"My daughter shot up in height at 11, but my son didn’t seem to grow until high school. Is that normal?"
Many parents notice that girls often grow earlier, while boys seem to grow taller overall. These differences can cause concern, especially when siblings or classmates hit growth spurts at different times. The good news is: this pattern is not only normal, it’s expected. And science explains why.
Understanding how boys and girls grow differently—in timing, speed, and duration—can help parents know when to support their child’s growth and what to expect during puberty.
When Do Growth Spurts Happen?
Puberty doesn’t start at the same age for every child. Girls typically begin puberty between ages 8 and 13, while boys start later, around 10 to 15.
Timing of Peak Height Velocity
Peak height velocity (PHV) refers to the period during puberty when a child experiences the fastest rate of height gain. On average:
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Girls reach PHV around 11.5-12 years, typically about 12 months after breast development begins, during Tanner stage 2–3.
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Boys reach PHV around 13.5-14 years, roughly 18 months after the testes begin to enlarge, during Tanner stage 3–4.
This means girls often grow sooner—but not necessarily more. Girls tend to enter their growth spurt early, while boys reach their peak later but sustain it longer. Studies show that about 69% of girls and 59% of boys reach PHV during these middle Tanner stages, highlighting a consistent sex-based developmental pattern.
Source: Obgyn Key
The Hormonal Orchestra Behind Growth
Hormones are the body’s internal growth messengers. In puberty, the biggest players are:
Estrogen and Testosterone
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Estrogen (primarily in girls): Triggers early puberty signs and speeds up growth initially—but also signals the growth plates in bones to mature and eventually close. Once closed, further height increase is no longer possible.
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Testosterone (primarily in boys): Stimulates muscle and bone lengthening and extends the growth period. Importantly, testosterone partially converts to estrogen in the body to help bones mature, but this conversion occurs more slowly in boys, allowing longer growth before the plates close.
Final height is largely determined not by when puberty starts, but by how long the growth plates remain open—a process driven by hormonal timing.
The Role of IGF-1
Another key hormone is IGF-1 (Insulin-like Growth Factor 1). It's produced in response to growth hormone (GH) and acts directly on bones and tissues to promote growth.
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During puberty, rising sex hormone levels increase GH secretion, which in turn boosts IGF-1.
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Boys’ later puberty means their IGF-1 peak occurs later—and stays elevated for a longer period than in girls.
This prolonged exposure to IGF-1 is one reason why boys tend to grow taller despite starting later.
Growth Patterns: Fast vs Long
How Much Do Kids Grow?
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Girls: Peak growth rate is around 8–9 cm per year.
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Boys: Peak growth rate is similar or slightly higher—around 10–11 cm per year—but it persists for a longer duration.
That’s why boys usually end up taller overall—not because they grow faster, but because their growth phase lasts longer.
Think of it like a race: girls sprint early, boys run the distance.
Why Timing Is Key to Growth Support
Because of these differences:
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Girls have a shorter window between the start of puberty and the end of growth—often just 2–3 years from breast development to growth plate closure.
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Boys may have a longer growth period, but early signs can be subtle and easily missed.
| Gender | PHV Timing | Bone Maturity | Optimal Support Window | Missed Window Indicator |
|---|---|---|---|---|
| Girls | 1 year after breast development | Closure 1-1.5 years post-menarche | Age 9–11, Tanner stage 2 | Early menarche or bone age >13 |
| Boys | 1.5 years after testicular enlargement | Closure ~15–16 years old | Age 12–14, Tanner stage 3 | Voice change + bone age >14 |
Once the growth plates close, even excellent nutrition and sleep can no longer increase height. Identifying the growth window is more effective than trying to play catch-up afterward.
Key Takeaways
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Girls tend to start puberty earlier and grow faster—but stop sooner due to earlier estrogen-driven growth plate closure.
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Boys grow later and for longer, often ending up taller thanks to extended IGF-1 elevation and slower bone maturation.
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Hormones like estrogen, testosterone, GH, and IGF-1 all interact to shape height potential.
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The timing of growth support matters. Intervening during the right phase—especially before bone maturity—can make a meaningful difference.
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Knowing your child’s personal growth curve—not just their age—is key to helping them reach their full height potential.
Still have questions about your child’s height growth?
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