What Does It Mean to Be a “Late Bloomer”?

If puberty was a yardstick, then late bloomers would sit at the far right, somewhere near the three foot mark. If puberty was a football field, late bloomers would be clustered into one endzone. If puberty was a marathon, late bloomers would find themselves hanging out near mile 26. 

“Late bloomers” are the ones who go last – the ones whose curves or muscles or growth spurts happen well after everyone else has been there, done that. Or at least, this is how it feels. The actual definition of late blooming in puberty is a function of what is happening inside the body, even though the way we tend to describe puberty has everything to do with what others can see on the outside.

The average age of puberty onset in the US is around 8-9 years for genetic females and 9-10 years for genetic males.(Twenty20 @simonenicolephotography)

Who is a late bloomer?

Let’s start by defining the terms. The average age of puberty onset in the US is around 8-9 years for genetic females and 9-10 years for genetic males. Yes, it’s earlier than it used to be! (If you want more on this topic, read our article on early bloomers.) But the age of late onset puberty hasn’t really changed that much over the generations.

Females are considered late if they don’t have any external secondary sex characteristics – like breast development or hip widening – by about 14 and if they haven’t gotten a first period by 16. Males are late if they have no measurable testicular growth by the time they turn 14. Important note here: most guys aren’t measuring their testicles; they’re looking for evidence of puberty via other features like increased lean muscle mass, a growth spurt, and a cracking or deepening voice. 

How does puberty begin?

What kicks off puberty? It’s all about hormones. A gland in the brain called the pituitary gland tells the ovaries in females or the testicles in males to begin producing estrogen and testosterone respectively. This internal messaging flips on a cycle of feedback loops, where hormones rise and fall, turning on and off other hormonal pathways.

It’s an incredibly elegant system, but one that relies upon peaks and troughs – which can help to explain the moodiness of this stage of life. (Learn more about the impact of hormones on tweens and teens.)

Once puberty has begun, how long until it’s noticeable?

How long does it take to see that puberty has started? That varies quite a bit! It can take a year or two before the hormones circulating in some bodies result in noticeable external shifts. The very earliest moments of puberty are easier to see in males, because their testosterone-making machines – the testicles – are more visible than the female ovaries that make estrogen.

But these early shifts are often only noticed by pediatricians who examine kids’ bodies and note gradual testicular growth. It can take a long time before parents or friends see bulging muscles or hear a deepening voice. 

Does starting late matter?

Does it matter if someone is late? In most cases, it doesn’t make a huge difference biologically but socially, late puberty can feel like a really big deal to kids. Take a typical genetic male: if the average age of starting puberty (aka testosterone production) is just before or around the 10th birthday but it’s considered “normal” to not start until age 14, then there is a group of boys who wait up to four years to catch up with their developing classmates.

And while those 10-year-olds who start “on time” may not look very manly yet, the 14-year-olds who are just getting started often appear much younger and shorter than their peers. Because genetic females tend to enter puberty slightly earlier than genetic males, the late blooming boys are often the last of the last to physically mature. So late blooming can be a case of nothing’s-wrong-but-everything-feels-wrong. 

When to see a doctor

When should you see a doctor? While most bodies get there when they are ready, there are medical issues that delay puberty – uncommon, but not non-existent. Anytime there’s a physical or emotional worry, it’s a good idea to check in with your healthcare provider. If the visit results in a little reassurance, that’s great! And if there’s something else going on that your doctor wants to follow more closely, then good thing you checked.

Parents and trusted adults may be tempted to examine kids themselves in order to help reassure the kids (and themselves) that everything is fine, but this is generally not a great idea. Many tweens and teens are highly private – the last thing they want is for an adult to do a physical exam looking for sexual maturity…even if that adult works in healthcare!

So yet another reason to check in with your health care provider if you are concerned. This is much more effective and far less anxiety-provoking, by the way, than checking Google. 

Long term impact of being a late bloomer

Are there long term impacts of being late to the puberty party? Maybe. For most kids, late blooming is really being on the later end of normal. Again, none of us should minimize how this feels socially or psychologically. But for the few who qualify as truly late, which amounts to about 2.5% of all kids, the long term consequences vary by gender.

A genetic female who enters puberty late will often (though not always) enter her growth spurt late, eventually winding up taller than many of her peers. However, the height math does not necessarily work the same in genetic males.

In fact, for late blooming guys, their growth actually tends to slow at the very time that their friends are heading into puberty – making size differences all the more noticeable during middle school –  and when they do go through their pubertal development, many of them have shorter (timewise) growth spurts, resulting in less height gain than many of their peers. 

What you can do

The Takeaway: Puberty is a tricky time – awkward at points for almost everyone who is in it. And, as it turns out, for those who aren’t in it as well. Being late to physical development can be as tricky as being early (or, as many teens will say, as tricky as being on time, too!)

The most important thing you can do is to listen to a kid who wants to talk about it. If you don’t have answers, get them from a health professional, not the internet. And if they’re feeling particularly alone in this situation, you might want to point to some pretty amazing late bloomers who are unafraid to tell their stories. 

This article was co-authored by Dr. Cara Natterson and Vanessa Kroll Bennett, co-hosts of The Puberty Podcast. For a deep-dive on the topic of late bloomers, you can listen to this episode on the science of late bloomers.

More Great Reading:

Four Ways to Navigate Tween and Teen Mood Swings and Emotions

About Cara Natterson

Cara Natterson, MD, is a pediatrician, New York Times–bestselling author, and co-founder and CEO of OOMLA, a company designed to make puberty more comfortable (literally) by creating content and products for tweens and teens. She co-hosts The PUBERTY PODCAST which updates adults on how this transformative stage has changed (and oh, has it changed!) and recently launched the TikTok channel SpillingThePuberTea. Cara’s puberty books – including The Care and Keeping of You series, Guy Stuff and Guy Stuff Feelings – plus her parenting books – most recently Decoding Boys – are read by millions. She graduated from Harvard College and Johns Hopkins School of Medicine; she trained in pediatrics at the University of California at San Francisco; and she is a board-certified pediatrician and a fellow of the American Academy of Pediatrics. But Cara learned most of what she knows from the two teenagers living under her roof.

Read more posts by Cara

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