AYESHA RASCOE, HOST:
Girls in the U.S. are getting their first period earlier on average than they did in the 1950s and '60s. That's according to a large new study published this past week in the journal JAMA Network Open. That's a journal of the American Medical Association. And it's taking longer for menstrual cycles to become regular. Here to tell us more about what it all means is NPR health correspondent, Maria Godoy. Thanks so much for being with us today.
MARIA GODOY, BYLINE: Oh, it's my pleasure.
RASCOE: When we talk about early menstruation, how much earlier are we talking about?
GODOY: On average, it's about six months earlier. So the average age used to be 12 1/2 years old, and now it's just under 12. And that may not sound like very much, but the number of girls getting their periods early or very early - so I'm talking about girls under 11 or even under age 9, that's roughly doubled. And while this trend is happening across demographic groups, it's more pronounced in girls of color and those from lower incomes. I spoke with Dr. Shruthi Mahalingaiah of Harvard. She's the study's co- author. And she notes that these trends have big mental and emotional health implications.
SHRUTHI MAHALINGAIAH: You know, the younger you are when you get your first period - it's very confusing. There's still a lot of stigma and silence around it. It's important to educate caregivers, parents, and care providers on this trend so that we can also prepare our children.
GODOY: And, you know, just as importantly, earlier menstruation also has long-term implications for physical health.
RASCOE: So what kind of long-term health issues might these girls face?
GODOY: Well, getting your first period at an earlier age has been linked to health problems like a higher risk of cardiovascular disease, diabetes, and even early death. It's also linked to a higher risk of several cancers, especially breast cancer. Here's Lauren Houghton. She's an epidemiologist at Columbia University whose research focuses on women's health.
LAUREN HOUGHTON: If someone reaches their first period before the age of 12, they're at a 20% increased risk for breast cancer.
GODOY: And this trend toward early puberty and menstruation has been going on for decades, and it's happening around the world. And given that these changes in the timing of menstruation can affect health outcomes later in life, researchers say it's important to be aware of them. Houghton says, we should think of menstruation as a vital sign for health.
RASCOE: So, do we know why this is happening?
GODOY: Well, all the researchers I spoke with say it's not just one thing. It's multiple factors. So, for example, obesity is known to be a risk factor for earlier menstruation in and of itself, but stress is also a known risk factor. And Houghton says, When you're stressed, your body produces more cortisol and more androgens, and these are hormones that fat tissues can then convert into estrogen.
HOUGHTON: And it's estrogen which signals the body to grow breasts, and then it's cyclical estrogen - so changes in estrogen - that signals the body to actually start their menstrual cycles.
GODOY: There's actually another really important factor here. Our environment is swimming in chemicals known to disrupt our endocrine system. For example, things like phthalates, which are found in plastics and in a ton of personal care products and cosmetics, and some air pollutants are endocrine disruptors, too.
RASCOE: Oh, wow. I mean, so what can a parent do?
GODOY: I have a young daughter, and this is top of my mind. One thing is that the advice for healthy living in general, can help with earlier puberty too. So eating a healthy diet with plenty of fruit and vegetables and getting daily exercise can help mitigate some of those risk factors for earlier puberty and menstruation, and can also help reduce the risk of the associated health outcomes down the road if your child does get their period early. Getting enough sleep is tough, but it's also really important. Some studies have linked later bedtimes and shorter sleep duration to early puberty. And of course, if you're the parent of a child who is approaching puberty, talk to them about what they can expect and realize that their first period might happen earlier than you might have thought.
RASCOE: That's NPR health correspondent, Maria Godoy. Thank you so much for speaking with us today.
GODOY: Thank you. Transcript provided by NPR, Copyright NPR.
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