Between 1830 and 1960 there is a documented secular trend for a reduction in menarcheal age of about four months per decade declining from age 17 to around 12.8 years1. While recent literature argues that this decline has stabilised2, analyses of longitudinal data in Europe and America highlight a trend towards earlier female pubertal onset, and especially earlier breast development (thelarche) in girls3,4,5. Additionally, these studies find that girls in the highest weight categories are more likely to enter puberty asynchronously via thelarche, as opposed to the synchronous (simultaneous) development of breasts and pubic hair, or the asynchronous development via pubarche (pubic hair growth). So, it is suggested that an earlier pubertal onset is therefore lengthening the period between pubertal onset and menarche, and that heavier girls are most at risk of this phenomenon.

In the UK, a study using ALSPAC data5 found that heavier girls are more likely to enter puberty via thelarche. Further to these findings, this current study aims to understand long-term changes in puberty in girls in the UK, by using a number of longitudinal datasets. The goals are to understand: 1) whether age at pubertal onset has reduced from the period of 1960 to the present; 2) whether there is a continued secular trend for earlier age at menarche over the same period; 3) whether, there is a lengthening of the period from pubertal onset to menarche; 4) whether the heaviest girls enter puberty first, and 5) whether there is an increasing trend over that period for asynchronous pubertal development via thelarche, particularly for girls in the highest weight categories, and 6) whether UK trends are similar to girls in the USA and continental Europe.

ALSPAC is particularly useful in this context since the data contain extremely detailed pubertal and mid-childhood growth data on a number of children. Moreover, the data are relatively recent, and provide one of the most comprehensive, up-to-date databases for the analysis of current female pubertal development and its relationship with the changes seen in female puberty over the last 50 years.

Analyses of changes in female pubertal development will compare ALSPAC data with similar pubertal measures from the Harpenden growth study and the British Cohort Study. Additionally, trends in female pubertal development in the UK will be compared with hunter-gatherer and agriculturalist girls living in vastly different ecologies to the UK, where the impact of obesity and the modern environment is almost zero. This will indicate how the progression to different pubertal milestones (e.g. pubertal onset to menarche) differs across different ecologies.

1 Tanner, J.M. (1962) Growth at Adolescence. Oxford. Blackwell

2 Bau AM, Ernert A, Schenk L, Wiegand S, Martus P, Gruters A and Krude H. (2009) Is there a further acceleration in the age at onset of menarche? A cross-sectional study in 1840 school children focusing on age and bodyweight at the onset of menarche. Eur J Endocrinol. 160(1):107-13

3 Biro FM, Lucky AW, Simbartl LA, Barton BA, Daniels SR, Striegel-Moore R, Kronsberg SS and Morrison JA. (2003)Pubertal maturation in girls and the relationship to anthropometric changes: pathways through puberty. J Pediatr. 142(6):643-6

4 AU - Biro FM, Galvez MP, Greenspan LC, Succop PA, Vangeepuram N, Pinney SM, Teitelbaum S, Windham GC, Kushi LH and Wolff MS. (2010) Pubertal Assessment Method and Baseline Characteristics in a Mixed Longitudinal Study of Girls. Pediatrics. 126(3):E583-E590

5 Christensen KY, Maisonet M, Rubin C, Flanders WD, Drews-Botsch C, Dominguez C, McGeehin MA, Marcus M, (2010) Characterization of the correlation between ages at entry into breast and pubic hair development. Ann Epidemiol. 20 (5): 405-8.