Is the Age of First Period Getting Younger? What the Research Shows (Episode 529)

Full Transcript: Episode 529

Lisa: Today I’m sharing a brand new episode in my FAM research series. And in today’s episode, we’re covering an interesting question: are teenage girls getting their periods earlier than their mothers did? So we’re going to be diving into a research study that looked at this question.

So I always say that the names of these research studies leave something to be desired, but the name of today’s study is “Study on Age of Menarche Between Generations and the Factors Associated With It.” And what’s interesting about this question is that when you look at the research, generally speaking, the average age of menarche does tend to fall somewhere between about 13 years of age, give or take. But we all know that some girls will start menstruating earlier or later. And in your own life, you may be able to think of some girls who have started menstruating quite a bit earlier or quite a bit later.

So I think the earliest menstruation that I have had a conversation with somebody about — so kind of like that direct exposure — would be about 9, which is super, super early. I’ve also known of girls to menstruate of course around age 10. And if you’ve listened to any of our reality series episodes — whether it be the pill reality series or the FAM series where real women are sharing their experiences of menstruation and pill use and those kinds of things — there have been a number of women on the show who have shared that they’ve had an earlier menstruation at about age 10. And I would say that that situation is associated with certain challenges from an emotional standpoint. In my interviews, I found that women who start menstruating earlier are less likely to have been informed fully about the process of menstruation. So understandably, if a young girl starts menstruating but she really has never heard of it or didn’t really know much about it, it can be extremely traumatic.

And on the flip side, when I’ve interviewed women who started menstruating you know later on — similar to myself — so when I look back, I started menstruating at about 13, closer to 14. I think I started menstruating the month before my 14th birthday. And so by that point, a lot of my friends had already started menstruating. I was old enough. I had learned about it. I knew about it. And I was very much prepared for it. I was actually waiting for it impatiently, and so when it finally happened, it was kind of like: okay, there it is. But that would be a very, very different experience for someone who is a youngster.

Now with that said, in this study they’re not necessarily looking at the kind of emotional impacts — they’re more asking the question about what factors could be having an effect if there is this change in the onset of menstruation. So they’re looking at lifestyle factors: things like sleep, whether it’s exercise, dietary habits, and a variety of other scenarios, and looking at if those things could have an impact on this kind of earlier onset of menstruation.

What’s interesting about this study is that they’re not really looking at some of those more emotional impacts that I was talking about. They’re more looking at whether or not the onset of menstruation has changed and they’re looking at it between generations. So what’s interesting is they actually had 200 participants — 100 adolescent girls and then 100 of their mothers — making 200 participants total. And they asked each group all these different questions to determine if there was an overall difference between mother and daughter in terms of onset of menstruation and other similar factors.

So while I was talking a little bit about how having an early menstruation or a later menstruation could affect you personally, they’re looking at a different question, which is more: what factors could be affecting those shifts? So unsurprisingly, I think, what they did find is that the daughters — the younger generation — did have on average an earlier onset of menstruation. When they compared the average onset of menstruation between the adolescent girls and their mothers, the adolescent girls’ average age of menstruation was at age 12.5 versus the average age of menstruation for their mothers, which was 14 years of age.

And so what they found obviously is that there is this trend toward a decline in the age of the onset of menstruation, or the age of menarche. And what’s interesting is the researchers start the study by talking about this trend that they’ve observed — and it’s not just in one area or the next, or in one country or the next. They list a variety of different countries where they’re seeing this trend across the board. So for example, they’re listing a trend toward earlier menarche in England, Israel, China, India, Korea, Ghana, Mexico, Thailand, the US. So they’re going through all of these different countries where they’ve observed similar trends.

So there is research to suggest that early menarche is associated with certain health issues — whether that be more behavioral type issues related to self-esteem or early sexual activity, or whether it’s related to certain health conditions, for example obesity, diabetes, or cardiovascular disease. And there is some research to suggest that there is a link between the early onset of menstruation and body mass index. Of course, this association is there because there is an association between your body mass index and your period, suggesting that you need to actually reach a certain BMI before your menstruation will start. And this is also discussed in women who lose their period — let’s say if they’re on that hypothalamic amenorrhea spectrum and they’re significantly underweight — often they won’t resume menstruating again until they reach a more ideal weight.

So this study highlighted some interesting stats. When they looked at the 100 responses of the adolescent girls, they found that only 1% reached menarche at 9 years of age — that was the earliest. They found that 7% started menstruating at 10 years old, 16% started menstruating at 11, 29% at age 12, 24% at age 13, 16% at age 14, 6% at age 15, and 2% at age 16. So if we put that all together, it just means that the majority of teenage girls are starting to get their periods around age 12, 13, 14 — but some do get their periods as early as 10 or 11, with 9 being a more rare case. And then there are a small percentage of teenage girls who are then starting their periods after age 14.

Okay, so when they compared this data to the mothers of the group — when they looked at the 100 mothers and compared it to the 100 daughters — the youngest age of menarche among that group was actually 10 years, and only 1% of the mothers had an onset of menstruation at that age. 6% started menstruating at 12 years, 33% at 13, 32% started menstruating at 14, 22% at age 15, 5% at age 16, and 1% at age 17. So if we compare the mothers — we’re seeing a greater percentage of those, when they were younger, starting menstruation at age 12, 13, 14, and even 15, whereas within the younger group, they were starting to menstruate a bit earlier. So I think overall, we still see a similar age group, but we’re definitely seeing that trend toward younger ages at the start of menarche.

So what does this information tell us? When we look at these types of studies, what is the overall and broader implication of this data? What’s interesting is the way the researchers were looking at it: they were looking at the different factors that could be contributing to an earlier menstruation. And one of the things they were suggesting — at least in this study — they found a link between lifestyle and activity and this trend toward an earlier menarche. So they go into this a little bit and they’re suggesting that because our younger generation is more sedentary, because we have less physical activity now — again, this is what the researchers are suggesting — they’re suggesting that overall our young women have less activity, they’re more sedentary than the previous generation. They’re suggesting that they spend more time whether it’s on devices or television or tech and all the things, and they’re suggesting that this has an overall impact on BMI but also they go on to talk about the potential impact of this increased sedentary lifestyle with the way that our bodies process estrogen.

So if I read a little bit from the study, what the researchers said was that “the finding of the study revealed that the average age of menarche in the adolescent girls was decreased compared to the mothers and it was also noted that menstrual cycles are regular in the mother compared to their daughters.” They say: “There was a significant difference in the habitual and lifestyle pattern among mother and adolescent girls. It was found in the study that lifestyle pattern — whether active or sedentary — plays a significant role in the decline of the menarche age.”

So what’s interesting as well is they have a hypothesis as to how this is affecting things. They’re suggesting that because we know that physical activity reduces our endogenous estrogen — the estrogen that we produce in our bodies — they’re saying that when you have an increased level of physical activity, your metabolism is increased, as is your body’s natural ability to break down and clear estrogen from the body. And so they’re suggesting that when we have a higher kind of sedentary lifestyle, we end up clearing less of our estrogen or clearing it less effectively. They’re suggesting that this is especially relevant and critical when we look at teenage girls in particular, because during this time of puberty, we are even more sensitive to the impacts of estrogen. And they’re suggesting that when we have an increased sedentary lifestyle in this phase of life, it could potentially increase the amount of estrogen we actually have on board, because we are then not clearing our estrogen as effectively, not breaking it down, not getting rid of it. And during this time of adolescence, when we’re particularly sensitive to this output of estrogen, it could lead to an earlier onset of menstruation.

Now it’s interesting to think about this because of course there are other theories around it. There are other research papers that particularly look at weight and would suggest that obesity is the result. And there are other papers that would look at nutrition or look at the impact of chemical exposure and how all of those things could be changing when girls are getting their first period.

And within the research, there’s this average age that is normal — and that’s somewhere between 12, 13, 14, potentially 11 on the younger end, and I should include 15 as well. But then when we see the age of menarche on the outer ends — when we’re seeing it at age 9 or age 10, when we’re seeing it at age 16 or age 17 — then there are other factors that could be at play. And I suppose this whole conversation goes back to the concept of the menstrual cycle as a vital sign.

Some of the organizations that are sharing this idea are often focused on adolescents and why we should pay particular attention to the onset of menstruation and how menstruation is taking place in young girls, because it is a sign of health. It’s certainly possible that the early onset of menstruation when it’s happening before age 12 — if it’s happening at age 10 or age 9 especially — could be an indication of things we should be looking at related to BMI and other potential factors, whether it be the sedentary lifestyle that they’re talking about here in this paper or other potential factors like chemical exposure. And then when menarche is delayed — when we’re seeing girls who are 16 or 17 — it should really be a red flag for us to be looking at what could be delaying that from happening.

I do remember a podcast episode where I interviewed a woman who was sharing her experience on the pill and how she had experienced a pulmonary embolism as a side effect. But in that interview, she shared that she had a delayed menarche and had been put on the pill before she ever had her first period. I think if I remember correctly, she hadn’t even had her first period naturally at this stage, because she had been put on the pill proactively. And so I would say that’s not the right decision. I think that when a girl is not having her period after age 16, we should definitely be looking at it. And within that conversation, she shared that she was really paying close attention to her weight, exercising a lot, and restricting her eating — so it’s very likely in her case that that would have been contributing to this delayed onset of menstruation.

So one thing I like to consider toward the end of all of these research series episodes is: what does the study tell us? I think the study provides us with some really interesting information about the trends in the onset of menstruation. For any of you who have daughters, sisters, nieces, goddaughters — all of the girls in your life — it does make you think. And I’m now a mother of a daughter, although she does have quite a ways to go before she reaches menarche. But I’ve certainly thought about this as I’ve watched my boys grow up. My youngest son is eight, about to be nine, and my eldest is 11, about to be 12. And I just look at — especially my younger son at 8 turning 9 — and I think to myself: that would be really challenging for a girl of that age to be going through the same thing. It does feel quite young, and I think all of us kind of intuitively feel that.

One thing to consider is that within this conversation, when we put aside the extremes of way too early and way too late, what we do see is that there are some positive aspects of this trend toward earlier menarche. There is some research to suggest that earlier menarche — of course, within what we would consider to be normal and optimal — is associated with improvements in nutrition and improvements in exercise and overall positive dietary and lifestyle changes. And that’s suggested to be one of the reasons why we’re seeing this downward trend.

So I would say the overall takeaway from this research is that there is a connection, obviously, between our menstrual cycle and our overall health. And as we’re raising our daughters, it’s really important and essential to be optimizing their nutrition to the greatest degree, making sure that they’re consuming nutrient-dense meals, making sure that we’re minimizing their chemical and toxin exposure, and supporting them to have a healthy balance of physical activity and nutrition. And ultimately, that combination, when it’s done in an appropriate way, would lead us to more likely have that menarche be within that sweet spot — between that age 12, 13, 14 — that is kind of that center of what we would consider.

One thing I do want to say, though, is that I know that some of you listening probably did have an earlier menarche or did have a later menarche. And I wouldn’t want you to take from this episode that there was something wrong with you or anything like that. We’re not robots, and there are a lot of different factors — some of which we wouldn’t even necessarily know about — that contribute to when we are going to start our periods. There is some discussion even for menopause — when we have our last period — and how that relates to other women in our family. So it’s certainly possible that there could be other factors. While we’re talking about lifestyle factors and other factors that could be contributing, I don’t think that we know everything there is to know about the onset of menstruation.