“It has long been known that girls reach puberty earlier than boys, that they become physically mature earlier. However, we wanted to investigate whether this also affects cognitive maturation. In other words, the ability to acquire knowledge,” says Marte Strøm.
Together with colleagues at the Institute for Social Research, Strøm has researched how gender differences in puberty and maturation can explain differences in school performance and the labour market.
The article “How important is girls’ ‘Biological Head Start’ in explaining gender differences in education and the labour market?” (2025) is written by Marianne Røed, Pål Schøne and Marte Strøm, all researchers at the Institute for Social Research.
Main findings: Early maturity has a clear impact on school results but is only a small part (8%) of the explanation for why girls get better grades.
Early puberty leads to better grades
Girls generally do better at school than boys.
Early puberty - better grades
Girls already have a head start when they start school, and they do better in school over all.
The Norwegian Official Report (NOU) “Nye sjanser – bedre læring” (“New chances – better learning”) from 2019 shows that girls have better language comprehension than boys even before they start school. Boys, on the other hand, have better spatial awareness than girls at the age of 4–6, which is an advantage in maths. But the differences are generally small. When they begin school, boys and girls are almost equally good at reading and maths.
However, differences increase, especially during the teenage years.
Puberty reaches its peak at the age of 15–16. Girls typically reach puberty 1–2 years earlier than boys. The earliest maturing girls can be four years ahead of the latest maturing boys, according to a Norwegian study.
What do these gender differences in maturity mean for performance at school – and for future opportunities in the labour market? This was the question Strøm and her colleagues asked.
“Is this the first study to investigate this?”
“Yes, at least using Norwegian data,” says Strøm.
“And what did you find out?”
“We found a clear correlation between pubertal development and school grades. Those who are further along in puberty perform better in school.”
The findings confirm research showing that early physical maturity leads to better school results. But the researchers have gone further. They wanted to find out how much of the differences in grades between boys and girls could be explained by differences in maturity.
The answer they found was surprisingly low: only 8 per cent.
In other words: Although puberty and physical maturity have some effect on school performance, this only accounts for a small part of the difference between boys’ and girls’ grades – the rest must be explained by other factors, such as differences in work habits, and differences in how boys and girls respond to teaching methods, the learning environment or evaluation methods.
“We expected puberty to play a greater role,” says Strøm.
Larger differences in UK study
A UK study from 2021 found that the impact of pubertal development on gender differences in school performance was roughly the same, but that it explained a larger proportion of the differences: almost 50 per cent. Martin Flatø is one of the researchers behind the UK study.
Flatø is a researcher at the Norwegian Institute of Public Health and participates in three projects on gender and maturation, including “Health Gap” and “Determined to Succeed”, which also includes Strøm’s project.
“Gender differences in school performance are greater in Norway than in England,” explains Flatø.
According to him, this may have influenced the findings in the studies.
“In Norway, performance in primary and lower secondary school is strongly influenced by language skills,” he says. “We know that girls have better skills in this area.”
“There has been a lot of talk about gender and school performance in Norway. Why hasn’t the topic of puberty been studied before?”
“The data hasn’t been good enough,” Flatø believes.
Data from the HUNT-study
Two types of data have been required: Data on pubertal development and data on school performance for the same individuals.
The study by Strøm and her colleagues is based on just such data sets, which they have linked together.
It used data from the Norwegian Ung-HUNT study, in which, since the end of the 1990s, young people from Nord-Trøndelag county have answered questions about bodily changes during puberty, such as growth, hair growth, breast development and first menstruation. The researchers used these answers to create one maturity scale.
“We see that girls who reached puberty early are more likely to complete their education and earn relatively more than those who mature later.”
To see how the participants performed at school and in the labour market, the researchers used other Norwegian register data from Statistics Norway (SSB).
The study is important, according to Flatø. But it also has a few weaknesses:
“Self-reported data can contain noise,” he explains.
This challenge was also present in the UK study: Participants may misremember or interpret questions differently.
Another factor that creates uncertainty about the findings is the indicator the researchers have chosen. Among other things, it combines data on height and early menstruation, which are two aspects of pubertal development. However, as research has shown, these aspects can pull school performance in opposite directions, says Flatø:
“For example, early menstruation in girls is associated with lower school performance and a higher incidence of ADHD. Height growth, on the other hand, has been shown to have a positive correlation with school performance, especially for boys.”
Flatø believes that the findings may therefore lead to an underestimation of the importance of age for pubertal development:
“The age of puberty onset probably has more to do with performance at school than the Norwegian study shows.”
According to Marte Strøm, the researchers have investigated different ways of calculating pubertal development, but the results do not change significantly depending on which method they use.
“For example, if we only include questions on height growth and hair growth, which can be measured for both genders, the difference in puberty explains about as much of the difference in school results as if we use all the questions,” she explains in an email.
Good grades can compensate poor pay
The Norwegian study examined not only school performance, but also how participants fared in the labour market.
“We see that girls who reached puberty early are more likely to complete their education and earn relatively more than those who mature later,” says Marte Strøm.
At the same time, however:
“On average, men in the labour market earn more than women. This means that while early maturity may give girls an advantage in school, it only helps to narrow the wage gap in a labour market that favours men.”
Flexible school start may help some
To even out the differences in school performance, experts have proposed various measures. The NOU from 2019 proposed, among other things:
- Limiting gender-segregated activities in kindergarten
- Introducing free preschool programmes for five-year-olds
- Strengthening special needs education in schools.
Flexible school start was also proposed, but the expert committee was divided on this. This means that parents can postpone the start of school for children who are considered too immature for first grade. Introducing a flexible school start scheme was also proposed by the Men’s Equality Commission in a report from 2024, to address boys’ challenges in school.
“Our findings may support the idea that flexible school start can help some children,” says Marte Strøm.
“But if the gender gap in school performance is 100 per cent, and maturity only explains 8 per cent of this, it shows that we can’t solve the entire challenge just by adjusting the school start age for boys.”
Look to Denmark
Martin Flatø is in favour of flexible school start and points out that Denmark has tested similar schemes.
“Denmark has greater flexibility throughout the education programme, and the gender differences are somewhat smaller.”
Experience from Denmark shows that more boys than girls have their school start postponed.
One benefit seems to be that fewer pupils born late in the year are diagnosed with ADHD.
In addition, the Danes have added an extra voluntary school year between lower and upper secondary school. This scheme has also been tested in some Norwegian municipalities.
“Such measures may be able to reduce the effect of puberty differences, especially in the long term,” says Flatø.
The article was first published in Norwegian, and updated on 6 March 2025 at 16.40. Translated by Totaltekst.
