Danish children are entering puberty significantly earlier than previous generations, raising concerns about inadequate sex education in schools. With girls menstruating around age 10 and boys experiencing changes months to years earlier than a decade ago, experts warn that delayed or inconsistent sexual education leaves young people vulnerable to misinformation from social media and pornography sites.
The Changing Timeline of Puberty
Puberty is arriving earlier than ever before in Denmark. Girls today are getting their first period approximately three months earlier than their mothers did, while boys are experiencing changes like voice deepening six months to one year sooner than Danish studies reported just 15 years ago.
This shift is not new. Since 1977, girls have been starting puberty an average of three months earlier with each passing decade. The historical change is even more dramatic. In the 1800s, Danish girls typically began menstruating at age 17. Today, that average has dropped to around age 13, with some girls experiencing breast development and other signs of puberty before age eight.
When Sex Education Falls Short
As puberty accelerates, Denmark’s approach to sex education has not kept pace. Sex & Samfund, a Danish sexual health organization, has launched its annual “Week Sex” campaign focusing on body changes and puberty signs for elementary school students. However, many teachers and experts argue that current instruction is inadequate and inconsistent.
Andreas Steffensen, an elementary school teacher, describes sex education in Danish schools as patchy and often left to individual teachers’ discretion. Because sex education is mandatory but receives no dedicated class time, and teacher training programs do not require coursework in the subject, instruction quality varies wildly from classroom to classroom.
Teachers Avoid Difficult Topics
Many educators find sex education challenging to deliver. According to Danmarks Lærerforening, Denmark’s teacher union, instructors frequently cite sexual education as one of the most difficult subjects to teach. Nearly one in five teachers have avoided teaching controversial topics, including sexuality and gender identity, according to a June 2025 study by VIVE, Denmark’s national research and analysis center.
The problem stems partly from teachers’ discomfort with the material. Without a common professional framework or required training, individual educators can simply decide the topic is too awkward and skip it entirely. This leaves students without consistent, age-appropriate information about their changing bodies.
The Consequences of Inadequate Education
When schools fail to provide timely, comprehensive sex education, young people turn elsewhere for information. Unfortunately, that elsewhere is often social media platforms and pornography websites, many of which children access before they legally should.
Majbrit Berlau, general secretary of Sex & Samfund, warns that insufficient or delayed sex education can leave young people feeling anxious or even frightened by the changes happening to their bodies. Without proper knowledge about what to expect, children entering puberty may become deeply insecure about normal physical developments.
Earlier Puberty Demands Earlier Education
The organization emphasizes that sex education works best when it arrives “five minutes early,” meaning just before young people actually need the information. However, in a classroom of 24 students who may be developing at different rates, timing that perfectly proves difficult.
Surveys conducted by Sex & Samfund show that most young people between ages 15 and 25 feel their school sex education did not adequately prepare them. This disconnect between what students receive and what they actually need suggests that Denmark’s current approach is failing an entire generation.
Understanding the Puberty Shift
Multiple factors contribute to Denmark’s declining puberty age. Anne Gaml-Sørensen, a lecturer at Aarhus University’s Institute of Public Health, explains that improved living conditions and better nutrition historically drove earlier menstruation between the late 1700s and 1840s. Girls cannot menstruate without sufficient body fat, which explains why better nutrition advanced puberty onset.
In the 1970s, Danish girls averaged 13 years old at first menstruation. Today, more girls are experiencing their first period around age 10. Boys are similarly affected, with earlier appearance of body hair and testicular growth.
Health Implications
Early puberty carries health risks beyond the immediate psychological challenges. Research indicates that children who enter puberty early face increased risks of obesity, diabetes, cardiovascular disease, and certain cancers later in life. They are also more likely to become overweight and develop insulin resistance compared to peers who mature later.
A comprehensive Danish study tracking 14,759 children through 73,160 questionnaires has documented this trend extensively. Researchers are now investigating whether causes originate during fetal development, examining whether exposures in the womb contribute to earlier puberty.
Calls for Educational Reform
Steffensen and other advocates believe Denmark must move beyond the current system where sex education depends on individual teacher comfort levels. They argue for standardized curriculum requirements, dedicated class time, and mandatory teacher training in sexual education.
Without these changes, Steffensen predicts that in five or ten years, Denmark will look back with regret at having failed to prioritize this education. The alternative to school-based instruction is allowing pornography sites and social media to shape young people’s understanding of sexuality and development.
Regitze Flannov, chair of Danmarks Lærerforening’s education committee, acknowledges that teachers want better skills and resources to deliver age-appropriate, high-quality sex education. Students find topics like sexuality and gender identity particularly sensitive, which makes the need for professional, well-trained instruction even more critical.
A Question of Equity
The current system creates what Steffensen describes as an “A team and B team” situation. Children with resourceful parents who discuss bodies, puberty, and sex at home arrive at school already informed. Meanwhile, children whose families do not have these conversations rely entirely on schools to provide that education.
Denmark’s public schools have a responsibility to support all students, particularly those without parental guidance on these topics. By establishing consistent, early, and comprehensive sex education, schools can ensure every child receives the information they need, regardless of their home environment.
Steffensen’s central concern remains stark. As children and teenagers encounter puberty earlier and access digital content younger, Denmark faces a choice about who will educate its youth about sexuality and development. Without decisive action, that role will default to platforms and content never designed with children’s wellbeing in mind.
Sources and References
The Danish Dream: The Best Education in Denmark: A Guide for Expats
The Danish Dream: Best High Schools in Denmark for Foreigners
TV2: Børn og unge går tidligere i pubertet – og overlades til pornosider, lyder bekymring
