyn at the Center for Sexual Health & Education. However, Jessica Shepherd, M.D., an assistant professor of clinical obstetrics and gynecology and director of minimally invasive gynecologic surgery at the University of Illinois College of Medicine at Chicago, says doctors aren't really concerned if you get your period later, unless you get to age 16 sans period—at that point, they'll want to girls to get examined just to make sure everything is working OK in there.
Your menarche is influenced by a few things, but it's largely due to genetics (that explains why you might get your first period around the same age as your mom or sister...) However, environmental factors and even your weight can play a role, says Whelihan. Having the right amount of body fat is critical to producing the hormones that lead to your first cycle, which is why girls tend to put on a little weight before they have their menarche, she says.
A higher-than-average weight can also cause girls to get their period earlier than usual, says Shepherd. "We think the increase in obesity in society may be one of the reasons why girls are getting their first periods earlier," she says.
But back to the whole "influencing your future health" thing.... There are pros and cons, no matter when you got your period.
Girls who get their periods on the earlier side are at a slightly higher risk for breast cancer, according to the Susan G. Komen foundation, which specifically calls out data that says girls who got their periods before age 12 have about a 20 percent higher breast cancer risk compared with those who began their periods after age 14. It has to do with estrogen exposure, Whelihan explains—the longer you're exposed to estrogen in your life, the greater your risk.
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Getting your period on an extreme end—early or late—can also increase your odds of having heart disease later in life, according to a study published last year in the journal Circulation. For the study, researchers followed 1.2 million women who didn't have heart disease, stroke, or cancer, and broke them into groups based on when they got their first period. Girls who had their first period when they were 10 years or younger, or at 17 and older, were 27 percent more likely to be hospitalized or even die from heart disease down the road. They were also 20 percent more likely to be hospitalized or die from high blood pressure complications. "It's all estrogen based," Shepherd says.
Your mind can be affected by your menarche too: Researchers from the University of Southern California also just discovered that getting your first period before age 13 is linked with having better brainpower after menopause.
Getting your period at a later age has been repeatedly linked to a decreased risk of ovarian cancer, Shepherd says. "Every time you ovulate, it can change the ovarian tissue, which can increase your chances that a tumor can occur," she explains. "The later you start your period, the less you ovulate." (This also explains why birth control pills decrease your risk of ovarian cancer, she says.)
While it stands to reason that getting your period later means you'll be fertile for a longer time, Shepherd says that isn't the case. "We're born with millions of eggs—there's no way you can deplete all your eggs," she says.
Of course, whether you got your period at 10 or 17, you shouldn't freak out and assume it means you'll get ovarian cancer or be super forgetful when you hit menopause. There are many other factors that go into these diseases and your overall future health, like eating well, exercising regularly, and avoiding smoking.
Still, super fascinating info!