The University of Auckland
GUiNZ_NWA12_Young peoples experiences of puberty at age 12.pdf (2.97 MB)

Now We Are 12: Young People’s Experiences of Puberty at Aged 12

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Puberty is a dynamic period of hormonal and physical development whereby a child’s body transitions to an adult body capable of reproduction. The age at which puberty occurs depends on complex interactions between factors such as sex, genetics, endocrine regulation, nutrition, and physical activity. Asking the Growing Up in New Zealand cohort about puberty allowed us to estimate puberty stages among 12-year-olds in Aotearoa, New Zealand and examine early and late development trends. We also captured young people's feelings about the processes their bodies are undergoing, providing insights that can inform a more inclusive Relationships and Sexuality Education (RSE) curriculum. Females were also asked about their access to free period products at school, giving insight into the success of Ikura/Manaakitia te whare tangata.

This report will examine young people’s experiences of puberty using data from the 12-year data collection wave of the Growing Up in New Zealand longitudinal study. We investigated the cohort's pubertal development at aged 12 to determine whether this differed by sex assigned at birth or self-reported ethnicity. We also explored how young people felt about the changes happening to their bodies, highlighting the diverse experiences of young people according to their sex and ethnicity. This report also describes the average age of first menstruation and use of free period products in schools among females who reported they had begun menstruating by aged 12.

Two main questions were addressed in this report.

  1. What proportion of 12-year-olds have begun puberty, and does this differ by sex or ethnicity?
  2. How are 12-year-olds feeling about the changes to their bodies with the onset of puberty, and does this differ by sex or ethnicity?

Finally, implications for policy and practice are discussed.


Crown funding managed by the Ministry of Social Development



Growing Up in New Zealand: University of Auckland

Spatial coverage

New Zealand

Temporal coverage: start


Temporal coverage: end


Data Collection Wave

DCW12 (12-year)