Does a Girl Stop Growing Two Years After Her First Period?

In women’s health, I hear some version of this all the time: “She just got her period, so she has about two more years to grow.”

There is a little truth inside that statement. The problem is that it gets repeated like a rule, when puberty is much more variable than that.

A first period — menarche — usually means a girl is in the later part of pubertal growth. By then, the fastest part of her height spurt is generally behind her and growth is slowing. But menarche does not start a two-year countdown clock, and growth plates do not close on a menstrual anniversary.

What is actually happening around the first period?

Girls usually begin their major pubertal growth spurt after breast development starts. Peak height velocity — the point when height is increasing fastest — generally happens before menarche. Menarche commonly occurs about two to three years after breast development begins, when height velocity is already decelerating.

That is why the familiar rule sounds believable: most of the dramatic pubertal height gain has already happened by the first period. But “most of the growth is behind her” is not the same as “she will stop growing in exactly two years.”

How much height is usually left after menarche?

You will often hear that girls grow another 1 to 2 inches after their first period. That is a useful rule of thumb, but it is not a ceiling and it does not describe every girl.

A 2025 prospective study followed 534 healthy Chilean girls for up to four years after menarche. Average post-menarche height gain was 6.6 centimeters — about 2.6 inches — and the largest portion, about 3.8 centimeters, occurred during the first year.

An older U.S. study of 668 postmenarcheal girls from several racial and ethnic groups found something equally important for this discussion: 31% were still gaining at least 1 centimeter in stature two full years after menarche. Small amounts of skeletal growth could persist even longer.

So two years may describe the period when growth has slowed substantially for many girls. It does not define the exact point when growth stops.

Age at menarche changes the answer

This is one of the nuances that gets lost when we use a single rule for everyone.

In the 2025 cohort, girls who reached menarche before age 11 averaged more post-menarche growth than girls whose first period came after age 13. The earlier-menarche group gained about 8.2 centimeters over four years, compared with about 4.4 centimeters in the later-menarche group.

That does not mean an earlier period makes someone taller as an adult. It means the amount of growth that happens after menarche depends partly on where that girl was in her overall maturation process when menarche occurred. Final height is influenced by genetics, earlier childhood growth, pubertal timing, nutrition, health, and skeletal maturity — not by one milestone alone.

What about boys?

Boys are a useful comparison because they do not have one obvious milestone like a first period that families can use as a timestamp.

On average, boys enter their major growth spurt later than girls and reach peak height velocity later. Classic pediatric growth data place average peak height velocity around age 11.5 in girls and 13.5 in boys, although normal timing varies widely.

That is why a 13-year-old boy may still have a substantial amount of pubertal height growth ahead of him while a 13-year-old girl may already be well past her fastest growth phase. The calendar age alone still does not tell us exactly how much either child has left to grow.

The underlying biology is similar in an important way: estrogen helps mature and eventually close the growth plates in both girls and boys. In boys, some estrogen is produced when testosterone is converted to estrogen through aromatase. Growth-plate maturation is therefore a gradual hormonal and skeletal process in both sexes — not a switch tied to one birthday or one menstrual milestone.

What is more useful than counting two years?

If I actually want to understand how much growth an adolescent may have left, I care much more about the growth pattern than the calendar.

I want to know: How tall is the child now? How quickly has height changed over the last year or two? When did other pubertal changes begin? When did menarche occur, if applicable? What are the parents’ heights? Has the child stayed on a consistent growth percentile?

For most healthy adolescents, the growth chart and pubertal history tell us a lot. When there is a clinical reason to look more closely — unusually early or delayed puberty, an unexpected change in growth velocity, significant short-stature concerns, or a need to estimate skeletal maturity — a bone-age X-ray can add useful information. Even bone age is an estimate, not a crystal ball.

So is the two-year rule wrong?

I would call it an oversimplification rather than complete nonsense.

The useful part is this: once a girl has her first period, her fastest height growth is usually behind her, and the amount she grows each year will generally continue to decrease.

The part I would stop repeating as fact is: “She has exactly two years left.”

Some girls are essentially at adult height by then. Some are still gaining measurable height. Girls who reach menarche earlier may have more post-menarche growth remaining than girls who reach it later. And two girls who get their first periods on the same day can still have very different skeletal maturity and very different amounts of growth left.

A better sentence is: “Her first period tells us she is in the later part of pubertal growth, but how much height she has left depends on her individual growth and maturation pattern.”

It is not as catchy as the two-year rule. It is much closer to what the body actually does.

Sources

Gaete X, Ferrer-Rosende P, Pereira A, Mericq V. Post-Menarcheal Growth Patterns in a Contemporary Cohort of Latino Girls. Hormone Research in Paediatrics. 2025;98(1):66-74.

Cronk CE, Schall JI, Hediger ML, Scholl TO. Growth of postmenarcheal girls from three ethnic groups. American Journal of Human Biology. 1996;8(1):31-42.

Abbassi V. Growth and normal puberty. Pediatrics. 1998;102(2 Pt 3):507-511.

Grumbach MM. Estrogen, bone, growth and sex: a sea change in conventional wisdom. Journal of Pediatric Endocrinology & Metabolism. 2000.