Puberty is like nature’s most awkward surprise party. You don’t pick the date, you don’t get a say in the guest list, but suddenly, your body is like, “Congrats, you’re growing up.” And one of the biggest giveaways? Hair. The kind you didn’t have before—under your arms, along your legs, around your pubic area. If you’ve ever wondered why body hair growth in puberty feels like such a turning point, it’s because it’s literally your body’s way of dropping hints. For girls, the hint is your first period is coming.
Let’s get into the science, the signals, and the real talk about what’s normal, As well as what it all means for your puberty timeline and development.
The Science: Why Does Puberty Change Your Body?
Puberty starts because your brain finally flips the “grow” switch. The hypothalamus (the part of your brain that acts like a control centre for many body processes) sends signals to the pituitary gland (the ‘master’ gland that produces and releases hormones into the bloodstream), which then releases hormones like FSH (follicle-stimulating hormone) and LH (luteinizing hormone). These, in turn, tell your ovaries: time to wake up! The ovaries start producing estrogen, and from there, your body begins a whole cascade of physical changes in puberty.
Estrogen makes your breasts start to grow, triggers fat to be stored differently (hips, thighs, butt), and begins preparing your uterus for menstruation. It also does one more thing, it awakens your hair follicles in new places. According to research, for some girls (about 15%), pubic hair may be the first sign of puberty, showing up before breast budding starts. So if you’ve noticed darker or thicker hair where there wasn’t any before, it’s not random, it’s your body signalling that you’re on the path toward your period.
To get a deeper understand of why any of this is happening, and how this prepares you for adulthood, check this out.
What Body Hair Growth in Puberty Is Telling You
Think of hair growth like the trailer before a movie. You don’t know the exact release date, but the previews mean the premiere is coming soon. Hair doesn’t cause your period, but it’s one of the most reliable signs that your body is gearing up.
Here’s the general order of things when puberty begins (though everyone’s body is unique):
- Breast budding – often the first sign of puberty.
- Pubic hair growth – the first hair stage, starting as light fuzz.
- Puberty growth spurts – sudden height and body changes.
- Underarm hair + oilier skin – hello deodorant and skincare.
- First period (menarche) – usually around 2–3 years after breast budding starts.
Notice how body hair growth in puberty shows up right after breast development and before your period? That’s your body’s calendar.
According to the Mayo Clinic, the puberty growth spurt of hair usually happens about 1–2 years before your first period. So, if you’re in the mirror like, “Wait, where did this come from?”, that’s actually your body giving you a timeline. Hair growth is one of the clearest signs that menarche (a.k.a. your first period) isn’t far away. It doesn’t give you an exact countdown, but it places you firmly in the middle of normal puberty changes.
For more on how your body fully prepares for menarche, read this.
Types of Hair Growth in Puberty: Where It Shows Up and Why It Matters
Let’s break down the different types of hair growth that appear during puberty, why they show up, and what its means for your body:
- Pubic Hair: This is often the first hair change. Estrogen and androgens (steroid hormones, including testosterone, that are the primary male sex hormones but are present in both sexes and affect various tissues like bone, muscle, skin, and the brain) stimulate follicles around the pubic area.
Its purpose in puberty is to signal that the reproductive system is maturing. In adulthood, pubic hair helps reduce friction during sex and provides a barrier against bacteria.
- Underarm Hair: Usually arrives after pubic hair, around the time sweat glands become more active.
Underarm hair’s function is partly protective, it helps wick sweat and reduce chafing. In adulthood, it also plays a role in pheromone release, linking to scent and attraction.
- Leg Hair: While leg hair exists in childhood, puberty hormones make it darker and thicker.
Its purpose is less reproductive and more evolutionary, providing protection and warmth. In modern life, it’s mainly a visible marker of puberty.
- Arm Hair and Fine Body Hair: Across the arms, stomach, and sometimes back, light hair may thicken or darken. These shifts are subtle but mark how hormones affect the entire body. In adulthood, these hairs help with temperature regulation.
Each type of hair shows up on its own schedule in your puberty timeline and development, but together they map the body’s hormonal transformation. They aren’t just cosmetic, they’re functional signals of how your body prepares for adult life and reproductive health.
Normal Puberty Changes: What’s Actually “Normal”?
One thing to remember, normal in puberty is a spectrum. Some people get body hair early, some later. Some people’s first period comes at 10, others at 15. It’s all still considered within the range of normal puberty changes.
Hair patterns vary, too. Maybe your pubic hair is super sparse for a while. Maybe your underarm hair takes longer to come in. Genetics play a role. If your mom or siblings developed later, you might too. If your family has thicker or darker hair naturally, you’ll probably notice that reflected in your physical changes in puberty.
The Emotional Side: Why Hair Feels Like a Big Deal
Hair growth can feel…awkward. Especially when it shows up before you feel ready, or when you’re comparing yourself to friends who don’t have it yet. It’s easy to think, “Why is my body doing this?” But the truth is, hair is a visible reminder that your body is maturing.
Around the same time you’re noticing hair, your body is also likely in the middle of a puberty growth spurt. This is when you suddenly grow taller, your hips widen, and your body starts shifting shape. Hormones are multitasking, telling your bones to stretch, your skin to adjust, and your hair to grow. This combo can feel overwhelming. One day you’re in your favourite jeans, the next day they’re too short. Add in hair popping up in new places, and it’s like your body has a group chat you’re not invited to. But knowing that hair growth is linked to your growth spurt and eventual period can make it feel less random, more connected.
And yes, it also means new routines, maybe shaving or waxing, maybe not, maybe just figuring out how you feel about it. But more importantly, it means your hormones are doing their job and your body is healthy and doing what it’s designed to do.
Owning the Change
Here’s the part nobody says enough, you don’t have to love every physical change in puberty, but you can respect what it means. When hair shows up, it’s an invitation to get curious instead of embarrassed. Ask: Where am I in my puberty timeline? What’s coming next? Understanding the process makes the experience less scary, and more like you’re in partnership with your body instead of fighting against it.
And while it might feel awkward, confusing, or even unfair, it’s also deeply normal—and deeply human.
So next time you notice new hair, instead of thinking “ugh,” think: “Okay, my body is doing its thing. My period is on the way.” That shift in perspective is powerful, and it makes navigating these normal puberty changes a little less overwhelming, and a lot more empowering.
If you’d like to stay prepared once your period arrives, check out Nua’s Teen Comfort Pack, it’s designed with essentials that make managing your first cycles more comfortable and less stressful.
