Yet another reason why parents and caregivers should talk to their children about puberty earlier than once thought: their children are starting puberty at earlier and earlier ages. Last month, the Journal of the American Medical Association (JAMA) published a Harvard University study that found that among 71,000 females born between 1950 and 2005, the average age of first period decreased from 12.5 to 11.9 years. Given that it takes about 1-3 years for a girl to start her period once she begins puberty, it then makes sense that girls are starting puberty earlier and earlier. This trend has been observed by doctors and parents over the past several decades. Put differently, the age of puberty in girls has decreased by around 3 months per decade since the 1970s.
What about boys? A similar downward trend is apparent, but it’s not as pronounced and less well studied. The key point to note is that, on average, both boys and girls are entering puberty earlier and earlier, which may have detrimental emotional, social, and even long-term physical/health effects.
Why are our kids entering puberty earlier and earlier? Doctors have a few definitive answers, some hypotheses that need more research, and, unfortunately, a lot of uncertainty. Meanwhile, parents want to know what they can do to support their sons and daughters who are hitting this crucial developmental stage much earlier than when they themselves went through it. They also want to know if there’s anything they can do to appropriately delay the onset of puberty in their sons and daughters.
Quick note: most of the research on “precocious puberty” and the earlier puberty entry points involve girls. This may have to do with the relative ease with which parents, researchers, and girls themselves are able to determine/observe the early physical changes that accompany puberty compared to boys (more on that below). Yet, there are still important implications for both boys and girls (and the parents who care for them), who are all having to deal with the reality of beginning such an important development stage at younger and younger ages.
What is Puberty?
In short, puberty is the developmental stage that nearly all human beings move through that physically, emotionally, and socially transforms an individual from child to young adult. The physical, social/emotional, and behavioral changes are driven by a variety of glands throughout the body that release hormones, each of which have different roles and influences on an individual’s growth. These developmental changes are also impacted by events and experiences outside of our bodies, things related to our family, social circle, popular culture, and life experiences.
Biologically, this array of hormones leads to reproductive maturity for both males and females. And while many of the changes that bodies, emotions, and behaviors go through during puberty don’t directly have a connection to reproduction, others do (think testosterone and its effect on sperm production or estrogen/progesterone on egg maturation and release from the ovary). In fact, it is said that the primary purpose of puberty is to allow for reproductive maturity in individuals so that they may keep the species moving along. Think about it: if none of us went through puberty, the species would have lasted a single generation and then died off.
The Average Age of Puberty
There are records as far back as the mid-1800s related to girls getting their first periods. Back then, the average age was about 16.5 years. Now, it’s 11.9 years (a difference of 4.6 years in about 175 years). Translated differently, the average timeframe for a girl getting her first period is 6th grade. This same girl is likely to begin puberty in 4th or 5th grade.
For boys, it can be more difficult to determine. Since the first signs of puberty in females are mood swings (due to hormonal shifts) and the development of breast buds, it’s a more observable physical change compared to the first physical sign of puberty in males: testicular development. Quite simply, breast buds are easier for parents, doctors, and the child herself to see than changes in testicular size. Thus, it’s been harder over the years to get a clearer sense of exactly when puberty may begin for a particular boy compared to a particular girl.
What we do know is that the average age of onset of puberty for both males and females has trended downward over the decades, with obvious variations from individual to individual. The latest data show the following averages for puberty onset:
- For boys, between 9 and 14 years (roughly between 5th and 8th grades)
- For girls, between 8 and 13 years (roughly between 4th and 7th grades)
Compare these data to previous generations (as Cara Natterson and Vanessa Kroll-Bennett did in their book This Is So Awkward: Modern Puberty Explained), and you see that the average boy or girl in 2024 starts puberty about two years earlier than a generation ago. These numbers provide ongoing support for the fact that, as the decades move along, kids start puberty at younger and younger ages. This begs the question: why is this happening?
Precocious Puberty vs. Typical Puberty
Precocious puberty is a medical diagnosis for an individual child’s puberty that begins much earlier than expected. Given that the average age of onset of puberty has drifted downward, so too has the threshold for precocious puberty. So, for biological females, whose average age of pubertal onset is from 8-13 years, precocious puberty would be considered if she showed signs of puberty at or below age seven. For boys, whose average age of pubertal onset is from 9-14 years, precocious puberty would be diagnosed if he demonstrated signs of puberty at or before age eight. The diagnosis would be given by a pediatrician or pediatric endocrinologist.
Of course, as a parent, if you observe early signs of physical development in your child (as well as sudden moodiness that often accompanies the onset of puberty), you should contact your child’s pediatrician for a consultation.
Physical Changes for Boys During Puberty
Biological boys first show signs of entering puberty by exhibiting mood swings and testicular and penis growth. As the testicles start to produce more growth hormone (testosterone), boys will naturally start to sprout up and experience a growth spurt. Oftentimes, boys will first notice their feet getting larger at a quicker pace. Their extremities (feet/legs, hand/arms) tend to grow first, with their core following behind. Growing pains might occur, but this varies from child to child. With their gain in height, an accompanying and expected weight gain occurs.
As the limbs stretch and shoulders broaden, boys’ muscles will naturally lengthen and allow for more natural strength, which can be exciting for some. Interestingly, boys can develop breast tissue or buds but not nearly as much as their female counterparts. It’s not unusual, however, for many boys to develop some breast tissue initially and then have it dissipate as they move through puberty.
Hair growth usually coincides with these changes (but not always….hair growth actually occurs on a different timeline and because of a different gland not necessarily connected to puberty), with boys seeing hair emerge on their faces (upper lip first), chest (this usually comes a little later), armpits, and pubic area. Boys’ arms and legs also get hairier during puberty.
As the voice box (larynx) stretches out, the voice deepens and usually cracks on its gradual descent to these lower levels. Oil and sweat glands kick into high gear, resulting in oilier skin and the emergence of pimples on the face, upper chest, and upper back. The sweat that the sweat glands produce is a newer sort (given the hormonal shifts in the bloodstream), and so the sweat that’s produced (and that the bacteria on the skin consumes) makes a different kind of smell. That’s body odor. Due to their overactive bodies, some boys will sweat more, including their feet (yes, we have sweat glands on the soles of our feet). As a result, their feet may become stinkier.
Regarding the penis, besides its natural growth, erections will happen with more regularity and spontaneity. With the production of sperm cells by the testicles, wet dreams will happen for a majority of pubescent boys at least once (but it’s not unusual for a boy to never have one).
Why Might Puberty Be Starting Earlier?
As much as we would like to offer clear causes, the unsatisfying answer is that we just don’t know. We do, however, have leads, some of which are better than others::
1. Diet/Obesity/Body Mass Index (BMI):
The Harvard study previously mentioned was able to determine that BMI at the time of first period accounted for a little less than half (46%) of the downward trend in age of puberty onset. This makes sense given the obesity epidemic (especially in the United States) and the fact that, for periods to begin, there needs to be a baseline amount of body fat. So, as childhood obesity has increased, kids may reach this body fat threshold at younger ages. Of course, the availability and popularity of processed foods, which contain high levels of saturated fats, have had much to contribute to the higher BMIs in children. The abundance of foods high in sugar don’t help either.
A 2018 study in the International Journal of Endocrinology looked at three different types of diets in male and female children: “traditional”, “unhealthy”, and “protein”. Unsurprisingly, the only dietary pattern associated with precocious (significantly early) puberty was the unhealthy one. Again, it seems as though diets high in fat and/or sugar have a connection to earlier onset puberty, although not all children with high BMI necessarily start puberty early, and some children with low BMI start puberty early. Clearly, there’s more investigating to be done.
2. Chemicals/”Endocrine Disruptors”:
Other experts are studying the effects of chemicals (also known as “endocrine disruptors”) in the environment that may mimic, block, or interfere with the body’s hormones. Examples include phthalates (found in microplastics among other things), preservatives (found in foods, cosmetics, and pharmaceuticals), bisphenol (a chemical compound that the FDA banned over a decade ago for use in baby bottles and sippy cups), and even air pollution. Trying to research just how these chemicals may affect how hormones act vis-a-vis puberty is tricky, and, so far, studies have not been able to make a link. While it may seem logical that the omni-present nature of these chemicals and pollutants over the past several decades has a connection to earlier age of pubertal onset, the science doesn’t support it…yet.
3. Stress/lifestyle:
Researchers have studied the potential link between stress/trauma to early puberty, but that too can be a difficult line to draw. For instance, there have been attempts to make a causal connection between sexual abuse and early onset puberty (the idea being that higher cortisol levels, due to severe stressors, might result in activation of the pituitary gland). Unfortunately, it is hard to know whether genuine trauma leads to early puberty or early puberty then leads to higher risk of sexual abuse in females.
Other kinds of stress like adverse childhood experiences, crime, and/or poverty may prove to be contributing factors but require more study. Also, many studies have found that Black and Latina girls, on average, enter puberty earlier than White and Asian girls. This may have a connection to psychosocial, economic, and racial/ethnic stressors and experiences. Lastly, a new study has linked parental prenatal stress to earlier pubertal timing in both boys and girls. In other words, those expectant mothers who experienced a high amount of stress during their pregnancies were more likely to have children who entered puberty earlier (up to 2 months) than those expectant mothers who didn’t experience such stress.
Interestingly, data from doctors around the world coming out of the early part of the COVID-19 pandemic indicated an unexpected spike in early puberty cases in females. And while it might be convenient (and even correct) to link this to the stress and anxiety associated with the pandemic, other factors may be at play, including having a more sedentary lifestyle during lockdowns, increased calorie intake, and perhaps even caregivers being around their children more frequently, resulting in them noticing early physical changes in their kids that they might not otherwise have noticed.
4. Genetics:
There are many ongoing studies looking at specific inherited genes to early pubertal onset. And while there have been strides made (we now know that there are hundreds of genes associated with pubertal timing), it is still difficult to know and then reliably predict which inherited genes in which kids will result in an early puberty.
In summary, it seems to be a combination of factors that may lead to early onset puberty. The difficulty is knowing what factors impact which children given their genetics and other environmental variables. The BMI connection seems to be the strongest link to date, but the research will need to bear this out.
What Can Parents Do?
With all of this research trying to pinpoint the causes of early puberty, parents can be left feeling confused about what, if anything, they can do proactively to either stave off early puberty for their child or appropriately respond when they notice or suspect that their child may have begun puberty earlier than expected. Given the multiple factors that appear to play into early puberty, there are some proactive and responsive actions that parents can take.
Things parents can do proactively:
- Limit the saturated fats in your child’s diet. Diets that are high in fat can lead to increased body fat, which is associated with earlier onset puberty.
- Limit foods and drinks high in sugars (especially soda). The usual suspects are: candy, soda, the range of sweets and desserts. Again, high sugar foods and drinks will lead to higher body fat, which is correlated to earlier onset puberty.
- Promote a healthy diet and nutrition by providing balanced meals with plenty of fruits, vegetables, proteins, nuts and grains, and less processed and fried foods. This is a no brainer.
- Make sure your child moves his or her body. Sedentary lifestyles will lead to higher body fat. Active lifestyles generally won’t.
- Do all you can to limit or buffer excessive levels of stress in your child’s life. This doesn’t mean that you should become a “snowplow” parent and prevent your child from experiencing and then learning how to manage typical, everyday stress. It means that you should do all you can to provide a safe, secure, and fairly predictable environment in which your child can grow and develop. Stressors that might be considered more extreme include moderate to severe marital conflict, parental drug or alcohol abuse, excessive bullying, or physical or sexual abuse. Moderate levels of stress might include premature use of social media (which we know is strongly correlated with anxiety and depression in large percentages of children and teens). Think of stress as either a healthy, necessary emotion/experience that builds resilience and confidence or an unhealthy, unnecessary one that overwhelms children and shuts them down. Do all you can to reasonably reduce or eliminate the unnecessary kind of stress for your child.
- Start talking to your child early and often (more than you originally thought) about how their bodies are going to change. There are so many resources (books, websites, videos) out there to assist parents in finding the words and ways to start these conversations (see my blog entitled, “Breaking The Ice and Taking The Plunge: Tackling The Sex Conversation at Home with Your Son” for a list of some). Lots of bite sized conversations are more easily digestible for younger kids than just a few, longer ones. This means that by age seven, both boys and girls should start learning about their bodies and how they will be changing. This is especially true for girls given that their bodies change earlier than boys. However, it’s just as important to talk with boys about their own inevitable body changes, as well as the changes that will happen for the girls in their orbit. This will equip boys to be knowledgeable, understanding, sensitive, and supportive of their female counterparts who are undergoing noticeable changes to their bodies.
Things parents can do if they notice their child is showing signs of early puberty:
- First, take a breath. Then message your child’s pediatrician and set up a time to consult with him or her. This might be a phone call but will likely be an office visit with your child so the doctor can examine your child. Depending on your child’s age, a referral to a pediatric endocrinologist may be appropriate to discuss further options.
- Whether or not your child has been diagnosed as having precocious puberty, talk to him or her! If you’ve already had earlier talks about changing bodies, great. Now it’s time to discuss that the changes are actually starting to happen and how to start taking care of his or her developing body in new and important ways. Check in fairly regularly to see how they’re feeling about these changes and make sure they understand that you’re there for them as a constant, consistent, and trustworthy support. If you haven’t had earlier talks about changing bodies, obviously you’ll need to start right away given that these changes are underway.
- Make sure you let your child know that you will have regular check-ins with him or her about these changes. Part of these check-ins should include talks about how they’re feeling about the physical and social/emotional changes. How are others (acquaintances, friends and family) responding to these changes? What does that feel like for your child? How can he or she manage these feelings when others aren’t responding in ways that feel good? By the way, this is especially important because “early bloomers”, especially girls, are more likely to be teased, bullied, and sexualized. They might feel very out-of-sync with their peer groups, which can lead to mental health struggles.
Remember, these are children whose chronological age and developmental age are misaligned. As a parent, don’t forget this point and remember to treat your child the age that he or she is, not like the age he or she appears. Partner with the school psychologist and/or teachers to get a real sense of how your child is interacting with others on campus, and how others are responding to him or her.
Despite the potential physical, social, and emotional fallout that can occur from early puberty, parents and caring adults can help children develop the skill sets they need to navigate these choppy waters. Empowering children with knowledge about bodies and how they change and grow ahead of time is always a good place to start, with continued healthy conversations as those changes emerge.