1. Memori
  2. ›
  3. Articles

Puberty Is Already Underway — Tanner Stages, Growth Spurts, and When to Seek Help

By Leon MoriguchiPublished May 15, 2026Updated May 18, 20266 min read日本語版あり
Audience
Parents of children in early-to-middle primary school (approximately ages 7–12)

TL;DR

  • ·The growth spurt arrives before the changes parents tend to notice: in girls, peak height velocity usually occurs between the start of breast development (Tanner B2) and B3, meaning that by the time menarche arrives, the most rapid phase of height gain has usually already passed
  • ·In Japan, the referral signs for precocious puberty include breast development before age 7 years 6 months in girls and testicular enlargement before age 9 in boys; for delayed puberty, the markers are testicular volume still below 4 mL at age 14 in boys and no breast development at age 13 in girls. Early evaluation of precocious puberty matters because premature growth plate closure can reduce final adult height
  • ·Regular height measurements logged twice a year produce a readable growth curve; a sharp upward step that emerged in the past is identifiable after the fact, and that record is useful clinical information at any specialist appointment

Contents

  1. Lead
  2. Background
  3. The Growth Spurt Comes Before You Expect It
  4. Precocious Puberty — Where to Set the Threshold
  5. Delayed Puberty and Constitutional Delay — When to Watch and When to Investigate
  6. Putting It Into Practice
  7. Summary
  8. References

Lead

One morning, while helping your child get dressed, you notice a body that looks subtly different from a few weeks ago. You find yourself wondering — when did that change? And then the questions: Is this too early? Or is this within the normal range?

This article introduces the Tanner staging system — the clinical framework used to assess pubertal development — explains how growth spurts relate to that framework, and outlines when to consider a medical evaluation for early or delayed puberty. The goal is to give you a reference point for making that judgment, not a prescription.

Partner Ultra / Ultra only

The rest of this article is for Partner Ultra / Ultra members

Anything affecting your child's health and safety is free. The more advanced reading is available to Memori members in the app.

Read the full article in the appSign in to keep reading →

Already a member? Sign in and the rest appears right here.

In the memori app

The memori app is built to follow your child against their own past, not against an average.

  • First roll, first word — milestones are kept with their dates.
  • Height, weight and head circumference are drawn over national reference curves.
  • You can find photos with a phrase like "at the beach last summer."
More about memori →
← PreviousMoving House and Young Children — What the Research Actually SaysNext →Bystanders Are the Majority — Reading Bullying Beyond the Bully-Victim Frame

Related

  • Traveling with a Baby — Cabin Pressure, Jet Lag, and Unfamiliar Beds
  • "Not Getting Up in the Morning" Is Not a Character Flaw — Understanding School Refusal and Orthostatic Dysregulation
  • Parenting Through Winter — Decision Criteria for RSV and Influenza Season